Screen aspect-ratio conversion apparatus for television has adaptive output unit to determine valid detection letter box border values

BACKGROUND OF THE INVENTION

1. Field of the invention

The present general inventive concept relates to a screen-to-height ratio conversion device and method, and more particularly to a device and method for preventing frequent conversion of a width-to-height ratio that occurs due to frequent changes of detected letterbox boundaries when letterbox boundaries are automatically detected. and for adaptively converting an aspect ratio.

2. Description of the prior art

Generally, a television set as one of the image display devices allows users to select a vertical aspect ratio of an input image by varying pixel aspect ratios in the vertical direction in various ways regardless of the aspect ratio of the input image to accommodate programs on the view a screen that has a selected vertical aspect ratio. However, most conventional television sets have a screen width to height ratio of 4: 3 in an image format of the screen of a cathode ray tube (CRT) type image display device. Similarly, most image (signal) sources have the 4: 3 screen width to height ratio. That is, not all image sources have the 4: 3 screen-to-height ratio. For example, movies (movie image signal or movie source) are converted from a movie format to a video tape format in order to be reproduced or transmitted as a television signal. Such movie sources need to be converted to have the 4: 3 screen width to height ratio suitable for most television sets when converted to the video format. The film sources include widescreen (wide screen) image sources which have an image format of, for example, a 16: 9 screen width to height ratio.

Devices such as a flying spot telecine are used to convert the film sources into video tape format. The flying spot telecine has a window or frame with a 4: 3 screen-to-height ratio, and in general an operator of the flying spot telecine moves the window left and right, with the left and right sides of the movie images as much as possible cut off while following the action in the movie, since the width of the movie images is wider than the width of the screen with a 4: 3 aspect ratio when the height of the movie images fits within the screen of the 4: 3 aspect ratio. Thus, if a film source with a 16: 9 screen width to height ratio is converted into an image signal with the 4: 3 aspect ratio, part of the image signal is not displayed because the image is cut off from the movie images.

If widescreen images with a 16: 9 aspect ratio are scaled to an image width that fits within the left and right boundaries of a screen with a 4: 3 aspect ratio, the height of the widescreen images should be scaled further. As a result, the widescreen images are completely displayed on the screen of a 4: 3 aspect ratio, but a part corresponding to the top and bottom of the screen of the 4: 3 aspect ratio cannot be displayed. Therefore, dark edges are displayed at the top and bottom of the widescreen images displayed on the screen of a 4: 3 aspect ratio in order to avoid a spurious signal that can be generated in the portion not shown.

Such dark-edged images are commonly referred to as letterbox-sized images. That is, the letterbox format images have blank spaces at the top and bottom of an area on which the images are displayed and the blank spaces (letterbox areas) correspond to non-signal areas. If there are letterbox areas in an input image, the image is not displayed in the letterbox areas, but is displayed in a substantial image area outside the letterbox areas.

In a conventional auto-wide function implemented in an image device, an image size in the substantial image area other than the letterbox areas is switched to another image size suitable for the screen of the image image device. The auto-wide image size switching function detects the input image width-to-height ratio based on the letterbox boundaries separating the letterbox areas from the substantial image area.

Conventionally, letterbox areas are detected by comparing successive lines of the input image. However, a conventional method of detecting the letterbox boundaries often switches image sizes that exist during imaging when computer graphics interface (CGI) such as subtitles and logos exist in the letterbox areas and the conventional method cannot accurately detect the boundary values ​​of the letterbox areas due to detect the edges at the substantial boundaries of the letterbox areas containing subtitles or logos. Frequent changes in the image size and aspect ratio of the imaged images thus create a problem that television viewers may experience visual fatigue.

SUMMARY OF THE INVENTION

The present general inventive concept provides an aspect ratio conversion device and method that have an auto-wide function to provide viewers with greater convenience and stability by using active and inactive areas and by determining only the letterbox limit values ​​associated with the valid detection values. active areas.

