JP2007042033A - Color correction apparatus and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color correction apparatus for suppressing abrupt changes in color, and correcting the color of an image to be more preferable. <P>SOLUTION: A color-weighting calculating part 3 calculates a color weighting signal 301 that, gradually decreases from the predetermined color region to outside the color region. The first coordinate movement calculating part 4 calculates a first coordinate movement for keeping the color coordinate values of the image data close to the color coordinate values of the specific color, based on the movement corresponding to the preset color coordinate values. Next, the second coordinate movement calculating part 8 calculates a second coordinate movement by multiplying the color weighting signal 301 with the first color coordinate movement. A coordinate-moving part 9 moves the color coordinate values, by adding the second coordinate movement to the color coordinate values of the image data. As a result, abrupt change in color is suppressed, and an inputted image data can be corrected to the specific colored image data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a color correction apparatus and an image display apparatus, and more particularly to a color correction apparatus and an image display apparatus that can correct the color of an image more preferably.

  In a color correction apparatus and an image display apparatus mounted on a conventional color television or the like, a color error due to display device characteristics is corrected and color reproduction is performed so as to be as faithful as possible to the original image.

  On the other hand, humans are sensitive to specific colors. For example, sky color, human face color, plant color, cherry blossom color, flower color, soil color, vegetable color, etc. are said to be reminiscent colors that can be associated with the real thing, memory colors is called. Among them, it is said that it is particularly sensitive to the skin color of human skin, the sky sky color of landscapes, and the green color of plants. In general, it is known that a memory color is different from an actual color because its characteristics are emphasized and stored more vividly than an actual color. Therefore, it is said that it is more preferable for human beings to reproduce colors close to memory colors than to reproduce faithful colors.

  Since this memory color varies depending on the country, region, age, etc., data on the country, region, and age that the device is to be used for is collected, and the data obtained from the subjective evaluation is statistically processed and determined in advance. . Normally, memory colors are distributed in a certain color area, and color correction is performed using the representative colors as target colors.

  In this specification, the “specific color” is a representative color of a color region that is individually determined in advance, such as a memory color, and is a target color.

  In general, in the memory color correction, a color close to the memory color included in the image is corrected so as to be closer to the memory color. Therefore, in order to suppress the influence on colors other than the memory color, a color area close to the memory color is extracted and only the area is corrected. For example, in the landscape image in the image, the color of the blue sky region in the landscape is corrected to the sky blue of the memory color and output.

  However, when a memory color area is extracted and local correction is performed only on that area, the color change from the area that has not been corrected becomes abrupt and a pseudo contour is generated at the boundary. was there.

  To avoid this problem, calculate the statistic of the memory color area included in the entire image, determine what the main subject is, and define the image as a “portrait image”, “landscape image”, “small person image” And a method of switching color correction for each category has been developed.

  Specifically, for a “portrait image” in which a person appears in a relatively wide range, only the memory color area (for example, the person's skin area) is extracted, and only the brightness of the person's skin color area is corrected. In this case, the difference in brightness between the skin color area and the surrounding area becomes abrupt, and the pseudo contour is conspicuous.

Therefore, an area that approximates a predetermined memory color, such as a human skin area (skin color area), a landscape sky area (sky blue area), a green area of green grass (green area) (hereinafter simply referred to as “memory color area”). ")" In the entire image is calculated and classified into categories. Next, depending on the category, whether or not to perform memory color correction on a local area is determined and the process is switched, thereby suppressing the occurrence of pseudo contours (for example, Patent Document 1).
JP 2003-216951 A

  However, in the above-described conventional configuration, when memory color correction is performed, a color change occurs near the boundary between the memory color area and the memory color area. Further, this change is conspicuous in moving images. Further, in memory color correction, in order to further improve the correction effect, there is a problem that the amount of correction is increased so as to be closer to the memory color as the distance from the memory color increases, and a rapid color change is likely to occur near the boundary of the region.

  An object of the present invention is to provide a color correction apparatus and an image display apparatus for suppressing an abrupt color change and more preferably correcting an image color.

  In order to achieve the above object, the color correction apparatus according to the present invention includes a first coordinate for moving the color coordinate value of the input image data based on a coordinate movement amount set in advance corresponding to the color coordinate value. A first coordinate movement amount calculation unit that calculates a movement amount, and a color weight calculation unit that calculates a color weight according to a color coordinate value based on a weight function that decreases from a predetermined color region toward the outside of the color region A second coordinate movement amount calculation unit that calculates a second coordinate movement amount by multiplying the first coordinate movement amount by a color weight, and a coordinate movement unit that moves a color coordinate value based on the second coordinate movement amount It is characterized by comprising.

  With such a configuration, it is possible to suppress a rapid color change near a boundary between a predetermined color area and the color area, and to move a color coordinate value in the image.

  Further, there may be a plurality of predetermined color regions, and the color weight calculation unit may be configured to calculate weights for each color region.

  With such a configuration, a weight can be calculated for each predetermined color area, and an optimum weight can be calculated for each color area.

  Further, the color coordinate value may be specified from a hue value, a saturation value, and a brightness value.

