Intelligent digital image storage for an electronic camera.

[Industrial Application] The present invention relates to electronic image processing, particularly image storage processing in an electronic still camera that stores an image captured in a removable digital image storage device.

PROBLEM TO BE SOLVED: To use a removable digital storage device widely used as a large-capacity storage device of a digital computer in the field of image storage processing at present. Such a storage device can store not only image data but also all kinds of electronic data such as database information, word processor documents, software programs, and the like. One of them is a PC memory card that complies with the PCMCIA PC Card Standard Release 2.0 (September 1991) issued by the Personal Computer Memory Card International Association (PCMCIA) in Sunnyvale, California. To use such a memory card in an electronic camera, the electronic camera processes and transforms the image data to comply with the card interface standard. Image data conforming to the standard is taken into the memory card via the interface on the hardware side that supports the card.

[0003] This type of writing concept is disclosed, for example, in US Pat. No. 5,801,017. According to this US patent, information on the image side such as exposure value and shutter speed and information on the camera body side such as an image processing system and compression mode are taken into one directory of a memory card. U.S. Patent Application No. 868163, filed by the Applicant on April 14, 1992, "Memory Card with Programmable" The advantage of the technology described in "Interleaving" is that the memory card has a control circuit that stores the interleaving factor input from the host system. Storage of interleaving factors identifies how data is distributed to multiple storage devices in a memory card. By varying the interleaving factors, the host system can associate data rates with specific uses. For example, when a personal computer is used as the host system, a low transfer rate can be tolerated, so that the interleaving factor can be reduced or eliminated. However, when the host system becomes a high-resolution camera, the interleaving factor will increase because the transfer is performed in real time. U.S. Pat. No. 4887161 provides examples specific to other images. In this US patent, the memory card has a display. The stored image is read by the processor of the memory card and displayed on the display. This processor can erase unnecessary images in response to a cancellation request input from the camera body.

[0004] [Problems to be Solved by the Invention] As described above, in the trend of adopting PCMCIA-compliant memory cards, despite proposals to give digital storage devices image-specific capabilities. However, the situation in which the electronic camera side transforms the image data into a form suitable for storage and processes it has not changed. Since an image is represented by a large amount of binary data, which often reaches a data amount of several megabytes, the data must be compressed by the electronic camera body for storage. For example, processing of color space and fine images is also a part of such processing. As a result, even if data is stored in a digital storage device, it can only be read by a camera or processor of the type that originally transformed / processed the data. There is a long-awaited storage technology that realizes a digital storage device as a general-purpose device that can support various types of cameras and processors while taking advantage of the current technological advantages.

[Means and Actions for Solving the Problems] The digital storage device provided by the present invention has image-specific data processing capabilities such as color space and compression, and handles and processes image data in the storage device itself. Will be possible. Seen from the outside, this digital storage device operates like a "black box" regardless of the data format. The image is taken by the camera and then stored in the storage device. At that time, the camera side is released from the burden of arithmetic processing required for processing and storing image data. Therefore, the storage device is responsible for reading the image data from the storage device and displaying the original image on the image reader. Depending on the storage device, the image may be processed into another form and displayed on the image reader.

[0006] According to the present invention, a digital storage device is detachably connected to an electronic camera, and the electronic camera generates an image signal and outputs the image signal from an output unit. The digital storage device includes an algorithm memory for storing a plurality of algorithms for processing an image signal, and a signal interface for transmitting a signal between the output unit of the electronic camera. When a write command signal is input from the electronic camera via the signal interface, the processor selects one of the algorithms stored in the algorithm memory and feeds it through the interface according to the selected algorithm. Process the image signal. The processed image signal is stored in the image memory section.<u style="single">.. The digital storage device has a characteristic memory for storing the information of the supported function provided by a plurality of algorithms, and the information of the characteristic memory is supplied to the electronic camera via the signal interface and selected from the information of the characteristic memory. , The algorithm stored in the algorithm memory is selected according to the write signal command supplied from the electronic camera via the signal interface.</u>[Examples] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Since electronic cameras and digital storage devices that use CCD sensors are well known, only elements that are directly related to the device according to the present invention or that are a part of the device will be described. Those skilled in the art are free to select elements that are not specifically mentioned. Further, the drawings are merely one specific example of the present invention, and other types of interfaces and the like are also interpreted as being within the scope of the present invention. In the following description, an example in which the present invention is applied to a still camera is shown, but the present invention can also be used as a storage medium for digital moving images by an electronic moving image camera.

