JP5473981B2 - Image generation apparatus, image generation system, image display apparatus, computer program, and image generation method - Google Patents

Description

  The present invention relates to an image generation device that generates a composite image by superimposing gradation values of a first image and a second image at an arbitrary ratio, an image generation system that includes the image generation device, and an image display that generates the composite image. The present invention relates to an apparatus, a computer program for realizing the image generation apparatus, and an image generation method.

  In recent years, with the spread of the Internet or information terminals, instead of newspapers or books printed on paper, the use of electronic articles, electronic books and other text information or image information on a display device such as a monitor has increased. ing. When various images such as documents, drawings or photographs are displayed on a monitor, it is desirable to display them with familiar textures similar to conventional paper prints, and to reduce the burden on eyes or discomfort during browsing. ing.

  For example, when comparing a document displayed on a paper medium and a document displayed on a monitor, the document displayed on the monitor has a display resolution or contrast ratio peculiar to the display device. In general, the background has little unevenness and high brightness, while the characters are thick and dark, and the outline becomes rough, making it look dazzling and emphasized. As a result, there are many opinions that paper documents are easier to read.

  Also disclosed is an information processing apparatus capable of displaying a print result actually obtained by displaying an image obtained by combining paper image data and print data of a sheet used for printing on a print preview screen. (See Patent Document 1).

Japanese Patent No. 4429097

  However, when displaying various documents, drawings, photographs, etc. on a display device, focusing on the background image quality, a technique for improving the texture by artificially adjusting the background image quality by superimposing the filter image on the original image Has never been realized before.

  The present invention has been made in view of such circumstances, and an image generation apparatus capable of realizing an appearance like a paper medium by combining an original image and a filter image such as a paper medium by alpha blending processing. Another object of the present invention is to provide an image generation system including the image generation apparatus, an image display apparatus, a computer program for realizing the image generation apparatus, and an image generation method.

Image generating apparatus according to the first invention, each second image having a first image and the first image is different from the second gradation range in a first tone width include any gradation value gray level value of any Composite image generation means for generating a composite image by superimposing at a ratio, gradation conversion means for converting the gradation value of the composite image generated by the composite image generation means under a predetermined condition, and composition by the composite image generation means Condition changing means for changing the predetermined condition so as to compensate for the loss gradation width from the first gradation width generated as a result of generating the image .

Image generating apparatus according to the second invention, in the first invention, comprising a calculating means for calculating a gradation width before Symbol ratio and the synthesized image based on the second tone width of the second image, the condition changing means The predetermined condition is changed on the basis of the gradation value calculated by the calculating means .

  In the image generation apparatus according to a third aspect of the present invention, in the first or second aspect, the condition changing means extends the gradation width of the composite image so that the gradation width of the composite image becomes the gradation width of the first image. Alternatively, the predetermined condition is changed so as to be compressed.

  An image generation apparatus according to a fourth invention is the image generation device according to any one of the first invention to the third invention, wherein the gradation converting means has a lookup table for converting an input gradation value into an output gradation value, The condition changing means is configured to change the predetermined condition by rewriting an output gradation value of the lookup table.

  An image generation apparatus according to a fifth aspect of the present invention is the adjustment unit for adjusting a contrast ratio of an output image obtained by converting a gradation value by the gradation conversion unit in any one of the first to fourth aspects. It is characterized by providing.

  An image generation system according to a sixth aspect of the present invention is an image generation apparatus according to any one of the first to fourth aspects of the present invention, and an image for displaying an output image obtained by converting a gradation value by the image generation apparatus In the image generation system including the display device, the image display device includes an adjusting unit that adjusts a contrast ratio of the output image.

According to a seventh aspect of the present invention, there is provided the image display device according to the present invention, wherein the gradation values of the first image having the first gradation width including an arbitrary gradation value and the second image having the second gradation width different from the first image are arbitrarily determined. Composite image generation means for generating a composite image by superimposing at a ratio, gradation conversion means for converting the gradation value of the composite image generated by the composite image generation means under a predetermined condition, and composition by the composite image generation means A condition changing means for changing the predetermined condition to compensate for the lost gradation width from the first gradation width generated as a result of generating the image, and a contrast ratio of the output image whose gradation value is converted by the gradation converting means. Adjusting means for adjusting.

A computer program according to the eighth invention, the computer, the second image each gradation value having the first image and the first image is different from the second gradation range in a first tone width including any gradation values A step of generating a composite image by superimposing at an arbitrary ratio, a step of converting a gradation value of the generated composite image under a predetermined condition, and a loss floor from the first gradation width generated as a result of generating the composite image And a step of changing the predetermined condition to compensate for the adjustment range .

Image generating method according to the ninth invention, each second image having a first image and the first image is different from the second gradation range in a first tone width include any gradation value gray level value of any A step of generating a composite image by superimposing at a ratio, a step of converting a gradation value of the generated composite image under a predetermined condition, and a loss gradation width from the first gradation width generated as a result of generating the composite image And a step of changing the predetermined condition to compensate .

In the first invention, the eighth invention, and the ninth invention, the composite image generating means superimposes the gradation values of the first image (original image) and the second image (filter image) at an arbitrary ratio and combines them. Generate an image. For example, the gradation value of an arbitrary pixel of the original image is A, the gradation value of the corresponding pixel of the filter image is B, the gradation value of the corresponding pixel of the composite image is C, and the ratio (also referred to as transmittance) is α. When the gradation value of the composite image can be obtained by C = (1-α) × a + α × B. The gradation width, called the tonal range, in the range of from the maximum tone to the minimum tone. Note that the gradation width is not necessarily limited to the gradation width in the range of 0 to 255 when the full scale of the image is 0 to 255 gradation, for example. The range up to the key (may be narrower than full scale). By calculating the gradation width of the composite image, the dynamic range lost with the generation of the composite image can be obtained. The dynamic range is a displayable gradation range and indicates display capability. Note that the gradation width of the composite image can be obtained from the gradation width and ratio of the original image (first image), the gradation width of the filter image (second image), and the like.

Condition changing means changes the predetermined condition of the gradation conversion means for converting the gradation values of the synthetic image at a predetermined condition. The predetermined condition is a condition for associating the input gradation value to the gradation converting means with the output gradation value from the gradation converting means, and changing means changing the associated output gradation value. To do. The tone conversion means converts the tone value of the composite image to generate an output image. The gradation conversion can also be referred to as gradation correction. Then, the condition changing means calculates the dynamic range lost when converting the gradation value of the composite image by the gradation conversion means based on the gradation width of the composite image, that is, the dynamic range lost with the generation of the composite image. The predetermined condition is changed so as to compensate (control the conversion process). By changing predetermined conditions to compensate for the loss of dynamic range in the composite image, the “wrinkle” or “unevenness” pattern of the filter image is superimposed on the original image of the monitor, making the monitor look closer to paper Is possible. In addition, the graphic board LUT control function can be used to correct the dynamic range loss of the image synthesized by the alpha blending method, and the synthesized image displayed on the monitor becomes brighter or darker than the original image. Can be prevented, and the dynamic range of the original image can be faithfully reproduced.