Additional aspects and advantages of the present general inventive concept will be partly set forth in the following description and partly clear from the description or may be learned from practice of applying the general inventive concept.

The foregoing and / or other aspects of the present general inventive concept can be accomplished by providing a aspect ratio conversion device comprising a letterbox boundary detecting unit to detect letterbox boundaries of a current input image, an adaptive output unit to determine whether the detected letterbox boundary values ​​are valid and to output the detected letterbox boundary values ​​if the detected letterbox boundary values ​​are valid, and a scaling unit to adjust the size of the substantial image area to fit the size of a screen of a display device based on the letterbox boundary values ​​received from the adaptive output unit.

The letterbox limit values ​​can include a letterbox upper limit value and a letterbox lower limit value.

The adaptive output unit may include a threshold value setting unit to set the threshold values ​​dr_a, dr_b, drl, dr2, dr3 and dr4 corresponding to the size of the current input image, an inactive area setting unit to set a first inactive area and a second inactive area in a first active area and a second active area, respectively located above the previous letterbox upper limit value and below a previous letterbox lower limit value, based on the letterbox upper limit and letterbox lower limit values ​​detected from a previous image and the threshold values ​​dr_a and dr_b provided from the threshold setting unit, and a comparing unit to determine whether the letterbox upper limit value of the current image belongs to the first active area and whether the letterbox lower limit value detected from the current image belongs to the second active area and to determine whether the letterbox limit values ​​detected from the current input image are valid.

Widths of the first and second inactive regions can be determined by the threshold values ​​dr_a and dr_b.

The inactive setting unit can control an image center portion of the current input image to which a substantial signal is input to overlap the first and second inactive areas.

The width of the first active region can be determined by the first and second threshold values ​​dr1 and dr2 and the width of the second active region can be determined by the third and fourth threshold values ​​dr3 and dr4.

The first inactive area can be in the first active area and the second inactive area can be in the second active area.

If the letterbox upper limit value detected from the current image belongs to the first active area, the comparison unit can determine that the letterbox upper limit value is a valid detection value.

If the letterbox lower limit value is within the second active area, the comparison unit can determine that the letterbox lower limit value is a valid detection value.

The adaptive output unit may further include a decision unit to output the letterbox upper limit value and the letterbox lower limit value of the previous image to the scaling unit if a difference between the detected letterbox upper limit value and the detected letterbox lower limit value is greater than a predetermined threshold and either the letterbox upper limit or the letterbox lower limit is not valid is.

The decision unit can be located between the comparison unit and the scaling unit.

The foregoing and / or other aspects of the present general inventive concept may also be accomplished by providing an aspect ratio conversion method comprising detecting letterbox boundaries of a current input image, determining whether the letterbox boundaries are valid and executing the letterbox boundaries if these are valid, adjusting the size of a substantial image area to fit (fit) within the size of a display of an image device based on the output letterbox limits.

The letterbox limit values ​​can include a letterbox upper limit value and a letterbox lower limit value.

Output of the letterbox boundary values ​​may include setting threshold values ​​dr_a, dr_b, drl, dr2, dr3 and dr4 corresponding to the size of the current input image, setting a first inactive area and a second inactive area in a first active area and a second active area located above a previous letterbox upper limit value and below a previous letterbox lower limit value, based on the previous letterbox upper limits and letterbox lower limits detected from a previous image and the threshold values ​​dr_a and dr_b provided when setting the threshold values ​​and setting whether the letterbox upper limit value is detected in the current image, associated with the first inactive area and whether the letterbox lower limit value detected in the current image is associated with the second active area and determining whether the letterbox upper limit values ​​and lower limit values ​​detected in the current image are valid.

Widths of the first and second inactive regions can be determined by the threshold values ​​dr_a and dr_b.

An image center portion of the current input image to which the substantial signal is input may overlap the first and second inactive areas.

The width of the first active region can be determined by the first and second threshold values ​​dr1 and dr2 and a width of the second active region can be determined by the third and fourth threshold values ​​dr3 and dr4.