[0008] FIG. 1 shows an electronic still camera 12 to which the intelligent storage device according to the present invention is applied. As the storage device, for example, various devices such as an EEPROM memory, a flash memory, a static RAM memory, a dynamic RAM memory, a magnetic memory (floppy or hard disk), and an optical memory are used. In the illustrated example, a memory card 10 using a solid-state integrated circuit memory is used as an intelligent storage device. A storage card of the same shape, including a hard magnetic drive, may be used. The memory card 10 includes a plurality of non-volatile EEPROM memory devices 14a, 14b, 14c for storing image data input from the input interface 16 to the card 10. In the illustrated example, only three EEPROM memory devices are shown, but more than that are usually used. Further, in addition to the parallel interface shown in the figure, a serial interface, an optical interface, or the like can be used. The memory card 10 includes an interface address, a buffer 18 that latches a control signal input from the interface 16, a programmable processor 20, and a non-volatile algorithm memory 22. The data bus 23 connects these elements. The characteristics of this memory card are stored in the characteristic table 21 as described later. The input interface 16 includes a card-side connector 24, which is shaped to be connected to the camera-side connector 26 of the electronic camera 12.

[0009] The electronic still camera 12 includes an exposure unit 30 that directs light from a subject (not shown) toward the image sensor 32. The optical system 34 of the exposure unit 30 allows light from the image to pass through the diaphragm 36. The diaphragm 36 adjusts the optical aperture. The shutter 38 of the exposure unit 30 adjusts the exposure time. The sensor 32, which includes a photosites matrix corresponding to the pixels of the image, is a well-known charge-coupled device (CCD) using a well-known interline transfer or frame transfer technique. The sensor 32 is covered with a color filter array 40. The sensor 32 is exposed to image light and analog image charge information is generated for each photosite. The charge information supplied to the output unit 42 is converted into an analog image signal corresponding to each pixel. The analog image signal is supplied to the A / D converter 44, and a digital image signal is formed from the analog input signal for each pixel.

[0010] The digital signal is sent to the image buffer 46. The image buffer 46 is composed of a random access memory (RAM) having a storage capacity of at least one image. The stored signal is sent to the digital signal processor 48, and the digital signal processor 48 performs signal correction such as white balance and gamma correction. The corrected digital signal is sent to the output interface 49. The control processor 50 initializes and controls the exposure. To control the exposure, the diaphragm 36 and the shutter 38 are operated, a horizontal clock or a vertical clock is formed to drive the sensor 32, and the image data from the sensor is clocked. The control processor 50 receives an instruction from the user input unit 52. The instructions include a shooting command, selection of a compression algorithm to be used, and the like. As will be described later, the instruction may include the selection of an algorithm such as a color space. The control processor 50 detects the exposure state from the photocell 54 and displays the operating conditions on the display device 56. Various functions provided by the card 10 are displayed on the display device 56, and a desired function is selected by operating the user input unit 52. Depending on the exposure conditions, the processor 50 operates the flash unit 58. The operation code of the camera 12 is stored in the ROM memory 60.