  In the second invention, for example, when the gradation width of the original image (first image) is 0 to 255, the calculation means calculates the composite image based on the ratio and the gradation width of the second image (filter image). The gradation width is calculated. For example, if the gradation width of the original image (first image) is 0 to 255, the gradation width of the filter image (second image) is 144 to 240, and the ratio α is 0.2, the gradation width of the composite image is 29 to 252. It becomes. The minimum gradation 29 of the composite image can be obtained by 0 × (1−0.2) + 144 × 0.2, and the maximum gradation 252 of the composite image is 255 × (1−0.2) + 240 × 0. .2 can be obtained. In addition, when the gradation width of the original image is different from the above, when the gradation width of the filter image is different from the above, or when the ratio is different, the same can be obtained.

  In the third invention, the condition changing means changes the predetermined condition so as to expand or compress the gradation width of the composite image so that the gradation width of the composite image becomes the gradation width of the first image (original image). For example, when the gradation width of the original image is 0 to 255 and the gradation width of the composite image is 29 to 252, the gradation value in the range of the gradation width 29 to 252 of the composite image is converted. By changing the tone value (output gradation value), the gradation width of the output image (composited composite image) obtained by extending the gradation width of the composite image is set to 0 to 255. If the gradation width of the filter image is wider (larger) than the gradation width of the original image, the gradation width of the composite image may be compressed. Thereby, the dynamic range of the original image can be reproduced.

  In the fourth invention, the gradation converting means has a lookup table for converting the input gradation value to the output gradation value, and the condition changing means rewrites the output gradation value of the lookup table. Change predetermined conditions. This makes it easy to compensate for the loss of dynamic range during image composition by simply rewriting the output value of an existing lookup table that performs gradation conversion (gradation correction) without the need for dedicated hardware. be able to.

  According to the fifth aspect of the present invention, there is provided adjusting means for adjusting the contrast ratio of the output image (composited image after gradation conversion) obtained by converting the gradation value by the gradation converting means. The contrast ratio is the luminance at the maximum gradation: the luminance at the minimum gradation. The contrast ratio of the paper medium is, for example, 6-7: 1 for newspapers, 10-11: 1 for copy paper (recycled paper), Copy paper (ordinary white paper) is about 30: 1 and printer photo paper is about 50: 1. By adjusting the contrast ratio, for example, when a paper pattern representing paper “wrinkles” or “unevenness” is used as the filter image (second image), the output image is displayed close to the paper medium. It becomes possible to do.

  In the sixth aspect of the invention, the image generation apparatus includes the above-described image generation apparatus and an image display apparatus that displays an output image obtained by gradation conversion by the image generation apparatus. The image display apparatus has a contrast ratio of the output image. Adjustment means for adjusting is provided. Thereby, for example, when a paper pattern representing “wrinkle” or “unevenness” of paper is used as the filter image (second image), the composite image is formed by superimposing the filter image on the original image at a desired ratio. The dynamic range of the original image can be reproduced even when generating the image, and the image can be brought close to paper even when the output image is displayed.

  In the seventh invention, the composite image is generated by superimposing the gradation values of the first image (original image) and the second image (filter image) at an arbitrary ratio. For example, the gradation value of an arbitrary pixel of the original image is A, the gradation value of the corresponding pixel of the filter image is B, the gradation value of the corresponding pixel of the composite image is C, and the ratio (also referred to as transmittance) is α. Then, the gradation value of the composite image can be obtained by C = (1−α) × A + α × B. The calculation means calculates the gradation width of the composite image. The gradation width means a gradation range, which is a range from the maximum gradation to the minimum gradation. Note that the gradation width is not necessarily limited to the gradation width in the range of 0 to 255 when the full scale of the image is 0 to 255 gradation, for example. The range up to the key (may be narrower than full scale). By calculating the gradation width of the composite image, the dynamic range lost with the generation of the composite image can be obtained. The dynamic range is a displayable gradation range and indicates display capability. Note that the gradation width of the composite image can be obtained from the gradation width and ratio of the original image (first image), the gradation width of the filter image (second image), and the like.

  The condition changing means changes the predetermined condition of the gradation converting means for converting the gradation value of the composite image under a predetermined condition based on the calculated gradation width. The predetermined condition is a condition for associating the input gradation value to the gradation converting means with the output gradation value from the gradation converting means, and changing means changing the associated output gradation value. To do. The tone conversion means converts the tone value of the composite image to generate an output image. The gradation conversion can also be referred to as gradation correction. Then, the condition changing means calculates the dynamic range lost when converting the gradation value of the composite image by the gradation conversion means based on the gradation width of the composite image, that is, the dynamic range lost with the generation of the composite image. The predetermined condition is changed so as to compensate (control the conversion process). By changing predetermined conditions to compensate for the loss of dynamic range in the composite image, the “wrinkle” or “unevenness” pattern of the filter image is superimposed on the original image of the monitor, making the monitor look closer to paper Is possible. In addition, the graphic board LUT control function can be used to correct the dynamic range loss of the image synthesized by the alpha blending method, and the synthesized image displayed on the monitor becomes brighter or darker than the original image. Can be prevented, and the dynamic range of the original image can be faithfully reproduced.

  The adjusting means adjusts the contrast ratio of the output image (composited image after gradation conversion) obtained by converting the gradation value by the gradation converting means. The contrast ratio is the luminance at the maximum gradation: the luminance at the minimum gradation. The contrast ratio of the paper medium is, for example, 6-7: 1 for newspapers, 10-11: 1 for copy paper (recycled paper), Copy paper (ordinary white paper) is about 30: 1 and printer photo paper is about 50: 1. By adjusting the contrast ratio, for example, when a paper pattern representing paper “wrinkles” or “unevenness” is used as the filter image (second image), the output image is displayed close to the paper medium. It becomes possible to do.

  According to the present invention, the “wrinkle” or “unevenness” pattern of the filter image is superimposed on the original image of the monitor, so that the appearance of the monitor can be brought close to paper. In addition, the graphic board LUT control function can be used to correct the dynamic range loss of the image synthesized by the alpha blending method, and the synthesized image displayed on the monitor becomes brighter or darker than the original image. Can be prevented, and the dynamic range of the original image can be faithfully reproduced. Furthermore, by adjusting the contrast ratio, the output image can be displayed in a state close to a paper medium.