The first inactive area can be in the first active area and the second inactive area can be in the second active area.

If the letterbox upper limit value detected in the current image is associated with the first active area, determining whether the letterbox upper limit values ​​and letterbox lower limit values ​​detected in the current image are valid includes determining that the letterbox upper limit value is a valid detection value.

If the letterbox lower limit value detected from the current image is associated with the second active area, determining whether the letterbox upper limit and letterbox lower limit values ​​detected in the current input image is valid includes determining that the letterbox lower limit value is a valid detection value.

The foregoing and / or other aspects of the present general inventive concept may also be accomplished by providing an apparatus for converting an input image having a first aspect ratio into an image to fit (fit) within a screen with a second aspect ratio, the apparatus comprising a letterbox boundary detecting unit for detecting a first letterbox boundary and a second letterbox boundary value of an input image signal having a first aspect ratio displayed on a screen having a second aspect ratio, an adaptive output unit for selectively the first letterbox limit value and a previous first letterbox limit value, and outputting one of the second letterbox boundary value and a previous second letterbox boundary value according to the first and second letterbox boundary values ​​and corresponding reference values, and an image converting unit to calculate the first aspect ratio of the input image signal using the received first and second letterbox boundaries and to convert the input image signal to another image that fits within the second aspect ratio screen.

The foregoing and / or other aspects of the present general inventive concept may also be accomplished by providing an adaptive output unit used in an apparatus for converting input images having an aspect ratio calculated based on letterbox boundary values with a predetermined aspect ratio, the adaptive output unit comprising a boundary area setting unit to define an imaged image area having a predetermined aspect ratio, wherein a first inactive area has a first inactive area width within the imaged image area and a second inactive area has a second inactive area width within the imaged image area and a decision unit for a first detected letterbox boundary value and a second detected letterbox boundary value that fits within the width or receive the height of the imaged image area and to output the first detected letterbox limit if the first detected letterbox boundary values ​​are outside the first inactive area and to output the second detected letterbox boundary values ​​if the second detected letterbox boundary values ​​are outside the second inactive area.

The foregoing and / or other aspects of the present general inventive concept may also be accomplished by providing a method of converting input images having a first width to height ratio into an image to fit within a screen having a second width to height ratio , the method comprising detecting a first letterbox boundary value and a second letterbox boundary value of an input image signal having a first aspect ratio displayed on a screen having a second aspect ratio, selectively outputting the first letterbox boundary value on a previous first letterbox boundary value according to the first and second letterbox boundary values ​​and corresponding reference values ​​and selectively outputting the second letterbox boundary values ​​and the previous second letterbox boundary values ​​according to the first and second letterbox boundary values ​​and corresponding reference values ​​and calculating of the first aspect ratio of the input image signal utilizing the received first and second letterbox boundaries and converting the input image signal into another image signal that fits within the second aspect ratio screen.

The foregoing and / or other aspects of the present general inventive concept may also be accomplished by providing a method for selectively outputting detected letterbox boundary values ​​comprising defining an imaged image area with a predetermined aspect ratio, a first inactive area with a first inactive area width within the imaged image area and a second inactive area with a second inactive area width within the imaged image area, detecting first and second letterbox boundaries of the input image that fits within the width or height of the imaged image area and outputting the first detected letterbox boundaries if the first detected letterbox boundary value has a value not associated with the first inactive area and the second detected letterbox limits if the second inactive area has a value that does not belong to the second inactive area.

BRIEF DESCRIPTION OF THE DRAWINGS

These and / or other aspects and advantages of the present general inventive concept will be clearly and better understood from the following description of the embodiment taken in conjunction with the accompanying drawings, in which:

Figure 1 is a block diagram showing an apparatus for converting the aspect ratio according to an embodiment of the present general inventive concept;

Figure 2 is a block diagram showing an adaptive output unit of the device of Figure 1;

Figures 3A and 3B are views showing active and inactive areas used to determine if letterbox boundary values ​​are valid; Figure 4 is a flowchart illustrating a method of converting an aspect ratio according to an embodiment of the present general inventive concept; and FIG. 5 is an exemplary view showing a conversion state from an image with letterbox areas to an image without letterbox areas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Here, reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are shown in the accompanying drawings, in which like reference numbers refer to like elements. The embodiments are described below in order to explain the present general inventive concept with reference to the figures.