[0011] When the control processor 50 is activated, the shooting sequence is initialized in response to a shooting command from the user input unit 52. The diaphragm 36 sets the aperture and the optimum exposure time for the shutter 38 is selected. This selection follows information such as ambient light data obtained through the photocell 54 and the use of the flash unit 58. The resulting image is read from the image sensor 32, converted into a digital signal by the A / D converter 44, and processed by the digital signal processor 48 for storage in the memory card 10. The control processor 50 sets the appropriate control signal to the output interface 49. According to the present invention, a determined control signal indicates a process to be performed by the memory card 10. For example, a separate control signal is supplied to interface 49 depending on whether the user input 52 selects compression without any loss or visually lossless compression. In addition, there are control signals that instruct writing, reading, and erasing. The control signal identifies that the data is appearing on the data line, but the specific addressing is done by the processor 20 of the memory card 10.

[0012] The image card 10 has two basic functions. It is a write function and a read function. Here, the writing function refers to a command for changing the state of the card 10, and the reading function refers to a function that does not change the physical state. FIGS. 2 to 4 show these functions in the form of a flowchart. According to the "image writing" function, an image having a specific resolution can be stored in the image card 10. In this embodiment, there are two types of "image writing" functions. "Image writing without loss" and "Image writing without loss at the visual level". In addition to these "image writing" functions, the writing functions include managed functions. Managed functions include "image card erasure" and "selective image erasure" that are appropriate depending on the capabilities of the image card. In addition to the "image read" function, the read function includes a management type function. This management type function includes "image card characteristic reading", "image count reading", and the like. The reading function can be performed not only from the camera 12 but also from a reading device such as a player, a printer, or a display device. There is no limit to the number of card functions, including managed functions. For example, in this embodiment, the following functions are included.

[0013] A. Writing function (1) An image stored according to the "lossless image writing" function will be reconstructed without any data loss. There is no loss, either as a whole or mathematically. The code for the lossless algorithm is stored in the algorithm memory 22. Lossless coding includes run-length coding. This run-length coding is a data compression method that encodes a series of the same characters as a single numerical value. In certain areas where image processing is applied, such as in the medical field, images are extremely sensitive to compression and deformation. In such a case, the camera 12 needs to store the image in a form without any loss. Even in this case, the camera 12 only supplies a control signal to the output interface 49 according to the input from the user input unit 52. This control signal indicates that the memory card 10 should use a lossless compression algorithm. Upon receiving the control signal, the processor 20 restores the lossless algorithm from the algorithm memory 22, compresses the input digital signal according to this algorithm, and stores the compressed signal in EEPROM 14a, 14b, 14c.

(2) The image stored according to the "image writing without loss at the visual level" function is reconstructed so that there is no loss at the visual level. That is, it is reconstructed with a visually acceptable loss. As visual lossless coding, there is a compression technique using discrete cosine transform or differential pulse code modulation. This function may be selected by a command from the camera 12 or may be selected by the image card. Which one you choose depends on the available storage space of the image card. When letting the image card choose, the image card may choose to store the image according to "lossless image writing" if storage capacity allows. This storage method also allows the image to be reconstructed without loss at the visual level. Similar to lossless image writing, when the appropriate control signal is input to the card, the processor 20 restores the visually lossless compression algorithm from the algorithm memory 22 and processes the input digital image signal according to this compression algorithm. .. Some types of image compression used for any of the functions are based on a "black box" -like approach technique in this way, and are not harmful to the outside.

(3) The "image card erase" function is used to initialize an image card without having any image data. The code for the erase function is stored in the algorithm memory 22 and is accessed according to the erase command from the camera.

(4) The "selective image erasure" function is used to selectively erase one image from an image card to reserve space for another image to be stored later. .. The code for this function is stored in algorithm memory 22.

B. Reading Function (1) According to the "image reading" function, the specified image contained in the image card 10 is transferred from the image card 10 to the camera 12. The transfer destination may be another reading device (not shown), for example, a display or a printer. No matter what kind of image data is reconstructed, the image card side is responsible for reconstructing any image data when transferring the image data to the camera using the color space of the image. In particular, the "image read" signal causes the processor 20 to derive an appropriate decompression algorithm from the algorithm memory 22. Subsequently, decompression processing is performed in the card 10, and the decompressed data is read from the card 10 to the camera 12 through the interfaces 16 and 19. Since it is not read from the image card in the form of compressed image data, this card is inherently versatile for a wide range of imaging and processing devices.