1 is a block diagram illustrating an example of a configuration of an image generation system according to a first embodiment. It is explanatory drawing which shows an example of an alpha blending technique. It is explanatory drawing which shows an example of an input image. It is explanatory drawing which shows an example of a filter image. It is explanatory drawing which shows an example of a synthesized image. FIG. 6 is an explanatory diagram illustrating a first example of control of gradation conversion processing by the image generation device according to the first embodiment. It is explanatory drawing which shows an example of an output image. FIG. 10 is an explanatory diagram illustrating a second example of gradation conversion processing control by the image generation apparatus according to the first embodiment. It is explanatory drawing which shows the example of the output image in the case of the control method of FIG. FIG. 11 is an explanatory diagram illustrating a third example of control of gradation conversion processing by the image generation device according to the first embodiment. FIG. 10 is an explanatory diagram illustrating a fourth example of control of gradation conversion processing by the image generation device according to the first embodiment. FIG. 10 is an explanatory diagram illustrating a fifth example of gradation conversion processing control by the image generation apparatus according to the first embodiment. FIG. 10 is an explanatory diagram illustrating a sixth example of control of gradation conversion processing by the image generation device according to the first embodiment. It is a conceptual diagram which shows an example of the gradation brightness | luminance table of the image display apparatus of this Embodiment. It is a flowchart which shows the procedure of the LUT control process by the image generation apparatus of this Embodiment. FIG. 6 is a block diagram illustrating an example of a configuration of an image display device according to a second embodiment. 10 is a block diagram illustrating an example of a configuration of an image generation device according to Embodiment 3. FIG.

Embodiment 1
Hereinafter, an image generation apparatus, an image generation system, an image display apparatus, a computer program, and an image generation method according to the present invention will be described with reference to the drawings illustrating embodiments. FIG. 1 is a block diagram illustrating an example of a configuration of an image generation system 100 according to the first embodiment. The image generation system 100 includes an image generation device 10, an image display device 20, and the like. The image generation device 10 can be realized by, for example, a personal computer PC.

  The image generation device 10 includes a storage unit 12 that stores an original image (hereinafter also referred to as an input image) as a first image and a filter image 121 as a second image, a control unit 13 that controls the image generation device 10, and an input image. A combined image generating unit 14 as a combined image generating unit for combining the filter image and the filter image, an LUT (look-up table) converting unit 15 as a gradation converting unit (hereinafter also referred to as a gradation correcting unit), and a user ratio (transmission) And an operation unit 16 for setting a value of the ratio.

  The control unit 13 has a function as a condition changing unit that changes a predetermined condition of the gradation converting unit (LUT converting unit 15). The predetermined condition is a condition for associating the input tone value to the LUT converter 15 and the output tone value from the LUT converter 15, and changing means changing the associated output tone value To do. In addition, the control unit 13 includes a gradation range calculation unit 131 as a calculation unit that calculates a gradation value width, a gain calculation unit 132 as a ratio calculation unit, an offset calculation unit 133 as an offset calculation unit, and the like. The gradation range calculation unit 131, the gain calculation unit 132, and the offset calculation unit 133 may be separated from the control unit 13.

  The storage unit 12 stores a plurality of filter images 121 in advance. The filter image 121 is, for example, an image expressing a paper medium, and is a paper pattern image expressing “wrinkle” or “unevenness” of paper. By operating the operation unit 16, the user can display the stored sample image (thumbnail image) of the filter image 121 on the screen and select a desired filter image. Thereby, the user can synthesize the filter image with the input image displayed on the image display device 20, and can reproduce the appearance of the printed matter on the paper medium on the monitor.

  Further, the user can set the ratio α to an arbitrary value in the range from 0 to 1 by operating the operation unit 16. When the ratio (transmittance) α = 0, the original image is completely opaque, and when α = 1, the original image is completely transparent. That is, by superimposing the filter image on the opaque original image and making it close to transparency, it is possible to reproduce the texture when the original image is superimposed on the background image such as paper and ink is superimposed on the paper.

  The composite image generation unit 14 generates a composite image by superimposing the input image and the filter image 121 using a so-called alpha blending technique, and outputs the generated composite image to the LUT conversion unit 15 under the control of the control unit 13. To do.

  FIG. 2 is an explanatory diagram showing an example of alpha blending technology. The input image (original image, first image) is A, the filter image (second image) is B, and the composite image is C. If the ratio set by the user is α, the composite image can be obtained by C = (1−α) × A + α × B. Reference signs A, B, and C mean the gradation values of the respective pixels on (corresponding to) the same coordinates of the respective images.

  For example, as shown in FIG. 2, when the gradation value of the input image A is 0, the gradation value of the filter image B is 128, and the ratio α is 0.5, the gradation value of the composite image is 0 × (1 −0.5) + 128 × 0.5 = 64. Further, if the gradation value of the input image A is 255, the gradation value of the filter image B is 128, and the ratio α is 0.5, the gradation value of the composite image is 255 × (1−0.5) + 128 ×. 0.5 = 192.

  FIG. 2 shows how the gradation value of each pixel of the input image changes when it is combined with the filter image. For example, the gradation value 0 of the input image A becomes a gradation value 64 in the composite image, and gradation floating (lightening) occurs. On the other hand, the gradation value 255 of the input image A becomes a gradation value 192 in the composite image, and gradation depression (darkening) occurs.

  Next, image composition of the input image and the filter image will be described in detail. FIG. 3 is an explanatory diagram showing an example of an input image, FIG. 4 is an explanatory diagram showing an example of a filter image, and FIG. 5 is an explanatory diagram showing an example of a composite image. In the following description, for simplification, a 6 × 6 pixel block will be described. The numerical value in the block is a gradation value. As shown in FIG. 3A, the gradation values of the input image are 0, 48, 96, 144, 192, 255. That is, since the minimum gradation value of the input image is 0 and the maximum gradation value is 255, the gradation width (gradation range) is 0 to 255. Note that the gradation value of each pixel of the input image can take any value from 0 to 255, but for the sake of simplicity, in the example of FIG. 3A, the values of 0, 48, 96, 144, 192, and 255 are set. Illustrated.

  In FIG. 3B, when the LUT has a linear characteristic with an offset F = 0 and a gain G = 1, the horizontal axis indicates the gradation range of the input image (the gradation range before passing through the LUT), and the vertical axis indicates the input image. The gradation range (gradation range after passing through the LUT) of the output image that faithfully outputs the gradation is shown. That is, an input image with a gradation range of 0 to 255 becomes an output image with a gradation range of 0 to 255 as it is.

  As shown in FIG. 4A, the gradation values of the filter image are 144, 192, and 240 as an example. That is, since the minimum gradation value of the filter image is 144 and the maximum gradation value is 240, the gradation width (gradation range) is 144 to 240. As shown in FIG. 4A, it can be seen that the dynamic range of the filter image representing the paper pattern is extremely narrow (smaller) than the gradation range (0 to 255) of the input image.

