Method and device for processing a digitized image stored in a first computer, computer-readable storage medium

0001METHOD AND DEVICE FOR EDITING A DIGITIZED IMAGE SUBJECT TO A FIRST COMPUTER, AND COMPUTER READABLE STORAGE MEDIUM

0002The invention relates to a method and a device for processing a digitized image with pixels stored in a first computer, a computer-readable storage medium and a computer program element.

0003Today, a plurality of computers are interconnected via a communication network, such as the Internet / Intranet. The information transmitted from one computer to another computer via the Internet usually contains both text-based data and graphic data, that is to say image data or multimedia-processed Internet applications, for example video data and / or audio data.

0004One application of data transmission of multimedia data is electronic catalogs provided by a server computer whose operator is, for example, a department store for retrieval by a client computer via the Internet / Intranet.

0005The performance of the individual computers, which are coupled with each other via the communication network, is steadily increasing. It can be assumed that the speed of a processor in a computer doubles every year, but the cost of such a processor remains constant. A corresponding development of the continuous considerable increase in performance is also observed in the hardware for digital image processing.

0006Furthermore, the available bandwidth via a communication network is steadily increasing. In this context, the communication network is understood to be any type of communication network via which information can be transmitted, for example a landline telephone network, a mobile radio network. The transmission of the data can be based on any communication protocol, on the Internet for example on the Transport Control Protocol (TCP) and the Internet Protocol (IP).

0007As a result of the steadily growing bandwidth available, the information provided on the Internet must meet ever-higher quality standards, which means that its multimedia quality must be continually improved in order to remain competitive.

0008To encode digitized images, be they still images or even video images, that is to say a chronological sequence of images, coding standards have developed with which it is possible to provide color information associated with the pixels of a particular digitized image in real time.

0009Color depth (24-bit color depth) to be transmitted via the Internet.

0010An example of such a coding standard is the GIF format, which allows for a very high level of compression of the coding information, that is the information associated with the pixels of the digitized image, which characterizes the image.

0011Coding information in this context is to be understood, for example, as one of the following types of information:

0012• color information, and / or

0013• brightness information, and / or

0014• Saturation information about the saturation of the respective color, and / or

0015• Contrast information. By means of the GIF format, however, only 256 colors can be displayed, exactly 236 colors, since 20 colors are used for the representation of window frames, backgrounds etc.

0016Another coding standard for encoding still images, that is, for encoding a still image, is the JPEG format.

0017The coding according to the JPEG standard is lossy.

0018The degree of quality loss can be specified in the encoding of a digitized image, for example to determine, depending on the content of the image, the degree between the quality of the coded image information and the file size of a file in which the digitized image is coded.

0019The JPEG graphics format supports 24-bit color depth, which means that this encoding standard enables true-color representation of image information.

0020Another example of a coding standard for coding a still picture is the coding standard according to the PNG format.

0021According to the PNG standard, both the color depth and the quality, that is the degree of information loss during compression, can vary.

0022In addition, according to the PNG standard, a transparency mask can also be saved in order, for example, to be able to display graphics objects freely. Cropping a graphics object means that the graphics object can be individually selected, separated from the rest of the image, and embedded in one or more other graphics objects, such as a new image background. For example, in the case of a product photograph as a graphic object, cropping means that the product photograph can be separated so that the photo-background can be separated from the product and thus the product photograph can be embedded in any other graphic environment.

0023In the context of electronic commerce, not only electronic catalogs are transmitted via the Internet, but nowadays cashless payment transactions are also being made. The very fast response times and the very convenient way to trade, cause more and more suppliers of products, such as department stores, to offer and distribute their products over the Internet.

0024An electronic catalog is thus often supplemented or replaced by a so-called electronic department store, by being able to order and pay for the articles viewed in the electronic catalog, for example, directly online via the communications network. The purchased products are then delivered directly to the buyer of the product.

0025In the area of ​​true-color representation of image information, it is thus possible for a user, that is to say a viewer of a data display unit, to display image information in more colors than the eye of this viewer can perceive.

0026In particular, in an electronic department store, in which the corresponding products can be viewed via the electrical catalog, but recorded very many

0027Product suppliers have high return rates, ie a high rate of purchased products that have to be taken back by the respective electronic department store. Often, upon return of the purchased product, the purchaser of the product complains that the purchased products have been displayed in the electronic catalog in a different color representation on the data display unit attached to his computer compared to the actual post-delivery product Colour .

0028The deviation in the color representation of the electronically displayed object and the real object, in particular the deviation of the color representation on different monitors of different computers compared to the real object color is thus a major cause of the user's dissatisfaction and the high response rate.

0029In [1] a method for color correction is known in which it is determined on the basis of given for a data display unit standard ICC profiles, whether a respective data display unit is set up to display colors. Color correction is optionally performed using the standard ICC profiles stored in the data display unit.

0030This approach is disadvantageous because only a limited and also predetermined number of standard ICC profiles are provided and thus only an inaccurate and in particular to specific conditions such as changing light conditions color representation is possible.

0031[2] describes the so-called cookie mechanism.

0032In [3] it is described that color matching can be performed in the HLS color space.

0033Another system for color correction is described in [4], again using predetermined color profiles according to this system.

0034The invention is thus based on the problem of processing digitized images stored in a first computer with pixels, so that a substantially uniform color representation of the image on a respective data display unit is made possible with computers interconnected via a communications network.