(2) The "image card characteristic reading" function is used to determine the ability of the image card with respect to the image storage functionality and the image processing functionality of the image card to be used. Card characteristics are included in the characteristic table 21 and are accessed according to instructions from interface 16. The information obtained by this function includes the following. A list of supported features such as color space, output rendering, compression and other types. Data transfer rate. "Image characteristics" bytes. In one use of this feature, the list of assisted features is read from table 21 by the control processor 50 and displayed on display 56 of camera 12. Therefore, the user of the camera (or reading device) selects an appropriate function, and the card 10 processes the image data according to the selected function.

(3) In the "image count reading" function, the camera 12 (or reading device) determines the number of images stored in the image card 10 . The code for this function is stored in algorithm memory 22.

[0020] These card functions are shown by the flowcharts shown in FIGS. 2 to 4. In each case, the command bytes are transmitted from interface 16 and read by processor 20. The command byte takes various forms, but it is shown as follows in the flowchart.

A. When "write" is announced Image write without loss 00h Image write without loss at the visual level 01h Image card erase 02h Selective image erase 03h B. When "read" is announced Image read 00h Card Characteristic read 01h Image count read 02h Given the appropriate combination of statements and directives, the selected function will be performed. For example, both the lossless image writing function and the visual level lossless image writing function acquire image characteristic bytes from the camera side, and the camera obtains the image data format stored in the image card, that is, the color used. It is possible to specify the space, the number of bytes per pixel, and the like. The image characteristic bytes are stored in the card. The X and Y dimensions of the image are then acquired, which determine the required storage space. Image data is transferred and stored. At that time, it is stored as lossless data or lossless data at the visual level depending on which algorithm is required. The write-based erase function works as shown in Figure 3. Particular attention is paid to selective image erasure. In this selective image erasure, the erasure is restricted by the image number obtained from the camera, and the erasure is followed by the remaining images. The read function is the opposite of the write function. First, a desired image number is obtained from the camera (or reading device), and then the image characteristic byte and the XY direction dimension are supplied to the camera (or reading device). Finally, the image data is restored by appropriate decompression processing or other processing and transferred to the camera (or reading device).

The image card 10 and its interface 16 are specifically designed to store only image-related data. Image data formats that can be provided for image cards include 24-bit RGB (red, green, blue) in the existing color space. This image data format covers not only the density or difference of color data but also different color spaces and can be adapted to various applications. In this format, the image card interface 16 allows the storage and reproduction of 24-bit RGB image data of a certain image size, i.e., a certain X / Y dimension. The color space of the image data in the image card interface is specified by the "card characteristics" table 21, and may differ depending on the type and model number of the image card for each application. In other words, which color space is supported by the card is determined by the "card characteristics" table 21. Color spaces include, for example, the "Photo YCC" color space (published by Eastman Kodak in Rochester, New York and used in its Photo CD system) and the commonly known CCIR709, CIELab or There is a standard color space such as CIELuv. The image card assumes that the image data is provided in the selected / specified color space, and unless otherwise instructed, the image will be reconstructed in this color space during image playback. .. If instructed, the card 10 restores the color space algorithm selected from the algorithm memory 22 and converts the image data into a new color space accordingly.

[0023] The algorithm memory 22 of the card 10 may include an algorithm that sends out the stored image data, that is, an algorithm that processes the image data prior to a specific output path or usage format. For example, the image data stored on the card is sent to an output printing device that operates in a specific color space. In this case, an additional writing function such as a "memory of specific output" function is provided. The control signal that obtains such an effect is issued by the control processor 50, an appropriate sending algorithm is restored from the algorithm memory 22, and the formed image output is transformed into a format suitable for the output device.