  In FIG. 4B, when the LUT has a linear characteristic with an offset F = 0 and a gain G = 1, the horizontal axis indicates the gradation range of the filter image (the gradation range before passing through the LUT), and the vertical axis indicates the filter image. The gradation range (gradation range after passing through the LUT) of the output image that faithfully outputs the gradation is shown. That is, the filter image with the gradation range of 144 to 240 becomes the output image with the gradation range of 144 to 240 as it is.

  The composite image shown in FIG. 5A is obtained by combining the input image of FIG. 3A and the filter image of FIG. 4A at a ratio α = 0.2. That is, assuming that the input image is A, the filter image is B, and the combined image is C, C = (1−0.2) × A + 0.2 × B. By applying the gradation value of an arbitrary pixel of the input image and the gradation value of the corresponding pixel of the filter image to A and B, respectively, the gradation value of the corresponding pixel of the composite image can be obtained.

  As described above, if the ratio α = 0.2, as shown in FIG. 5A, the gradation value of each pixel of the composite image is 29, 38, 48,... 252 and the gradation range of the composite image is 29-252. In this case, since the gradation range of the input image is 0 to 255, the gradation range of the composite image is narrowed because the gradation range of the input image is not output correctly, and thus the dynamic range is lost.

  In FIG. 5B, when the LUT has a linear characteristic with an offset F = 0 and a gain G = 1, the horizontal axis indicates the gradation range of the composite image before passing through the LUT, and the vertical axis indicates the output image after passing through the LUT. Since the composite image that indicates the gradation range and loses the dynamic range is output as it is, the dynamic range of the composite image is not lost, but the dynamic range of the input image that is the original image remains lost. That is, as long as the LUT conversion condition is not changed, even if an input image (original image) of 0 to 255 full scale is input, as long as the gradation range of the composite image is 29 to 252, the output image after passing through the LUT The gradation range is 29-252.

  For this reason, if the composite image is output as it is through the LUT conversion unit 15, the problem of gradation floating or gradation sinking occurs as compared with the input image (original image), and the image has a low contrast. End up. In the present embodiment, the control unit 13 changes the predetermined condition of the LUT conversion unit 15 (controls the gradation conversion process), thereby solving the above-described problem and synthesizing the input image and the filter image. But it can reproduce the dynamic range of the input image. Hereinafter, this point will be described.

  First, the gradation range calculation unit 131 calculates the gradation width of the composite image (for example, the difference between the maximum gradation and the minimum gradation, so-called dynamic range).

  More specifically, the gradation range calculation unit 131 calculates the gradation width of the composite image based on the ratio α and the gradation width of the filter image. For example, if the gradation width of the input image is 0 to 255, the gradation width of the filter image is 144 to 240, and the ratio α = 0.2, the gradation width of the composite image is 29 to 252. The minimum gradation 29 of the composite image can be obtained by 0 × (1−0.2) + 144 × 0.2, and the maximum gradation 252 of the composite image is 255 × (1−0.2) + 240 × 0. .2 can be obtained. In addition, when the gradation width of the input image is different from the above, when the gradation width of the filter image is different from the above, or when the ratio is different, the same can be obtained.

  By calculating the gradation width of the composite image by the gradation range calculation unit 131, the dynamic range lost with the generation of the composite image can be obtained.

  The control unit 13 controls gradation conversion processing (gradation correction processing) by changing predetermined conditions of the LUT conversion unit 15 based on the gradation width of the composite image calculated by the gradation range calculation unit 131. The predetermined condition refers to a condition for associating the input tone value to the LUT converter 15 and the output tone value from the LUT converter 15, and the change is the associated output tone value. Is to change.

  The LUT conversion unit 15 holds an output tone value in association with an input tone value, uses the tone value of the composite image as an input tone value, and outputs an output tone value corresponding to the input tone value. By converting (correcting) the gradation value of the composite image, a composite image after gradation conversion (that is, an output image) can be generated.

  The control unit 13 performs tone conversion processing (tone correction processing) in the LUT conversion unit 15 so as to compensate for the dynamic range lost when the composite image is generated based on the tone width (tone range) of the composite image. To control. By controlling the gradation conversion process to compensate for the loss of the dynamic range in the composite image, the dynamic range of the input image can be reproduced even when the input image and the filter image are combined.

  In addition, the control unit 13 changes a predetermined condition of the LUT conversion unit 15 so as to expand or compress the gradation width of the composite image so that the gradation width of the composite image becomes the gradation width of the input image. For example, when the tone width of the input image is 0 to 255 and the tone width of the composite image is 29 to 252, the tone width of the composite image is expanded by changing a predetermined condition of the LUT conversion unit 15. The gradation width of the output image (converted composite image) obtained in this way is set to be 0-255. If the gradation width of the filter image is wider (larger) than the gradation width of the input image (original image), the gradation width of the composite image may be compressed. Thereby, the dynamic range of the input image (original image) can be reproduced.

  FIG. 6 is an explanatory diagram illustrating a first example of gradation conversion processing control by the image generation apparatus 10 according to the first embodiment. The change of the predetermined condition, that is, the control of the gradation conversion process (gradation correction process) can be realized by gain calculation, offset calculation, or the like.

  The gain calculation unit 132 calculates a change in output tone with respect to a change in input tone of the LUT conversion unit 15, that is, a gain of tone characteristics, and the control unit 13 has the gain calculated by the gain calculation unit 132. The output value of the LUT converter 15 is rewritten.

  More specifically, the gain calculation unit 132 calculates the ratio of the gradation width (maximum gradation−minimum gradation) of the input image to the gradation width (maximum gradation−minimum gradation) of the composite image as the gain G. For example, when the maximum gradation value of the input image is 255 and the minimum gradation value is 0, and the maximum gradation value of the composite image is 252 and the minimum gradation value is 29, the gain G is G = (255-0) / (252-29) = 1.14350.

  The control unit 13 changes a predetermined condition of the LUT conversion unit 15 by changing the gain (ratio) of the gradation width of the output gradation with respect to the gradation width of the input gradation of the LUT conversion unit 15 to the calculated gain G. Controls gradation conversion processing. Since the gain of the LUT conversion unit 15 is the gain characteristic of the output gradation with respect to the input gradation, the control unit 13 changes the gain characteristic of the gradation conversion to the calculated gain G, thereby The gradation conversion process is controlled. As a result, even when the gradation width is expanded (changed) to compensate for the loss of the dynamic range, the change in the output gradation with respect to the change in the input gradation when the composite image is subjected to gradation conversion is expressed by the gain G (ratio). The brightness level of the output image (the synthesized image after gradation conversion) can be made equal to the brightness level of the original image.