0035The problem is solved by the method and apparatus for processing a digitized image stored in a first computer with pixels associated with first encoding information by a computer readable storage medium and a computer program element having the features of the independent claims.

0036An apparatus for editing a digitized image stored in a first computer

0037Pixels to which first coding information is assigned have a processor that is set up in such a way that the method steps described below can be carried out and performed during operation.

0038For processing a digitized image stored in a first computer with pixels associated with first encoding information, data display unit parameters of a data display unit connected to a second computer are set by a user of the data display unit and subsequently supplied from the second computer via a telecommunication network transferred to the first computer. The Datenanzeigeeinheits- parameters describe the data display unit, in particular their display properties, that is their properties in terms of the representation of digitized image information.

0039The first encoding information associated with the digitized image is changed to second encoding information depending on the data display unit parameters, and the digitized image thus modified is transmitted to the second computer where it can subsequently be displayed on the data display unit to a user of the second computer.

0040The first encoding information and the second encoding information may include at least one of the following types of information:

0041• color information, and / or • brightness information, and / or

0042• Saturation information about the saturation of the respective color, and / or

0043• Contrast information.

0044In a computer-readable storage medium is a

0045Computer program for editing a stored in a first computer digitized image with pixels to which the first coding information is assigned, stored, wherein the computer program comprises the method steps described above, if it is from a

0046Processor is running.

0047A computer program element for processing a digitized image stored in a first computer with pixels associated with first encoding information comprises the method steps described above when executed by a processor.

0048Illustratively, the invention can be seen in that determined data display unit parameters, the respective

0049Describes data display unit of a client computer, are transmitted from the respective client computer, that is to the first computer, serverseit ig an adjustment of the image information to be transmitted to the peculiarities of the respective data display unit of the client computer is changed and the thus changed image information is transmitted to the respective client computer, so that an adapted to the respective data display unit of the respective client computer and optimized image representation, in particular color representation and brightness display and contrast display is possible.

0050In this way, thus an automated, very simple and accurate and individual adaptation of provided digital image information is also possible in a very heterogeneous communication network with very different data display units.

0051This leads, in particular in the field of electronic commerce, that is to say in the scenario described above, to a considerably reduced response rate of purchased products.

0052In particular, due to the possibility for the user to set the different parameters of their own display unit automatically in a simple manner, for example by means of sliders, is a simple, flexible adaptation of the properties of the display unit on the specific and frequently changing environmental conditions on the user side, for example, on changing lighting conditions, possible.

0053Preferred developments of the invention will become apparent from the dependent claims.

0054The further embodiments of the invention relate to the method, the device, the computer-readable storage medium as well as the computer program element.

0055The first color information associated with the first coding information and / or in the second one

0056Encoding information contained second color information may be present in an RGB color space representation, hereinafter referred to as RGB color mode (red, green, blue).

0057The invention can be implemented both in hardware, that is to say by means of a special electronic circuit and in software, that is to say by means of a computer program.

0058According to a development of the invention, it is provided that the first coding information has first color information and the second coding information has second color information. The first color information is changed to the second color information, wherein the change of the color information is performed in an HLS color model representation, hereinafter referred to as HLS color mode (H: color angle in color wheel, L: brightness of color, S: saturation of color ).

0059Changing the color information in the HLS color mode allows a very accurate, to the respective

0060Characteristics of a data display unit adaptable change of the image information to be displayed, that is, both the color information, as well as the brightness information and the saturation information.

0061At the beginning of the process, the data display unit parameters of the data display unit can be determined or set, that is, the data display unit parameters can be manually or automatically determined and stored.

0062At the beginning of the process, a communication link to the first computer may be established by the second computer, and after the communication link has been established, the data display unit parameters may be automatically requested from the first computer. Due to the request, the data display unit parameters may be transmitted from the second computer to the first computer via the communication network.

0063This can be automated, for example, if the Internet / Intranet is used as the communications network and a browser program for every second computer,

0064TM for example the Internet Explorer or the Netscape

0065TM Navigator for the respective browser program accessible a cookie file to be stored, which immediately after the establishment of the communication connection to. the respective first computer, that is transmitted to the server computer, whereby the data display unit parameters of the respective client computer are provided to the server computer.

0066A cookie is a server-side mechanism (usually initiated by CGI scripts), which stores information on a WWW client computer and can be queried again by the WWW server computer. For certain Internet applications (search engines, e-business, etc.), the personal preferences of the client computer can be stored locally, so that the user next time you call the domain (URL) does not have to re-set. The actual cookie consists of the relevant information in the respective cookie file, which is similar to a passport, stamped each time you enter a territory.

0067Under a cookie file in this context is thus illustratively a file to understand, which in the second

0068Computer is stored and can be retrieved by the respective browser program by a corresponding query message from the server computer and which specifiable information, according to the embodiment of the invention, the data display unit parameters of

0069Data display unit of each connected to the second computer data display unit contains, and thus is transmitted to the server computer.

0070This provides a very simple mechanism for transmitting and remotely calibrating a data display unit over the Internet.

0071According to another embodiment of the invention, it is provided that a plurality of different data display unit parameters are determined and stored for a data display unit, wherein each set of data display unit parameters, ie each set of data display unit parameters, is assigned description information describing the respective sets of Describe data display unit parameters.

0072The description information may include at least one of the following types of information:

0073Environmental parameters describing environmental conditions for which the data display unit parameters of the respective set of data display unit parameters are determined, and / or

0074Time information describing a period of time for which the data display unit parameters of the respective set of data display unit parameters are determined.