Figure 1 is a block diagram showing an aspect ratio conversion apparatus according to an embodiment of the present general inventive concept. In Figure 1, device 100 has a letterbox boundary detecting unit 10, an adaptive unit 20 and a scaling unit 30.

The letterbox boundary detecting unit 10 detects one or more letterbox boundary values ​​of one or more letterbox areas of a current input image. The current image may include an image center portion and the letterbox areas. One or more letterbox boundary values ​​represent values ​​between the image center portion and the respective letterbox areas.

The adaptive output unit 20 determines whether the detected letterbox limits of the current input image are valid. The adaptive output unit 20 outputs the letterbox limits of the current input image if the detected letterbox limits are valid and outputs previous letterbox limits of the previous image if the detected letterbox values ​​are not valid. When the detected letterbox limit value is associated with a value of an active area, it is determined that the detected letterbox value is valid. When the detected letterbox boundary value is not associated with the value of the active area, but a value of an inactive area, it is determined that the detected letterbox boundary value is not valid. The active area represents an area comprising a letterbox. The inactive area represents an area that does not include an object image. For example, when a subtitle or logo is in the letterbox and the letterbox boundary values ​​correspond to a boundary between the image center portion and the letterbox is related to the value of the active area, the letterbox value is determined to be valid.

Figure 2 is a block diagram showing the adaptive output unit 20 of the device 100 of Figure 1. In Figure 2, the adaptive output unit 20 has a threshold setting unit 22, an inactive area setting unit 24, and a comparison unit 26. Furthermore, the adaptive output unit 20 may include a decision unit 28, although the decision unit 22 may be an optional component of the adaptive output unit 20, the decision unit 28 may further verify whether output values ​​of the comparison unit 26 are valid. The decision unit 28 can confirm that the detected letterbox boundary values ​​are valid if the difference between the letterbox boundary value is substantially equal to the predetermined value representing the width of a current input image. If the difference is not substantially equal to the predetermined value, the decision unit 28 may invalidate the detected letterbox boundary values. Furthermore, if only one of the detected letterbox limits is valid, a decision unit 28 can invalidate the detected letterbox limits.

The threshold setting unit 22 sets input parameters DR_A, DR_B, DR1, DR2, DR3 and DR4 to optimized threshold values ​​dr_a, dr_b, drl, dr2, dr3 and dr4 depending on the size and aspect ratio of one or more input images. The optimized threshold values ​​dr_a and dr_b are used to determine the widths of one or more inactive regions and first, second, third and fourth threshold values ​​dr1, dr2, dr3 and dr4 are used to determine the widths of one or more active regions. Figure 3 illustrates the active and inactive areas used to determine if the detected letterbox boundary values ​​are valid. In Figure 3A, the active areas are a first active area 40a and a second active area 40b, and the inactive areas are a first inactive area 50a and a second inactive area 50b. The first inactive area 50a can be located between the first active areas 40a, and the second inactive area 50b can be located between second active areas 40b. The width of a first active area 40a is determined by the first threshold value dr1 and the second threshold value dr2, and the width of the second active area 40b is determined by the third threshold value dr3 and the fourth threshold value dr4. The width represents the dimension of each area in a direction along which the active area, the inactive area, and the image center portion are placed on a screen of the image.

Furthermore, the threshold values ​​dr_a and dr_b determine the existence of the first inactive region 50a and the second inactive region 50b interposed between the first and second active regions 40a and 40b, respectively.