  The offset calculation unit 133 calculates the minimum gradation value of the composite image as the offset F. For example, if the minimum gradation value of the composite image is 29, the offset F is F = 29.

  Based on the gain G calculated by the gain calculation unit 132 and the offset F calculated by the offset calculation unit 133, the control unit 13 determines the output gradation of the LUT conversion unit 15 as output gradation = (input gradation−F) × By setting G, a predetermined condition is changed to control the gradation conversion processing of the LUT conversion unit 15. Controlling the tone correction processing of the LUT conversion unit 15 means that, for example, the control unit 13 outputs a control command to the LUT conversion unit 15 and the LUT conversion unit 15 rewrites the output value. Note that the offset F can be either positive or negative or zero.

  Further, it may be 0 when the output value of the LUT converter 15 is smaller than 0, and 255 when it is larger than 255.

  When the LUT conversion unit 15 is operated as shown in FIG. 6 by combining the gain G and the offset F, the gradation width of the composite image remains 29 to 252 but the output image after passing through the LUT conversion unit 15 The gradation range of 0 to 255 is a full-scale dynamic range. That is, it can be seen that the dynamic range of the output image output from the LUT converter 15 is equivalent to the dynamic range of the original input image.

  FIG. 7 is an explanatory diagram showing an example of an output image. When the LUT converter 15 is operated as shown in FIG. 6, the dynamic range (gradation width) of the output image is 0 to 255 as shown in FIG. Compared with the composite image of FIG. 5, the minimum gradation value 29 of the composite image is expanded to 0, and the maximum gradation value 252 of the composite image is expanded to 255.

  FIG. 8 is an explanatory diagram illustrating a second example of control of gradation conversion processing by the image generation apparatus 10 according to the first embodiment. The difference from the example of FIG. 6 is that the gain is not changed (the gain is fixed), and the output value of the lost dynamic range is set to 0 or 255. Thus, by outputting the gradation value corresponding to the loss as black or white, the dynamic range of the output image output from the LUT conversion unit 15 may be equivalent to the dynamic range of the original input image. Recognize.

  FIG. 9 is an explanatory diagram showing an example of an output image in the case of the control method of FIG. In the case of FIG. 9 as well, as in the case of FIG. 7, the dynamic range (gradation width) of the output image is 0 to 255. In the examples of FIGS. 8 and 9, the luminance step changes greatly in the vicinity of the minimum gradation and the maximum gradation of the composite image. Therefore, the image quality of the example of FIG. This is preferable because it looks natural.

  FIG. 10 is an explanatory diagram illustrating a third example of control of gradation conversion processing by the image generation apparatus 10 according to the first embodiment. The difference from the example of FIG. 6 is that the gain is fixed only in a desired gradation range, the gradation characteristic of the input image (original image) is maintained as it is, and in the gradation range excluding the desired gradation range, FIG. The same gradation width expansion as in the control shown in FIG.

  Among the gradation values included in the input image, when there is a gradation range that should be particularly emphasized (for example, when it is necessary to match the luminance step between each gradation to the input image), the importance should be emphasized. The gain of the tone range is fixed without changing, and the tone width is expanded in the tone range outside the tone range, so that the dynamic range of the output image becomes the same as the dynamic range of the input image. The gradation range that should be emphasized can be maintained.

  In the case of FIG. 10, the control unit 13 determines the gradation width of the input gradation of the LUT conversion unit 15 in other gradation ranges excluding the required gradation range (particularly, the gradation range to be emphasized) of the input image. The correction processing is controlled by setting the ratio of the gradation width of the output gradation to the gain G calculated by the gain calculation unit 132.

  Further, the offset F in the case of FIG. 10 can be obtained in the same manner as in the case of FIG.

  FIG. 11 is an explanatory diagram illustrating a fourth example of gradation conversion control performed by the image generation apparatus 10 according to the first embodiment. The difference from the example in FIG. 6 is that non-linear expansion is performed instead of linear expansion as in FIG. In this case, the output value of the LUT converter 15 is rewritten so that the change in the output gradation with respect to the change in the input gradation has a non-linear relationship as shown in FIG.

  That is, the control unit 13 controls the gradation conversion process so that the change in the output gradation with respect to the change in the input gradation of the LUT conversion unit 15 becomes nonlinear (non-linear). As the offset, the output value in the range of the dynamic range lost due to the composite image is set to 0 or 255, as in FIG.

  FIG. 12 is an explanatory diagram illustrating a fifth example of gradation conversion control performed by the image generation apparatus 10 according to the first embodiment. The difference from the example of FIG. 6 is that a gain G ′ different from the gain G is used for the gain G calculated as in the case of FIG. Note that the offset F needs to be changed by changing the gain G to the gain G ′. In the example of FIG. 12, the input gradation for offsetting the gradation value to 0 or 255 is slightly increased (increased). Thereby, for example, when it is not necessary to match the gradation range of the input image and the gradation range of the output image, an arbitrary gradation range (contrast ratio) or output characteristics can be obtained. In the example of FIG. 12, the gain G ′ is larger than the gain G, but the present invention is not limited to this, and the gain G ′ may be smaller than the gain G.

  FIG. 13 is an explanatory diagram illustrating a sixth example of gradation conversion processing control by the image generation apparatus 10 according to the first embodiment. The difference from the first to fifth examples described above is that the gradation range is different between the input image and the filter image (the number of bits representing the gradation is different).

  For example, when the input image is an image having a 10-bit depth and the filter image is an image having an 8-bit depth, the synthesized image and the output image are obtained by normalizing the bit depth. In the following, as an example, a case where a 10-bit depth input image and an 8-bit depth filter image are combined to generate a 10-bit depth composite image, and then an 8-bit depth output image is generated will be described.

  For example, if the minimum gradation of the input image is A1 and the maximum gradation is A2, the gradation range of the input image is A1 / 1024 to A2 / 1024. If the minimum gradation of the filter image is B1 and the maximum gradation is B2, the gradation range of the filter image is B1 / 255 to B2 / 255.

  When the ratio (transmittance) is α, the gradation range of the composite image is {(1−α) × A1 / 1024 + α × B1 / 255} to {(1−α) × A2 / 1024 + α × B2 / 255. } Range. Since the dynamic range is normalized, the optimum gradation correction characteristic for an output image having an 8-bit depth is as shown in FIG. In FIG. 13, the input gradation S1 = {(1−α) × A1 / 1024 + α × B1 / 255}, and the input gradation S2 = {(1−α) × A2 / 1024 + α × B2 / 255}. Note that the output gradation for the input gradation below the input gradation S1 is 0, and the output gradation for the input gradation above the input gradation S2 is 255. The method of obtaining the input gradations S1 and S2 can be obtained from the gain G and the offset F, but can be generalized as described above.