[0024] The processing of the image data on the card is performed by the processor 20 using the energy from the camera. In essence, such processing is easy for the camera and its users to understand. Black box image data processing such as compression, color space conversion, and color delivery may be performed immediately after reception by the card 10 or may be delayed. How long you can delay depends on the card conditions and the required processing format. For example, the processing may be performed immediately after the image is captured and stored, or the processing may be delayed until the camera escapes from the "standby" mode waiting for the imaging command. You may further delay the process and wait for the card 10 to be disconnected and disconnected. In the latter case, the card itself will have a power supply to drive the internal processor 20 and other elements.

[0025] According to this image card, image storage can be performed according to the resolution. When writing an image to an image card, the X / Y direction dimensions of the image are given. When reading an image from an image card, the image card supplies the host with X / Y dimensions of the image prior to transferring the image data. In addition, when reading an image, the image can be read from the card 10 as a subsampled or scaled. For example, it includes a "cropped read" instruction that causes the processor 20 to restore a special subsampling algorithm from the algorithm memory 22 and subsample the stored image data accordingly.

[0026] When a 24-bit RGB format image capturing format is assigned, pixels of image data are formed in that order with red (8-bit), green (8-bit), and blue (8-bit) data. This 3-byte sequence is called an RGB triplet. A typical write / read sequence is as follows. When writing image data to an image card, the host camera forms RGB triplet data that starts at the top left corner of the image and moves from left to right and from top to bottom. Also, when reading image data from the image card to the host camera, the image card forms RGB triplet data that starts at the top left corner of the image and moves from left to right and from top to bottom. The data bus 23 of the image card 10 is, for example, an 8-bit parallel bus with an additional control line that enables high-speed data transfer. Its maximum data transfer rate can vary depending on the version / model of the image card.

[0027] Although the present invention has been described in detail with reference to preferred embodiments as described above, changes and modifications can be made within the scope of the idea of the present invention. For example, the technique used to couple the image card to the camera 12 may be a metal pin / socket coupling, as can be seen in FIG. 1, or may be substantially optical. Yet another may be a high speed serial interface. The format of the interface is not necessarily limited to these, and other formats may be adopted. Further, regarding the algorithm memory 22, an example having a certain number of stored algorithms has been described, but in order to modify an existing algorithm or add a new function, from an appropriate host processor via a write protection function. You may update it.

[Effects of the Invention] As described above, the present invention has mainly the following advantages over a general computer storage medium. First, the photographing apparatus does not need to perform the usual logical processing for storing the image data in the physical medium. Second, the photographing apparatus does not need to perform actual image processing such as compression required when storing image data. With such a "black box" approach, the readout device does not have to process and reproduce the image data from the physical medium, and moreover, the image data can be stored even if it is compressed during storage. No need to stretch. In addition, this "black box" approach establishes image quality consistency in memory and subsequent reproduction for display and printing. Therefore, uniform image processing is performed in the storage device itself. Since the camera must accompany the standard of the interface of the image storage device in any case, according to the concept of the image storage device of the present invention, it contributes to the standardization of electronic image storage for the electronic photographing device. Image storage devices with different capabilities then work with cameras that fit into a common interface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an electronic image processing system including an electronic camera and a digital storage device according to the present invention.

FIG. 2 is a flowchart showing a writing function supported by the digital storage device of FIG.

3 is a flowchart showing a writing function supported by the digital storage device of FIG. 1. FIG.

4 is a flowchart showing a read function supported by the digital storage device of FIG. 1. FIG.

[Code description] 10 memory cards, 12 electronic still cameras, 14a, 14b, 14c memory devices, 16 interfaces, 18 buffers, 20 programmable processors, 21 characteristic tables, 22 algorithm memory, 23 data buses, 24 card edge connectors. , 26 Camera Edge Connector, 30 Exposure, 32 Image Sensor, 34 Optical System, 36 Diaphragm, 38 Shutter, 40 Color Filter Array, 42 Output, 44 A / D Converter, 46 Image Buffer, 48 Digital Signal Processor, 49 Output interface, 50 control processor, 52 user input, 54 photocells, 56 display, 58 flash unit, 60 ROM memory.