  With such a configuration, the hue value, saturation value, and brightness value can be processed independently.

  Further, the coordinate moving unit may be configured to move the color coordinate value by adding the color coordinate value and the second coordinate movement amount.

  With such a configuration, the color coordinate value can be moved while suppressing the circuit scale.

  Moreover, the structure provided with the memory | storage part which enabled the setting of the offset value which changes the hue value of the input image data may be sufficient.

  With such a configuration, the detection range of a predetermined color area can be changed, and the color coordinate value can be moved in accordance with the color characteristics of the image.

  The color correction apparatus further detects an image memory that stores image data in units of frames or fields, and a color component detection unit that detects a color component of a predetermined condition from the image data stored in the image memory. Among the color components, a configuration is provided that includes an offset calculation unit that creates a hue component histogram and calculates an offset value based on the distribution of the histogram, and a setting unit that sets the calculated offset value in a storage unit. Also good.

  With such a configuration, it is possible to make an abrupt color change near a predetermined color region and a boundary outside the color region less noticeable.

  Moreover, it is preferable that the color component of the predetermined condition is a color component in a predetermined saturation region and in a predetermined lightness region.

  With such a configuration, it is possible to detect color components within a predetermined saturation region and within a predetermined lightness region, and it is possible to detect only color components closer to a specific color.

  Further, the offset value may be determined based on the set color temperature.

  With such a configuration, the detection range of the color area can be changed according to the set color temperature, and the color coordinate value can be moved according to the feature of the image.

  The image display device of the present invention includes a data receiving unit that receives image data transmitted or broadcasted, a color correction device that moves a color coordinate value of the received image data, and a color moved by the color correction device. And a display unit for displaying image data of coordinate values.

  With such a configuration, an image display apparatus that can suppress a rapid color change near a boundary between a predetermined color area and the outside of the color area and move a color coordinate value in the image can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the color correction apparatus and image display apparatus for suppressing the rapid color change and correcting the color of an image more preferably can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
First, the color correction apparatus according to the first embodiment will be described. FIG. 1 is a block diagram of a color correction apparatus 1 according to the first embodiment.

  In FIG. 1, a color space conversion unit 5 converts image data (Ri, Gi, Bi) of RGB color coordinates specified by Ri (red), Gi (green), and Bi (blue) into hue, saturation, and brightness. Is converted into image data (H, S, V) of the HSV color coordinates specified in. Here, H is the hue, S is the saturation, and V is the lightness, and the hue data 101, the saturation data 102, and the lightness data 103 are output. Details of the conversion will be described later.

  Next, the color area determination unit 2 detects a predetermined color area from the hue data 101 and outputs a determination signal 202. For example, color regions such as a skin color region of a person's face, a sky sky region of a landscape image, and a green region of plants are determined in advance, and the color region is determined. Also, hue change data 203 for changing the detected hue is output. Details of the hue change data 203 will be described later.

  Next, the color weight calculation unit 3 inputs the determination signal 202 and the hue change data 203, and inputs the input image data based on weight functions set in advance for each of the hue axis, the saturation axis, and the brightness axis. A weight corresponding to the color coordinate value is calculated, and a color weight signal 301 (Kg) is output. The color weight signal 301 (Kg) is a weight signal for changing the amount of movement for moving the color coordinate value.

  Next, the first coordinate movement amount calculation unit 4 inputs the determination signal 202, the hue change data 203, and the color weight signal 301, and a specific color predetermined for the hue data 101, saturation data 102, and lightness data 103. In order to approximate the color coordinate value, the movement direction and size are determined, the first coordinate movement amount is calculated, and the movement amount δh, the movement amount δs, and the movement amount δv are output.

  Here, the specific color is, for example, a color determined in advance by experimentally obtaining a representative color that is stored as an impression by human beings. For example, it is a representative color that is determined by collecting data of representative colors of human skin, representative colors of the sky in landscapes, and representative colors of greenery of plants and statistically processing subjective evaluation data. It is.

  Next, the second coordinate movement amount calculation unit 8 inputs the color weight signal 301 (Kg) and the first coordinate movement amount, that is, the movement amount δh, the movement amount δs, and the movement amount δv. A second coordinate movement amount for approximating the color coordinate value of a specific color determined in advance with respect to the degree data 102 and the lightness data 103 is calculated, and a hue movement amount 401 (Δh), a saturation movement amount 402 (Δs), The brightness shift amount 403 (Δv) is output.

  Next, the coordinate moving unit 9 stores the hue movement amount 401 (Δh), the saturation movement amount 402 (Δs), the lightness movement amount 403 (Δv), the hue data 101, the saturation data 102, and the lightness data 103, respectively. Addition processing is performed, and the color coordinate value of the input image data is moved so as to approach the color coordinate value of a specific color.

  Specifically, the adder 11 adds the hue data 101 and the hue shift amount 401 (Δh), the adder 12 adds the saturation data 102 and the saturation shift amount 402 (Δs), and the adder 13 sets the brightness. Data 103 and brightness shift amount 403 (Δv) are added.