0075This embodiment of the invention makes it possible to respond to different environmental conditions or for different periods of a day, for example, for a period of time in which daylight in the particular room in which the computer and the data display unit connected to the computer usually stands and operates or in a period of time when only artificial light, that is, artificially generated light, is provided, and to consider it. In this way, a flexible adaptation of the image representation to different operating conditions is made possible, which leads to a further improvement in the color fastness of an image displayed on a data display unit of a client computer.

0076A set of data display unit parameters may be selected depending on the description information, and the selected data display unit parameters may be transmitted to the first computer.

0077An embodiment of the invention is illustrated in the figures and will be explained in more detail below.

0078Show it

0079Figure 1 is a flowchart in which the individual

0080Process steps of the method according to an embodiment of the invention are shown;

0081Figure 2 is a block diagram showing a communication system according to an embodiment of the invention;

00823 shows a representation of an input mask for the

0083Color correction of a data display unit as part of a system level calibration;

0084FIG. 4 shows a representation of an input mask for the brightness correction of a data display unit in FIG

0085Framework of system-level calibration;

0086FIG. 5 shows a representation of an input mask for the

0087Color correction of a data display unit as part of an application-level calibration; FIG. 6 shows a representation of an input mask for the

0088Brightness information of a data display unit as part of an application-level calibration;

0089FIG. 7 is an illustration of a color wheel according to the HLS color model;

0090FIG. 8 a representation of a color circle according to the HLS color model with additional indication of brightness information;

0091FIG. 9 shows a flowchart in which the individual method steps for changing the coding information according to an exemplary embodiment of the invention are illustrated;

0092FIG. 10 is a diagram showing a color correction in the RGB color mode.

0093First embodiment:

00942 shows a communication system 200 with a server computer 201 as the first computer and a plurality of client computers 202, 203, 204, each as a second computer, each via a public communication network 205, according to this embodiment, a telecommunications fixed network, which can transmit data using the Internet Protocol is coupled.

0095Alternatively, the public communication network 205 may also be designed as a complete or partial mobile radio network.

0096The server computer 201 and the client computers 202, 203, 204 are each coupled to the public communications network 205 via links 206, 207, 208, 209. In principle, any number of client computers 202, 203, 204 and any number of server computers 201 may be included in the communication system 200.

0097It should be noted in this context that the term server computer or client computer is merely functional to understand, based on one application. In other words, a client computer that consumes a first service with respect to which it acts as a client can be configured as a server in another application, that is, in another service, that is, as the entity, which provides the respective service.

0098It should also be noted that in an alternative embodiment of the invention, any number of server computers may be provided in the heterogeneous communication system 200, which may be based on different operating systems and different application programs.

0099It is only important that bi-directional communication between the server computer or the server computers 201 and the client computers 202, 203, 204 is possible over the public communications network 205.

0100The server computer 201 and the client computers 202, 203, 203

0101204 each comprise the following components: a network input / output interface 210, 211, 212, 213, via which in each case a communication via the Internet, that is, the public communication network 205 is enabled,

0102A processor 214, 215, 216, 217, a memory 218, 219, 220, 221,

0103• another input / output interface 222, 223, 224, 225 • wherein the network input / output interface 210, 211, 212, 213 of the processor, 214, 215, 216, 217, the memory 218, 219, 220, 221 and the further input / output interface 222, 223, 224, 225 are each coupled to one another via a computer bus 226, 227, 228, 229.

0104In each memory 218, 219, 220, 221 is in each case a browser program, according to this embodiment, an Internet Explorer ™ or a Netscape Navigator program ™ is stored, which are executed by the respective processor 214, 215, 216, 217 can.

0105Furthermore, stored in the memory 218 of the server computer 201 is an electronic catalog 230 containing a plurality of multimedia information, that is to say in particular

0106• text-based information, that is textual data,

0107Graphic information, ie digitized images,

0108• video information, ie digitized video data, • audio information, that is to say audio data.

0109The Internet browser programs stored in the memories 219, 220, 221 of the client computers 202, 203, 204 are arranged to enable a

0110Save cookie file, which can be queried by a server computer 201.

0111At each computer 201, 202, 203, 204 is via the respective further input / output interface 222, 223, 224, 225 via a respective first cable as a first connection 230, 231, 232, 233, a data display unit 234, 235, 236, 237 connected.

0112As data display unit 234, 235, 236, 237 can be provided in each case, for example

0113A screen with a cathode ray tube, a liquid crystal screen,

0114• a (laser) projection display unit.

0115A computer mouse 242, 243, 244, 245 is connected via a respective second cable as a second connection 238, 239, 240, 241 and a keyboard 250, 251, via a respective third cable as a third connection 246, 247, 248, 249. 252, 253.

0116It should be noted in this context that the individual compounds each also as, for example

0117Infrared connection or as a radio link,

0118TM preferably using the so-called Bluetooth

0119Technology can be realized.

0120The respective data display units 234, 235, 236, 237 can thus have very different properties, in particular with regard to their properties in the representation of color information, for example with regard to the different representation of the primary colors red, green and blue, as well as the representation of brightness information or saturation information of the respective colors or the contrast information.

0121Each data display unit 234, 235, 236, 237 is calibrated at the beginning of the process.

0122The calibration can be done at the system level or, alternatively, at the application level, as further explained below.