The inactive area setting unit 24 sets the first and second inactive areas 50a and 50b within the first and second active areas 40a and 40b located above or below previous letterbox limit values, respectively, based on each letterbox limit value detected from a previous image and the threshold values ​​dr_a and dr_b provided from the threshold setting unit 22.

The comparison unit 26 has first and second comparators 26a and 26b. The first comparator 26a decides whether a letterbox upper limit value detected in the current image belongs to the first active area 40a and the second comparator 26b judges whether a letterbox lower limit value detected in the current image belongs to the second active area 40b. The comparator 26 determines whether the letterbox limit values ​​detected in the current image are valid according to the results of the comparators 26a and 26b. A detected letterbox boundary value is valid if the detected letterbox boundary value corresponds to the value of an active area. If the detected letterbox boundary value does not correspond to the value of the active area, but a value of the inactive area, the detected letterbox value is not valid. That is, if the letterbox upper limit value detected in the current image belongs to the first active area 40a, the comparison unit 26 decides that the detected letterbox upper limit value of the current input image is a valid detection value and transmits the detected letterbox upper limit value of the current input image. scaling unit 30. If the letterbox lower limit value detected in the current input image belongs to the second active area 40b, the comparison unit 26 decides that the detected letterbox lower limit value of the current input image is a valid detection value and transmits the detected letterbox lower limit value of the current input image to scaling unit 30.

Furthermore, as shown in Fig. 3B, if the detected letterbox upper limit value of the current input image belongs to the first inactive area 50a, the comparator 26 decides that the current detected letterbox upper limit value is not the valid detection value. If the detected letterbox lower limit value of the current input image belongs to the second inactive area 50b, it decides the comparison unit 26 that the current detected letterbox lower limit value is not the valid detection value. As described above, if either the detected letterbox upper limit value or the detected letterbox lower limit value of the current input image is not the valid detection value, the comparator unit 26 supplies the decision unit 28 with the letterbox upper limit value or the letterbox lower limit value, measured from a previous image.

The scaling unit 30 adjusts the size of an image so that a substantial image area (image center portion) except the letterbox areas fits within the size (fits the size) of the display of the display device, based on the letterbox limits provided from the selective output unit 20.

As shown in Figure 2, the selective output unit 20 may further include the decision unit 28 between the comparison unit 26 and the scaling unit 30 to further check an output value of the comparison unit 26.

As described above, if the decision unit 28 is included in the adaptive output unit 20, the decision unit 28 decides a final output depending on the positions of the upper letterbox limit and the lowercase letterbox value received from the comparator 26.

That is, if a difference between the letterbox upper limit value and the letterbox lower limit value is greater than a predetermined threshold value or one of the letterbox upper limit values ​​or the letterbox lower limit values ​​is not valid, the decision unit 28 invalidates changes of the letterbox limit value and outputs the letterbox limit values ​​of the previous image to the scaling unit 30.

Figure 4 is a flowchart showing the method of converting an aspect ratio according to an embodiment of the present general inventive concept. Referring to Figures 1, 2 and 4, the letterbox boundary detecting unit 10 first detects one or more letterbox boundary values ​​of a current input image (operation S410).

Described below is a method for detecting limit values ​​of letterbox areas according to an embodiment of the present general inventive concept. An average pixel value is calculated over a dark strip portion and, if a difference between the calculated average pixel value and the pixel value of a current pixel is less than a predetermined threshold value D1, the method detects that the current pixel is a dark pixel. If the detected dark pixels appear to be consecutive, the detected dark pixels form a length (length) of the dark pixels defined as black run-length (BRL).

If a value of BRL is greater than a predetermined second threshold value D2, that is, if the length of the consecutive dark pixels forming a black strip of a current line is greater than a certain length, the line of an input image is detected is in a letterbox area. After this, the lines detected as being in the letterbox areas are used to determine the letterbox boundary values. That is, if a line at the same position of an input image is detected as one of the letterbox boundaries in more than a predetermined number of times, the position of the line is eventually detected as the letterbox boundary of the input image and an inactive area is positioned accordingly by the inactive area setting unit 24.