  Next, a general calculation method of optimum gradation conversion characteristics (output value of the LUT conversion unit 15) will be described. The input image is L-bit RGB data with a resolution (H × V), and the RGB gradation values in the pixel at coordinates (i, j) are aR (i, j), aG (i, j), aB (i , J). Here, 1 ≦ i ≦ H: horizontal, 1 ≦ j ≦ V: vertical. If the RGB gradation levels normalized by the bit depth are AR (i, j), AG (i, j), and AB (i, j), respectively, AR (i, j), AG (i, j), AB (i, j) can be represented by the formulas (1) to (3), respectively.

  Similarly, the filter image is M-bit RGB data with a resolution (H × V), and the RGB gradation values at the pixel at the coordinates (i, j) are bR (i, j), bG (i, j), Let bB (i, j). Here, 1 ≦ i ≦ H: horizontal, 1 ≦ j ≦ V: vertical. Assuming that the gradation levels of RGB normalized by the bit depth are BR (i, j), BG (i, j), and BB (i, j), respectively, BR (i, j), BG (i, j), BB (i, j) can be expressed by the equations (4) to (6), respectively.

  When an input image and a filter image are alpha-blended with a ratio (transmittance) α to generate a composite image as N-bit RGB data with the same resolution (H × V), the coordinates (i, j) of the composite image The RGB gradation values in the pixel are cR (i, j), cG (i, j), and cB (i, j), respectively. Here, 1 ≦ i ≦ H: horizontal, 1 ≦ j ≦ V: vertical. If the gradation levels of RGB normalized by bit depth are CR (i, j), CG (i, j), and CB (i, j), respectively, CR (i, j), CG (i, j), CB (i, j) can be expressed by the following formulas (7) to (9).

  Further, for CR (i, j), CG (i, j), and CB (i, j), the relationships of Expressions (10) to (12) are established.

  The input image A (i, j) is an arbitrary image, and the assumed gradation range is, for example, the entire range 0 ≦ A (i, j) ≦ 1. When the gradation range is determined in advance, the range can be set instead of the entire range. Further, the filter image B (i, j) is an image that can be set (selected) by the user in advance, and the gradation range can be set as inherent X ≦ B (i, j) ≦ Y. The ratio (transmittance) α is also a value Z (α = Z) that can be arbitrarily set by the user.

  That is, the gradation range of the composite image C (i, j) can be obtained as in Expression (13) using the above-described X, Y, and Z. That is, the unused gradation range (dynamic range loss range) of the composite image is from 0 to {(1-Z) × 0 + Z × X} and from {(1-Z) × 1 + Z × Y} to 1. Therefore, in order to make the gradation range of the input image equal to the gradation range of the output image, the gradation characteristics as shown in FIGS. 6, 8, and 10 to 13 are obtained. The output value of the LUT conversion unit 15 may be rewritten.

  In addition, when the gradation range of the input image is not the entire range and any gradation range P ≦ A (i, j) ≦ Q, the unused gradation range of the composite image is changed from 0 to {( 1-Z) * P + Z * X} and {(1-Z) * Q + Z * Y} to 1. Since the ranges of X, Y, P, Q, and Z are normalized values, the values are in the range of 0 to 1.

  Further, when an arbitrary gradation range P ≦ A (i, j) ≦ Q changes with time, it is possible to rewrite the output value of the LUT converter 15 by calculating an optimal output value as needed.

  As described above, the control unit 13 controls the gradation conversion process (gradation correction process) by changing a predetermined condition by rewriting the output gradation value of the lookup table of the LUT conversion unit 15. As a result, it is possible to easily compensate for the loss of dynamic range during image composition simply by rewriting the output value of an existing lookup table that performs gradation correction without requiring dedicated hardware or the like.

  Further, the ratio can be set to a desired arbitrary value (0 to 1) by the operation unit 16. As a result, even when the images are combined at a desired ratio, the gradation conversion process is controlled based on the ratio, so that the dynamic range of the input image can be reproduced regardless of the ratio.

  The image display device 20 includes a gradation luminance table 21, a liquid crystal panel 22 that displays an output image, and the like. The liquid crystal panel 22 has, for example, a structure in which a pair of glass substrates are arranged to face each other and a liquid crystal layer that is a liquid crystal material is formed in the gap between the plurality of pixel electrodes and the pixel electrodes. A TFT having a drain connected to each other and a common electrode on the other glass substrate are provided. The gate and source of the TFT are sequentially connected to the output stages of the gate driver and source driver, respectively.

  In the liquid crystal panel 22, the on / off state of the TFT of each pixel is controlled by the gate signal input from the gate driver, and the output voltage (input level to the display panel 1) input from the source driver is set to the ON period of each pixel. When applied to the TFT, the light transmittance determined by the electro-optical characteristics of the liquid crystal substance is controlled to display an image in gradation.

  The gradation luminance table 21 is a table that defines the luminance values of R (red), G (green), and B (blue) for the input gradation. Hereinafter, the gradation luminance table 21 will be described.

  FIG. 14 is a conceptual diagram showing an example of the gradation luminance table of the image display device 20 of the present embodiment. Generally, the contrast ratio on a display screen (monitor) such as the liquid crystal panel 22 is about 1000: 1. The contrast ratio is a ratio of the maximum luminance at the maximum gradation and the minimum luminance at the minimum gradation. In FIG. 14, the curve indicated by the broken line indicates the gradation luminance characteristics of a so-called monitor (display screen), and the gamma curve (for example, γ = 2.2) from the point where the gradation is 0 and the luminance is 0. Luminance increases with increasing gradation.

  The gradation luminance table 21 of this embodiment is provided with an LUT (lookup table) as an adjusting means, and the gradation luminance characteristics in the liquid crystal panel 22 are shown in FIG. The contrast ratio is set to about 50: 1 by correcting to a gamma curve indicated by a solid line (for example, γ = 2.2).

  The contrast ratio of the paper medium is, for example, 6-7: 1 for newspapers, 10-11: 1 for copy paper (recycled paper), 30: 1 for copy paper (ordinary white paper), and 50: 1 for printer photo paper. It is. By setting the contrast ratio to 50: 1 or less, for example, when a paper pattern representing “wrinkles” or “unevenness” of paper is used as a synthesis image (filter image), the output image is printed on a paper medium. It is possible to display in a close state. In addition, it can be set as the contrast ratio which a general printed matter usually has by setting a contrast ratio to about 30: 1. Note that the contrast ratio adjustment is not limited to a contrast ratio of 50: 1 or less. For example, the contrast ratio is close to the contrast ratio of the paper according to the target paper, such as 100: 1. Can be adjusted.