0123It is further assumed that the respective data display unit 234, 235, 236, 237 is a conventional monitor of a personal computer, which has a cathode ray tube and control electronics for converting the respectively supplied signal into the drive of the deflection unit of the cathode ray tube as a picture tube. The representation of the signal on the screen of the monitor can be influenced by varying the signal parameters red, green and blue as well as brightness and contrast, which are entered in particular by means of a rotary control, alternatively by means of push buttons or online, that is by means of an on-screen menu on the monitor can.

0124In order to enable the most color-correct reproduction of a digitized image and its coding information on a monitor, it makes sense to calibrate the monitor, that is to say the data display unit 234, 235, 236, 237, before it is used. The data display unit 234, 235, 236, 237 should be turned on at least 30 minutes before the start of the calibration to allow the individual

0125Components of the data display unit 234, 235, 236, 237 have reached their respective operating temperature. Only after this time has passed should the calibration be carried out.

0126In a typical graphics card (not shown) in the respective computer 201, 202, 203, 204, the respective color component of red, green and blue as well as the brightness and the contrast can also be set at the system level.

0127A system level calibration of the data display unit 234, 235, 236, 237 is performed using the graphics card and monitor combination as described below.

0128By means of the respective graphics card driver and the associated configuration software, color areas of the three primary colors red, green and blue are displayed, whose respective inner fields consist of a variable color area. The color of the inner fields can be changed by moving sliders. Fig. 3 shows a screen entry mask 300 over which a user inputs a

0129Calibration of its data display unit 234, 235, 236, 237 at system level can perform. In the input mask 300, three color areas 301, 302, 303, one color area each for a base color (first color area 301 for the base color red, second color area 302 for the base color green, third color area 303 for the base color blue) are shown.

0130Each color surface 301, 302, 303 respectively has an inner color field 304, 305, 306 and an outer color field 307 which completely surrounds the respective inner color field 304, 305, 306,

0131308, 309 on. By clicking on each of a slider 310, 311, 312, wherein a respective slider 310, 311, 312 a color area 301, 302, 303 is assigned, the color of a respective inner color field 304, 305, 306 can be varied.

0132The aim of changing the color in the respective inner color field 304, 305, 306 is, in the context of the calibration, to match the color in the inner color field 304, 305, 306 as closely as possible to the color of the outer color field 307, 308, 309. A more detailed explanation of the operation will be given later.

0133The color value set for the respective base color within the scope of the calibration is recorded and evaluated by means of the graphics card driver and the associated configuration software.

0134Another step in system-level calibration is the brightness adjustment of each

0135Monitor, that is, the data display unit 234, 235, 236, 237.

0136A brightness input mask 400 customary for this purpose is shown in FIG. The input mask 400, also called

0137Comparative mask, has a first field 401, which is usually black, and a second field 402, which is usually dark gray on.

0138A brightness control of the monitor (not shown) is changed until the dark gray areas 402 for the user are clearly distinguishable from the black areas 401.

0139The values ​​set in this way for the brightness values, which in each case for the respective

0140Data display unit are individually adapted to be used to correct the screen display and influence within the respective graphics card, the implementation of the digital color value for a pixel in which for the connected monitor, that is for the connected data display unit 234, 235, 236, 237 matching digital signal.

0141The ratio of the three color values, (RGB) to each other, indicates the direction of the color cast of the respective data display unit 234, 235, 236, 237.

0142For an optimally set monitor, the ratio of the colors of the values ​​for the color red, green and blue is 1: 1: 1.

0143Since in this way the color shift is known, that is the shift of the respective values ​​of the colors red, green and blue, it is now possible by means of the graphics card to take into account the color cast of the respective data display unit 234, 235, 236, 237 and in the illustration of an image to convert the color components accordingly.

0144If the adjustments, ie the calibration is performed, a correct color reproduction is guaranteed within the entire user environment. A simplified calibration option provides calibration at the application level.

0145An application-level calibration means that the calibration of the respective data display unit 234, 235, 236, 237 has only an effect on those digitized images displayed within the respective application.

0146It is assumed that the respective

0147Data display unit 234, 235, 236, 237 have been set substantially color correct by the respective users.

0148For example, a landscape image will typically include a blue sky and a green field.

0149The data display units 234, 235, 236, 237 will usually differ significantly relative to each other in their respective display characteristics.

0150The input screens 300, 400 shown in FIGS. 3 and 4 are, according to this exemplary embodiment, displayed on an Internet page to a user who accesses the Internet page, that is to say, and is correspondingly processed, that is adapted, by a respective user ,

0151The values ​​for the description of the characteristics of the respective data display unit 235, 236, 237 determined in the adaptation by the user are stored in a cookie file in the respective Internet browser program which is stored in the memory 219, 220, 221 of the respective client computer

0152202, 203, 204 is stored.

0153Usually, the respective client computers 202,

0154203, 204 during the constantly varying composition of communication links, that is, during the "surfing" on the Internet different, dynamic IP addresses, whereby an identification of the respective client computer 202, 203, 204 may not be possible at a later date, with which a storage of color settings on a central Internet server is often not possible.

0155The information about the respective individual color setting of the respective data display unit 234, 235, 236, 237 and the graphics card on the respective client computer 202, 203, 204 is thus clearly stored in the cookie file, without interventions in the respective system, that is, the hardware itself, are necessary. The cookie file and the data display unit parameters stored therein can thus be retrieved at any time from a server computer.

0156In the following, the respective procedure for calibrating the data display unit 235, 236, 237 will be explained in greater detail using FIGS. 5a to 5c and 6.