The above-described method for detecting letterbox areas is applied to the present embodiment, but other general methods can be used to detect the letterbox boundaries of the letterbox areas.

If a letterbox limit of a current input image is detected in the operation S410, the threshold setting unit 22 sets the input parameters DR_A, DRAB, DR1, DR2, DR3 and DR4 to the threshold values ​​depending on the input image (operation S420).

Here, the threshold setting unit 22 can set the input parameters to preset values ​​corresponding to the size of the input image and an input image width-height ratio or via values ​​calculated proportional to the size of the input image.

Here, the optimized threshold values ​​dr_a and drab are used to determine the widths of the inactive regions and the first through fourth threshold values ​​dr1, dr2, dr3 and dr4 are used to determine the widths of the active regions.

The inactive area setting unit 24 sets the first and second inactive areas 50a and 50b in the first and second active areas 40a and 40b located above and below an earlier letterbox boundary value based on letterbox boundary values ​​detected in a previous image and the predetermined threshold values ​​dr_a and drab provided from the threshold setting unit 22 (operation S430) in. Here, the inactive area setting unit 24 controls the image center portion into which the substantial image signal area is input to be adjusted to overlap the inactive areas. As mentioned above, the wide width inactive regions 40a and 40b are set to overlap an image center portion into which the substantial image signal is input to stably implement an autowide function by reducing changes in an image center portion as it is very possible is for a dark image signal to be input into a center part of an image.

Then, the first comparator 26a of the comparator 26 determines whether the letterbox upper limit value detected in the current input image belongs to the first active area 40a and the second comparator 26b determines whether the letterbox lower limit value detected in the current input image belongs to the second active area (operation S440).

As a result of the determination, the comparison unit 26, if the letterbox boundaries detected in the current input image belong to one of the active areas (operation S450), the detected letterbox boundaries of the current image are valid detection values ​​and enter the letterbox boundaries of the current input image to the decision unit 28 (operation S470).

Further, if the letterbox boundary values ​​detected in the current image belong to one of the inactive areas, it is further determined that the detected letterbox boundary values ​​are not valid detection values, and the comparison unit 26 outputs the letterbox boundary values ​​measured in a previous image to the decision unit 28 (operation S480).

Figure 5 is an exemplary view showing a conversion by the scaling unit from an image with letterbox areas to an image without letterbox areas. In Figure 5, the scaling unit 30 adjusts the substantial image area by scaling and expanding the substantial image area and changing the aspect ratio to fit it within the size of the display of an image device. The scaling unit performs the conversion based on the letterbox boundaries (O_OPWAARTS and O_IEERWAARTS) provided from the adaptive output unit 20 (operation S490) so that the image with letterbox areas is adapted to fit the size of the display of the display device and converted to the image without letterbox areas.

As mentioned above, the present general inventive concept as valid detection values ​​determines only the letterbox limits within the active areas, thereby providing a stable auto-wide function. That is, if the detected letterbox boundaries of a current image vary slightly within the inactive areas, earlier letterbox boundaries are provided to the scaling unit, thereby preserving letterbox boundary positions and the aspect ratio conversion of the earlier image when the auto-wide function is applied. When the detected letterbox boundaries of the current image vary significantly within the active areas, the detected letterbox boundaries are provided to the scaling unit thereby adjusting the letterbox boundary positions and the aspect ratio conversion when the auto-wide function is applied.

As mentioned previously, the present general inventive concept has the advantage of providing a more stable auto-wide function by providing frequent screen width-to-height ratio changes that occur due to changes of the detected letterbox boundaries, since the present general inventive concept as valid detection values ​​only determine the letterbox limits, corresponding to the active areas when letterbox boundaries of an input image are detected and when the aspect ratio is changed adaptively.

Although some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes can be made in these embodiments without departing from the principles and essence of the general inventive concept, the scope of which is defined in the accompanying conclusions and by their equivalents.