  In the example of FIG. 14, the contrast ratio is adjusted by increasing Ymin. However, the present invention is not limited to this, and the contrast (ratio between Ymax and Ymin) can be made closer to the paper. May be lowered, and Ymax may be lowered and Ymin may be raised.

  As described above, the reason for adjusting the contrast ratio in the image display device 20 is, for example, as follows. That is, even if the contrast ratio of the image is adjusted according to the contrast ratio of the paper with a personal computer (PC), the contrast ratio differs for each monitor (image display device). Cannot be displayed. In addition, a graphic board equipped in a personal computer (PC) currently processes image data with 8 bits and can only express 0 to 255 gradations. Compared with a monitor capable of expressing 0 to 1024 gradations with 10 bits, contrast adjustment in a personal computer (PC) has a large amount of gradation to be lost, and the gradation of the compressed image becomes rough. In addition, when an image whose contrast is adjusted by a personal computer (PC) is displayed on a monitor, the tone of the image is further corrected by the LUT of the monitor, so that the tone of the image is further lost.

  Next, the operation of the image generation apparatus 10 according to the present embodiment will be described. FIG. 15 is a flowchart showing a procedure of LUT control processing by the image generation apparatus 10 according to the present embodiment. The LUT control process is, for example, a process for controlling the gradation conversion process by the LUT conversion unit 15 in conjunction with the ratio during the alpha blend process. Hereinafter, for convenience, the processing subject will be described as the control unit 13.

  The control unit 13 acquires an input image (S11), and reads out a filter image set or selected by the user from the storage unit 12 (S12). The control unit 13 acquires a ratio α set (or set in advance) by the user (S13), and performs alpha blending processing to generate a composite image (S14).

  The control unit 13 calculates the gradation range (gradation width) of the composite image based on the ratio α and the gradation range (gradation width) of the filter image (S15). The control unit 13 can obtain the loss of the dynamic range of the composite image by calculating the gradation range of the composite image.

  The control unit 13 rewrites the output gradation value of the LUT conversion unit 15 in order to perform gradation expansion processing for gain correction and offset correction according to the loss of the dynamic range of the composite image (S16).

  The control unit 13 converts the gradation value of the composite image by outputting the composite image to the LUT conversion unit 15 that has been subjected to the LUT control process, and outputs an output image having a dynamic range that matches the dynamic range of the input image. Generate (S17) and end the process.

  As an example of actual use, the input image is assumed to be full scale, and once the filter image and the ratio α are set, the predetermined conditions of the LUT conversion unit 15 are determined. As long as no change is made, it is not necessary to repeat the above process.

  The image generation apparatus 10 according to the present embodiment can be realized using a general-purpose computer including a CPU, a RAM, and the like. That is, a computer program that defines each processing procedure as shown in FIG. 15 is recorded on a computer program recording medium such as a CD, a DVD, or a USB memory, and the recording medium is read into a reading device (for example, an optical disc drive). The image generation apparatus 10 can be realized on the computer by loading the computer program into a RAM provided in the computer and executing the computer program by the CPU.

  Conventionally, when a desired filter image (for example, an image representing a paper pattern) of a user is combined with an arbitrary input image (original image) by performing alpha blend processing at a ratio α, the gradation range of the combined image is { (1−α) × tone range of input image + α × tone range of filter image}. When the filter image has a pattern imitating paper, the tone range of the filter image is extremely narrow, so the tone range of the composite image is narrower than the tone range of the original input image. As the ratio α is increased, the dynamic range of the composite image is lost as the ratio α is increased. Therefore, when the image quality (saturation or contrast ratio) of the composite image is taken into consideration, there is a problem that the ratio α cannot be increased.

  As described above, in the present embodiment, the loss of the dynamic range of the composite image is calculated based on the gradation range and the ratio α of the filter image, and the parameters (output values) of the LUT conversion unit 15 are calculated by the calculated loss. Is decompressed (gain correction and offset correction), so that the dynamic range of the output image faithful to the dynamic range of the input image (original image) can be realized. In the present embodiment, even when the desired ratio α is set, the dynamic range of the output image can be made equal to the dynamic range of the input image. However, the image quality of the output image can be made comparable to the image quality of the input image, and an output image maintaining the image quality of the input image can be obtained. Since a sufficient dynamic range of an input image to the display device can be ensured, deterioration of gradation expression can be avoided as much as possible even when the display device is adjusted to a low contrast ratio of the paper medium.

  In the present embodiment, there is a display priority for at least two or more images to be subjected to alpha blend processing (for example, the display priority of the input image is higher than the display priority of the filter image). When synthesizing a high image and a low image by alpha blending processing, the LUT conversion unit 15 linked to the ratio α is set so that the final output image matches the dynamic range of an image with high display priority (for example, an input image). The tone conversion process (gradation correction process) is controlled.

  In the above-described embodiment, the dynamic range of the input image is set to full scale (for example, 0 to 255 gradations in the case of 8-bit depth image processing), and the dynamic range of the output image after passing through the LUT converter 15 (LUT) is Although the LUT control is performed so as to return to the full scale of the input image, the present invention is not limited to this. For example, when the dynamic range of the input image is not full scale, when the dynamic range changes with time, or when it is desired to arbitrarily set the dynamic range after passing through the LUT, the dynamic range or each floor is set in advance (or in real time). The LUT conversion unit 15 may be controlled by calculating a loss of the dynamic range by analyzing a histogram representing the intensity (frequency) with respect to the key level.

  The present embodiment can be applied to monochrome (gray level) and R (red) G (green) B (blue). By calculating the loss of the dynamic range for each of R (red), G (green), and B (blue) and individually performing LUT control, correction including the hue of the output image can be performed.

  When performing alpha blending processing, there may be multiple filter images (or multiple sources if the filter image is a moving image), and the amount of loss in the dynamic range of the composite image is calculated based on a specific ratio for each filter image. It is also possible to control the gradation correction processing of the LUT converter 15 by calculating.

  The LUT conversion unit 15 can also control the output stage LUT of an image output device such as a graphic card at a driver level (software), or logic by an image processing circuit such as an ASIC (Application Specific Integrated Circuit) in the video display device. It can also be controlled by level (hardware).

  In the above-described embodiment, the case where the dynamic range of the filter image is narrower than the dynamic range of the input image has been described. However, the present invention is not limited to this, and the dynamic range of the filter image is compared with the dynamic range of the input image. The present embodiment can also be applied to a case where the width is wide. In this case, when the dynamic range of the composite image becomes wider than the dynamic range of the input image, compression may be performed instead of expanding the gradation width of the composite image. Further, the control unit 13 may control the correction process by adding a positive offset to the output tone value of the LUT conversion unit 15 instead of subtracting it, or may subtract a negative offset.