0157The respective tiled area 501, 502, 503 of the respective color field 504, 505, 506 is invariable in its colors.

0158In a very fine grid, pixel by pixel (pixel by pixel) is alternately the respective base color, that is, the respective pure color, displayed with maximum intensity (value for first base color red: 255, value for second base color green: 255, value for third base color blue: 255) as well as a black field. This results in alternately arranged in each case a first field 507, 508, 509 in the respective base color and a respective black field 510, 511, 512th

0159A lower area 513, 514, 515 is variable by means of a respective slider (not shown). If the checkerboard pattern is viewed through fields 507, 508, 509 and 510, 511, 512, respectively, by means of a human eye, the black and colored areas 507, 508, 509 and 510, 511, 512, respectively, blur and yield as shown in FIG Observers visual visual perception of the respective base color with an intensity of 50%, in other words expressed as a value for the first base color red of 127, with a value for the second base color green of 127, and with a value for the third base color blue from 127.

0160The respective lower color field 513, 514, 515 is displayed with the intensity of an intensity value of 127 and changed by means of the respective slide control until the two color fields appear to be the same for the viewer.

0161Subsequently, the value of the respective color (red, blue or green) represented by the position of the slider is determined.

0162For an optimally set data display unit 234, 235, 236, 237, the respective values ​​are at a value of 127.

0163An upward deviation, that is, color values ​​greater than 127, means that a higher intensity of the respective color is necessary to see a visual perception of 50% of the respective color.

0164A deviation downwards, ie a value smaller than 127, means that a lower intensity of the respective base color is necessary, in order to ensure a visual perception of the respective color of 50%.

0165In the input mask 600 shown in FIG. 6, the black field 601 is immutable in terms of its brightness, but the color areas 602 shown in gray can also be changed by means of a slide control (not shown).

0166The gray areas 602 are to be changed by the respective user until no difference between the respective black field 601 and the gray color areas 602 is visually detectable for him.

0167The gray value thus obtained indicates the information as to when a brightness level of one color is distinguishable from the next, and thus how bright the respective data display unit 234, 235, 236, 237 is set.

0168If, in the manner described above, the respective

0169If the primary colors red, green and blue have been adjusted and the brightness has been determined, these values ​​are stored in the respective cookie file for later calculation of the "remote calibration" procedure of the data display unit 234, 235, 236, 237 explained in detail below.

0170In the memory 218 of the server computer 201, a computer program is also installed, which first each digitized image before being transmitted to a client computer 202, 203, 204 with the in the cookie file of the respective client computer 202, 203, 204 corrected color values ​​corrected.

0171An internet page, such as the electronic catalog 220 stored in the memory 218 of the server computer 201, in which images contained in the electronic catalog are to be displayed correctly, shall be programmed so that all in the respective internet page contained images (hereinafter also referred to as image tags) a published Internet page by calling the installed conversion program with the respective transfer of the file name of the image to be displayed are replaced.

0172The following is an example of a common HTML code fragment used to display an image:

0173<img src = "pics / picture jpg">

0174The image tags are to be encoded as follows by calling the computer program explained in more detail below:

0175<img src = "scripts / correction. dll? name = pics / image jpg">

0176where by means of the indication "Korrektur.dll" the name of the respective correction program is specified and in the

0177Directories "scripts" and "pics" each server-computer-individual names of directories may be included.

0178FIG. 1 shows in a flow diagram 100 the method steps to be performed when a call is made by the client computer 202, 203, 204 via the respective browser program to the Internet page provided by the server computer 201, symbolized in FIG through a first block 101.

0179In a first step after selecting the

0180The Internet side of the server computer 201 checks whether a corresponding calibration of the data display unit 235, 236, 237 has already been carried out for the data display unit 235, 236, 237 of the respectively selecting client computer 202, 203, 204, that is to say whether a cookie File is stored in the respective memory 219, 220, 221 in which the data display unit parameters of the respective data display unit 235, 236, 237 are stored (step 102). If this is not the case, a color correction is performed for the respective data display unit 235, 236, 237 in one of the ways described above (step 103).

0181The determined data display unit parameters are stored in the cookie file in the memory 219, 220, 221 of the corresponding client computer 202, 203, 204.

0182Subsequently, a further method step is passed on (step 105), in which branching takes place immediately if the checking step 102 reveals that a cookie file was already stored in the memory 219, 220, 221.

0183In this method step (step 105), the respective Internet page provided by the server computer 201 is loaded by the respective client computer 202, 203, 204.

0184In an iterative process, the individual HTML tags of the HTML code by which the Internet page is encoded are processed (step 106).

0185In a next step, it is checked whether the respectively edited current HTML tag is an image tag (test step 107).

0186If this is not the case, ie if the HTML tag is, for example, a text-based tag or also a video tag or an audio tag, the HTML tag is processed immediately (step 108) and the user of the respective client computer 202 , 203, 204 (step 109).

0187However, if the HTML tag is an image tag, the respective cookie file stored in the client computer 202, 203, 204 becomes the server computer from the respective client computer 202, 203, 204 via the public communications network 205 201 transferred (step 110). Thus, the individual stored color values, generally the data display unit parameters, are transmitted from the respective client computer 202, 203, 204 to the server computer 201 and are thus available in the server computer.

0188In a further step, the color values, as explained in more detail below, of the image tag to be transmitted on the server side, that is, by the server computer 201, corrected (step 111).

0189The corrected, that is the processed digitized image is transferred from the server computer 201 in a further step (step 112) to the respective client computer 202, 203, 204 and in the subsequent display step (step 109) to the user of the client computer. Computers 202, 203, 204 are displayed.

0190In a further step, it is checked whether the subsequent HTML tag is a "new page" HTML tag (step 113).

0191If this is not the case, a branch is made into method step 106, in which the next HTML tag of the current Internet page is processed.

0192However, if the HTML tag "new page", in other words, the current Internet page is completely processed, then the process step 105 is branched, in which a new Internet page can be loaded.

0193In the following, the color model of the primary colors red, green, blue (RGB color model) is explained in more detail in order to simplify the illustration of the invention.

0194In RGB color mode 11, a color dot is represented by its red, green, and blue components, represented in a 24-bit color mode by 8 bits each of the corresponding base color.

0195This results in a theoretical color number of 16,777,216 colors.

0196On the other hand, according to the HLS color model, a color is described by the respective color angle in the color wheel 700 (see Fig. 7), the brightness of the respective color, and the saturation of the respective color.

0197The information according to the HLS color model is not used for display, but is for internal calculation and can be adapted as desired.

0198This means that if a color of a color of the proportion of saturation of a particular priority, so the degree of accuracy in favor of the saturation value can be adjusted.

0199In particular, a correction of a color cast having a data display unit 234, 235, 236, 237 can be realized in the HLS color mode 11 in a very simple manner.

0200In this context, a key aspect is the appropriate color angle.

0201The color angle determines the respective color on the color wheel 700.

0202The unit of measure is angular degrees, with an angle of 0 degrees corresponding to the color red, an angular value of 60 degrees to yellow, an angular value of 120 degrees to green, an angular value of 180 degrees to cyan, an angular value of 240 degrees to color Blue and an angle of 300 degrees of the color magenta. The primary colors red, green and blue form an equilateral triangle in the color circle 800 (see FIG. 8), the complementary colors yellow, magenta and cyan form an equilateral triangle rotated by 60 degrees, the respective complementary colors red cyan, green magenta and Blue-yellow are on the respective color circle 800 opposite.

0203A color cast in a color is to be compensated, ie corrected, by the corresponding opposite color, that is to say by means of the corresponding complementary color.

0204Thus, if a gray color field has a reddish color, the reddish color is corrected by means of the color cyan in order to be able to reproduce the color gray.

0205The HLS color model shown in the color circle 800 in FIG. 8 additionally contains the information about the brightness of a color.

0206The brightness information starts in the center 801 at 0%, which corresponds to a brightness "black" and ends at a brightness information of 100%, which corresponds to a brightness "white", on the outer edge 802 of the color wheel 800.

0207Analogously to the explanation described according to FIG. 5, the color cast is corrected via the color angle and the brightness is adjusted by means of a change of the distance of the respective color point in the color circle 800 to the center 801.

0208A digitized image, which is present in accordance with the RGB color mode, is first converted into the HLS color model, that is to say transformed, for the purpose of calculation, that is to say for the corresponding color compensation. By decomposing the coding information into the color component, the saturation and the brightness, there is a targeted manipulation of the coding information.

0209The colors to be displayed on the data display unit 235, 236, 237 are adapted on the one hand in their color angle, that is, the corresponding color cast is removed, on the other hand, the brightness of the data display unit 235, 236, 237 is compensated by manipulating the color brightness.

0210According to this embodiment, a color value is present as a number triplet RGB in the RGB color mode 11, wherein in the number triplet RGB the color values ​​R, G and B lie in an integer range from 0 to 255 and represent the respective proportion of the corresponding base color.

0211In a first step, the number range of the number triplet is normalized according to the following rules:

0212rr = -, (1)

0213255

0214G g = (2) 255

0215Bb = (3) 255

0216Then the highest and lowest color content is determined according to the following rules:

0217cMax = maximum (r, g, b), (4)

0218cMin = minimum (r, g, b). (5)

0219The brightness 1 is then calculated according to the following rule: _ (cMax + c in)

0220(6)

0221wherein the brightness value 1 is in a range between 0 and 1.

0222To calculate the saturation value s, a case distinction is to be made.

0223If gil:

0224cMax = cMin, (7)

0225all normalized values ​​of the number triplet r, g and b are the same, and then the color is a gray value and thus has no saturation, with the result that the color angle can not be determined.

0226In other words, this means that

0227cMax = cMin, (7)

0228s = 0, (8)

0229h not definable. (9)

0230Otherwise there is a coloration of the respective pixel. The saturation value s is to be determined as a function of the brightness value 1 according to the following rule:

0231cMax <> cMin, (10)

02321 &lt;0.5, (11)

0233<img file="WO02065754A1_D0001.tif" />

02341> 0.5 (13) <img file="WO02065754A1_D0002.tif" />

0235where the saturation value s is in the range between 0 and 1.

0236The value for a color angle h is determined according to the following rules and depends on the maximum of the individual components of the normalized RGB color values:

0237r = max (15)

0238h = k-^b>. , (16)

0239(cMax - cMin)

0240g = max (17)

0241_H = ₂ + ₇ ^ - I ₍₁₈)

0242(cMax - cMin)

0243b = max (19)

0244<img file="WO02065754A1_D0003.tif" />

0245In a further step, the color angle value h is converted to an angular degree according to the following rule:

0246h = h • 60 (21)

0247h &lt;0 (22)

0248h = h + 360. (23) The value ranges of the individual values ​​ascertained above, that is to say the value ranges of the color angle value h, the brightness value 1 and the saturation value s are determined according to the following rules:

02490 &lt;h &lt;360 degrees, (24)

02500 ≤ 1 ≤ 1 brightness, multiplied by the value 100 results in the percentage value, (25)

02510 &lt;s &lt;1 saturation value, multiplied by the value 100 results in the percentage value. (26)

0252The procedure described above is based on articles

0253Q29210 from the Microsoft Knowledge Base.