  In the present embodiment, when a desired pattern image and a desired input image are combined, the combined image is not simply an image having a similar atmosphere as compared with the original image. That is, in the present embodiment, when an arbitrary input image and a desired filter image are synthesized by alpha blending processing, the dynamic range of the input image and the dynamic range of the output image are set regardless of the ratio set by the user. The output image can be obtained while maintaining the image quality of the input image regardless of how the ratio is set.

  In order to make the image quality of the composite image the same as that of the original image, the LUT conversion for gradation correction is performed a plurality of times (for example, twice) so that the image quality of the composite image is the same as that of the original image. It is also conceivable if you can. However, in this embodiment, an output image that maintains the image quality of the input image can be obtained by rewriting the output value of the LUT converter 15 only once according to the calculated loss of the dynamic range.

(Embodiment 2)
FIG. 16 is a block diagram illustrating an example of the configuration of the image display device 30 according to the second embodiment. As illustrated in FIG. 16, the image display device 30 includes a storage unit 32 that stores the input image and the filter image 121, a control unit 33 that controls the image display device 30, and a composite image generation unit that combines the input image and the filter image. A composite image generation unit 34, a LUT (look-up table) conversion unit 35 as gradation correction means, an operation unit 36 for a user to set a ratio (also referred to as transmittance), a gradation luminance table 37, A liquid crystal panel 38 and the like are provided.

  Note that the storage unit 32, the control unit 33, the composite image generation unit 34, the LUT conversion unit 35, the operation unit 36, the gradation luminance table 37, and the liquid crystal panel 38 are the storage unit 12, the control unit 13, and the liquid crystal panel 38 of the first embodiment, respectively. Since it is equivalent to the composite image generation unit 14, the LUT conversion unit 15, the operation unit 16, the gradation luminance table 21, and the liquid crystal panel 22, the description thereof is omitted.

  The control unit 33 includes a gradation range calculation unit 331 as a calculation unit that calculates a gradation value width, a gain calculation unit 332 as a ratio calculation unit, an offset calculation unit 333 as an offset calculation unit, and the like.

  Note that the gradation range calculation unit 331, the gain calculation unit 332, and the offset calculation unit 333 are equivalent to the gradation range calculation unit 131, the gain calculation unit 132, and the offset calculation unit 133 according to Embodiment 1, respectively. Omitted.

  According to the second embodiment, it is possible to realize an image display device that exhibits the same effect as described in the first embodiment. Examples of the image display device include a video display device, a mobile phone, a tablet PC, and a mobile device having a display screen.

(Embodiment 3)
FIG. 17 is a block diagram illustrating an example of the configuration of the image generation apparatus 40 according to the third embodiment. The difference from the image generation apparatus 10 according to the first embodiment is that a contrast adjustment unit 17 is provided.

  The contrast adjustment unit 17 has the same function as the LUT of the gradation luminance table 21 of the first embodiment. That is, the contrast adjustment unit 17 adjusts the contrast ratio on the monitor by correcting the output gradation of the LUT conversion unit 15 so as to increase the luminance of gradation 0 in an image display device such as a monitor.

  The contrast ratio of the paper medium is, for example, 6-7: 1 for newspapers, 10-11: 1 for copy paper (recycled paper), 30: 1 for copy paper (ordinary white paper), and 50: 1 for printer photo paper. It is. By adjusting the contrast ratio, for example, when a paper pattern representing paper “wrinkles” or “unevenness” is used as the filter image, the output image can be displayed in a state close to a paper medium. Become. In addition, it can be set as the contrast ratio which a general printed matter usually has by setting a contrast ratio to about 30: 1.

10, 40 Image generation device 20, 30 Image display device 13, 33 Control unit 131, 331 Tone range calculation unit 132, 332 Gain calculation unit 133, 333 Offset calculation unit 14, 34 Composite image generation unit 15, 35 LUT conversion unit 16, 36 Operation unit 17 Contrast adjustment unit 21, 37 Gradation luminance table

Claims (9)

Any second image each gradation value having the first image and the first image is different from the second gradation range in a first tone width including gradation value by superimposing in any ratio to generate a composite image A composite image generating means ;
Gradation conversion means for converting the gradation value of the composite image generated by the composite image generation means under a predetermined condition;
An image generation apparatus comprising: condition changing means for changing the predetermined condition so as to compensate for a loss gradation width from the first gradation width that is generated as a result of generating a composite image by the composite image generation means . Comprising a calculating means for calculating a gradation width of the composite image based on the second tone width before Symbol ratio and the second image,
The condition changing means includes
The image generation apparatus according to claim 1, wherein the predetermined condition is changed based on a gradation value calculated by the calculation unit. The condition changing means includes
2. The predetermined condition is changed to extend or compress the gradation width of the composite image so that the gradation width of the composite image becomes the gradation width of the first image. Or the image generation apparatus of Claim 2. The gradation converting means includes
A lookup table for converting input tone values to output tone values;
The condition changing means includes
The image generating apparatus according to claim 1, wherein the predetermined condition is changed by rewriting an output gradation value of the lookup table.   5. The image generation according to claim 1, further comprising an adjustment unit configured to adjust a contrast ratio of an output image obtained by converting a gradation value by the gradation conversion unit. apparatus. An image generation system comprising: the image generation device according to any one of claims 1 to 4; and an image display device that displays an output image obtained by converting a gradation value by the image generation device. ,
The image display device includes:
An image generation system comprising adjustment means for adjusting a contrast ratio of the output image. A composite image is generated by superimposing gradation values of a first image having a first gradation width including an arbitrary gradation value and a second image having a second gradation width different from the first image at an arbitrary ratio. A composite image generating means;
Gradation conversion means for converting the gradation value of the composite image generated by the composite image generation means under a predetermined condition;
Condition changing means for changing the predetermined condition so as to compensate for the loss gradation width from the first gradation width generated as a result of generating the composite image by the composite image generation means ;
An image display apparatus comprising: an adjusting unit that adjusts a contrast ratio of an output image whose tone value is converted by the tone converting unit. On the computer,
Any second image each gradation value having the first image and the first image is different from the second gradation range in a first tone width including gradation value by superimposing in any ratio to generate a composite image Steps,
Converting the gradation value of the generated composite image under a predetermined condition;
And a step of changing the predetermined condition to compensate for a lossy gradation width from the first gradation width generated as a result of generating the composite image . Any second image each gradation value having the first image and the first image is different from the second gradation range in a first tone width including gradation value by superimposing in any ratio to generate a composite image Steps,
Converting the gradation value of the generated composite image under a predetermined condition;
Changing the predetermined condition so as to compensate for the lossy gradation width from the first gradation width generated as a result of generating the composite image .

Images