0254The digitized image now converted to the HLS color mode is corrected according to the data display unit parameters of the respective client computer 202, 203, 204.

0255In a subsequent step, that is, when the digitized image has been processed in the HLS color mode, it is displayed on the respective one

0256Data display unit 235, 236, 237 of the corresponding client computer 202, 203, 204 converted back into the RGB color mode.

0257This is done according to the following procedure:

0258The color values ​​H, L and S are available and are first normalized according to the following rule:

0259h = - ^ -, (27)

0260360 (28)

0261100

0262S = -. (29)

0263100

0264If the saturation value s has the value 0, then there is no color, but a gray value, which depends on the brightness value 1. All color values ​​R, G and B are the same. The color values ​​R, G and B are in an integer range from 0 to 255, that is 8 bits per color are used for encoding.

0265In other words, in the case that the saturation value s has the value 0, this means that the color values ​​R, G, B result according to the following rules:

0266s = 0, (30)

0267R = [l • 255], (31)

0268G = [l • 255], (32)

0269B = [l • 255]. (33)

0270If there is color, ie if the saturation value s is not equal to 0, it must be distinguished whether the color contains more black (1 <0.5) or more white (1> 0.5).

0271Two auxiliary variables v1 (first auxiliary variable), and v2 (second auxiliary variable) and an auxiliary procedure h2RGB, which is also explained below, are used for the calculation.

0272In the case that applies:

0273s <> 0 and 1 <0.5 (34) results in the second auxiliary variable v2 according to the following rule:

0274v2 = 1 • (l + s), (35)

0275and in the event that more white is present, that is, if:

0276s <> 0 and 1> 0.5 (36)

0277this results in the second auxiliary variable v2 according to the following rule:

0278v2 = 1 + s - (l • s) (37)

0279The first auxiliary variable vl results according to the following rule:

0280vl = 2 • 1 v2 (38)

0281and the individual color values ​​RGB result according to the following regulations:

0282R = h2RGB v1, v2, h + flY. 255 (39) AJJ

0283G = [h2RGB (vl, v2, h) • 255], (40)

0284B = h2RGB v1, v2, h - 255: i; v3y

0285The auxiliary procedure h2RGB graphically represents the conversion of a value from a quadrant of the color wheel 800 into Cartesian coordinates. The auxiliary procedure h2RGB is called by means of the following call:

0286erg = h2RGß (vl, v2, h). (42)

0287The following calculation steps are carried out as part of the auxiliary procedure h2RGB:

0288If the color angle value h &lt;0, the angle value h is increased by the value 1, that is to say:

0289h &lt;0 (43)

0290h = h + 1. (44)

0291If the color angle value h> 1, the color angle value h is lowered by the value 1, that is to say:

0292h> 1 (45)

0293h = h - 1. (46)

0294If the brightness value after changing the color angle value h is greater than six times the color angle value h, that is to say:

02951> 6 • h, (47)

0296The auxiliary procedure is again called with the following parameter values, that is, according to the following call:

0297h2RGB = (vl + (v2 - vl) • h • S). (48)

0298If the brightness value 1 is greater than twice the color angle value h, that is to say in the case where

02991> 2 • h, (49) the result is the following rule:

0300h2RGB = v2. (50)

0301Is the triple color angle value h &lt;2 (ie:

03022> 3 • h, (51)

0303the result value is as follows:

0304A₂ h2RGB = vl + (v2 - vl) h (52)

03053)

0306For all other cases, the result value is assigned the value of the first auxiliary variable vl, that is to say:

0307h2RGB = vl. (53)

0308FIG. 9 in a flow chart 900 summarizes the individual method steps described above in detail.

0309In a first step (step 901), the respective client computer 202, 203, 204 uses the server computer 201 to load the data display unit parameters, that is to say the respective cookie file.

0310In a further step (step 902), the respective image file is loaded from the memory 218 of the server computer 201 and decoded in the memory 218 of the server computer 201 (step 903).

0311In a further step, the following steps are carried out for each color point, that is to say for each pixel to which the color values ​​for the three primary colors are assigned (symbolized by a loop block 904): The respective color values, ie the RGB values, are read out ( Step 905) and the RGB values ​​are converted to the HLS color model (step 906).

0312In the HLS color mode, the colors are corrected

0313(Step 907) depending on the correction values ​​in the cookie file, that is, depending on the data display unit parameters.

0314In a further step, the corrected color values ​​in the HLS color model are converted back into the RGB color model according to the rules described above (step 908).

0315In a further step, the last step of the

0316Analysis loop 904, the respective corrected RGB value is written back to the memory 218 of the server computer 201 (step 909).

0317If all the pixels of the image to be corrected have been corrected by the server computer 201 in the manner described above, then the processed, that is the corrected digitized image is transmitted to the corresponding client computer 202, 203, 204 (step 910).

0318In an alternative embodiment of the invention it is provided that in the respective client computer 202, 203, 204 a plurality of different service display unit parameter sets are stored, each containing data display unit parameters for different environmental conditions or for different times, including different environmental conditions to rule.

0319If the Internet page is called up for such a case, for example, a time associated with the respective set of data display unit parameters is compared with a current time, and the set of data display unit parameters matching the current time is selected.

0320Depending on the respective time indication conclusions can be drawn on the time of day, that is, for example, on the presence of daylight or on the fact that in any case artificial light as an environmental condition ^■ is to be assumed, and accordingly, an optimized on the environmental conditions amount of

0321Data display unit parameters for correcting the image information from the respective client computer 202, 203, 204 selected and transmitted to the server computer 201 for correcting the image to be transmitted.

0322In the above-described first embodiment of the invention, the color correction is performed in the HLS color space, in other words, the color information is changed in the HLS color mode.

0323In the further exemplary embodiments set forth below, the color information is changed in the RGB color mode, the YMC color mode or also in the YMCK color mode.

0324In the first embodiment, the HLS color mode was used. This procedure offers the maximum achievable accuracy in the context of changing the color information. A change in the color information, as described in the other embodiments, while not exact, but provides sufficient quality for the visual representation of true color images. In this context, it is assumed that the digitized images stored in the first computer are stored in color-correct or neutral color.

0325The procedure of the first embodiment with regard to the data flow between the first computer and the second computer, and the data flow for calculating the color correction remain in the other

0326Embodiments unchanged. Also, the described adjustment tools for calibrating the screens remain unchanged, wherein in the other embodiments can be dispensed with a setting of the brightness, since the brightness of a color is determined by an equal overhead to all individual color components.

0327Second Embodiment (Change of Color Information in RGB Color Mode):

0328In the RGB color mode, all colors and brightnesses are represented by combining the red, green and blue portions of a color, with the values ​​of the individual color components between a lowest color component value "0" and a highest color component value "255". For each color component, one byte is provided in each case, with which any color can be represented by means of three bytes.

0329In other words, according to the second embodiment, the RGB color mode 11 is used for color correction.

0330The RGB color model can be clearly understood as a Cartesian coordinate system in which the primary colors red, green, blue are plotted on the mutually orthogonal coordinate axes. The coordinate axes are finite, ie, in the coordinate system origin, the value of a respective base color is "0" at the endpoints of the coordinate axes "255".

0331The RGB color mode11 sets all colors in the range • 0 &lt;red &lt;255,

0332• 0 &lt;green &lt;255,

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0380According to the correction means determined with the adjustment tools described in the first embodiment, it is known how far the graphics subsystem the user computer is away from the optimal neutral setting. Each value of the number triplet of a pixel is charged according to the second embodiment with the set values ​​for red, green and blue. If the numerical value resulting from the adjustment tools is greater than 127, the difference is subtracted from the corresponding color component. If the numerical value resulting from the adjustment tools is less than 127 or 127, the difference is added to the corresponding color component.

0381After the respective number triples have been calculated correspondingly for all pixels, the image corrected in this way is transmitted to the second computer, giving the user a color-accurate image.

0382The second exemplary embodiment describes the method by way of example for a color range around the value of 127 in each case, that is to say at approximately 50% color intensity. This can no longer be used at the respective end values ​​0 and 255, otherwise numerical values ​​smaller than 0 or greater than 255 can result.

038310 shows a diagram 1000 in which the procedure for the calculation set out above is illustrated by way of example for a color.

0384The beginning in the coordinate system origin 1001 line 1002 with the function

0385f (x) = x (54)

0386represents the ideal color distribution. By means of the

0387Farbeinsteilwerkzeugs the value z is determined. Diagram 1000 is used to derive the functions with which the color points of the image are calculated.

0388For values ​​less than 127:

0389f (x) = - • x. (55)

0390127

0391For values ​​greater than 127, the following applies:

0392f (x) = (255 - z) • x. (56)

0393For each color value of the primary colors of the image to be displayed, the corrections according to the above-mentioned function 1003 are calculated and subtracted from the original color value or added to the original color value.

0394Exactly, no straight lines result for the color correction, but one approximates a circle equation. Since, however, it is assumed that the original images or the basic setting of the graphics subsystem is largely color correct, the deviation from the straight line will only occur within a small frame.

0395For this reason, it is also possible in this case to work with linear functions, which considerably accelerates the feasibility of color correction.

0396Third Embodiment (Change of Color Information in YMC Color Mode):

0397In the YMC color mode, all colors and brightnesses are represented by the colors yellow, magenta and cyan, which are complementary to the colors red, green and blue.

0398In other words, according to the third embodiment, the YMC color mode 11 is used for color correction. The YMC color mode 11 follows from the RGB color model 1 by rotating the colors on the color circle 700 in Fig. 7 by 60 °.

0399The procedure for color correction in the YMC color mode according to the third embodiment corresponds in principle to the procedure for color correction in the RGB color mode according to the second embodiment.

0400Fourth Embodiment (Change of Color Information in YMCK Color Mode):

0401In the YMCK color mode, a black component is also stored as an additional component compared to the YMC color mode. The YMCK color mode is commonly used in professional printing applications. The YMCK color mode can be returned to the YMC color mode at any time.

0402The procedure for color correction in the YMCK color mode according to the fourth embodiment corresponds in principle to the procedure for color correction in the RGB color mode according to the second embodiment.

0403This document cites the following publications:

0404[1] WO 00/23944

0405[6] US 6,035,339

0406[3] Patent Abstracts of Japan JP 01016658 A

0407[4] Patent Abstracts of Japan JP 10276294 A