  Here, the color changes as the color coordinate value moves. Therefore, the greater the amount of movement, the greater the color change. Therefore, moving so as to approach the color coordinate value of a specific color is the same as performing color correction so as to approach the specific color.

  Next, the color space inverse transform unit 6 inversely transforms the image data (H, S, V) designated by the HSV color coordinates into image data (Ro, Go, Bo) designated by the RGB color coordinates, and outputs them. To do. Details of the inverse transformation will be described later.

  Next, the color correction apparatus 1 in the first embodiment will be described in more detail.

  First, the color area determination unit 2 will be described with reference to FIGS. FIG. 2 is a block diagram of the color area determination unit 2, and FIG. 3 is an explanatory diagram of the color selection unit 21. In FIG. 2, a color selection unit 21 predetermines color areas such as a skin color area of a person's face, a sky sky area of a landscape image, and a green area of plants, and a skin color area, a sky color area, a green area, and the like from the hue data 101. And the determination signal 202 is output. As shown in FIG. 3, the determination signal 202 is set for the hue. Here, for example, 0 ≦ θ <60 in the hue phase is a skin color region, and “0” is assigned as the determination signal 202. Similarly, as the assignment of the determination signal 202, 60 ≦ θ <180 is assigned a green region “1”, 180 ≦ θ <300 is assigned a sky blue region, “2” is assigned, and 300 ≦ θ <360 is assigned a skin color region. Assign “0”.

  Note that the color selection unit 21 inputs the hue data 101 as it is to detect the color area at an arbitrary angle of the hue, but may detect a fixed angle as a unit. For example, the hue may be divided into 12 regions in units of 30 degrees. In this case, only the upper 4 bits of the hue data 101 need be detected.

  Next, the case where the range of the color area to be detected is changed will be described. The phase changing unit 22 selects the outputs of the register 24, the register 25, and the register 26 in accordance with the determination signal 202, and outputs the hue offset value set in each register. Thereby, the color detection range for each color region can be changed independently. For example, an offset value for the skin color region is set in the register 24 and a signal 241 is output. Similarly, an offset value for the green region is set in the register 25 and a signal 242 is output. An offset value for the sky blue area is set in the register 26 and a signal 243 is output. The phase changing unit 22 selects an output from each register according to the determination signal 202 and outputs changed data 244. Further, the adder 23 outputs hue change data 203 obtained by subtracting the change data 244 of the phase change unit 22 from the hue data 101.

  The number of bits required for the register is determined by the hue detection range and resolution. For example, when detecting from 0 to 127 in units of 1 step, 7 bits are required. In this case, the upper bits of the register are sign bits and determine the color direction in which the hue is shifted.

  The hue change data 203 uses lower L bits (N> L) when the data accuracy of the hue data 101 is expressed with a resolution of N bits. The required number of bits is determined by the hue detection range and resolution. For example, when detecting from 0 to 255 in units of one step, 8 bits are required.

  Next, the color weight calculation unit 3 will be described with reference to FIGS. 4, 5, and 6. Based on the weight Kh along the hue axis, the weight Ks along the saturation axis, and the weight Kv along the lightness axis, the color weight calculation unit 3 determines the amount of movement corresponding to the color coordinate value. The color weight signal 301 (Kg) to be changed is output.

  First, in FIG. 4, the hue weight calculation unit 31 is based on a weight function that is determined in advance based on a weight function that determines how much the hue axis is processed according to the degree of approximation with a specific color. The weight Kh for changing the size of the image data is calculated corresponding to the hue of the image data.

  Specifically, with respect to the hue axis, as shown in FIG. 5A, the weight Kh outputs the maximum value “1” at the center Ps of the flesh color region, and the lower limit P1 and the upper limit away from Ps. The minimum value “0” is output at a certain P3. Here, the vertical axis represents the weight Kh, and the horizontal axis represents the hue. The hue value varies from 0 to 360 degrees.

  Similarly, as shown in FIG. 5D, the weight Kh outputs the maximum value “1” at the center Pb of the sky blue region, and the minimum value “0” at the lower limit P6 and the upper limit P9. Is output. Here, the vertical axis represents the weight Kh, and the horizontal axis represents the hue. Here, the vertical axis represents the weight Kh, and the horizontal axis represents the hue. The hue value varies from 0 to 360 degrees.

  Further, as shown in FIG. 5G, the weight Kh outputs the maximum value “1” at the center Pg of the green region, and the minimum value “0” is set between the lower limit value P3 and the upper limit value P6 that are separated from Pg. Output. Here, the vertical axis represents the weight Kh, and the horizontal axis represents the hue. The hue value varies from 0 to 360 degrees.

  That is, the hue is maximized at hues Ps, Pb, and Pg that match a predetermined specific color, and decreases with distance from Ps, Pb, and Pg. Since Ps, Pb, and Pg differ depending on the country, region, age, and the like, data such as the country, region, age, etc., to which the apparatus is to be used is collected, subject evaluation data is statistically processed, and a target color is determined in advance.

  In addition, according to the determination signal 202, it is determined which specific color region the weight Kh is to be output. For example, if the determination signal 202 is “0”, the skin color area weight Kh is output. Similarly, if the determination signal 202 is “1”, the green region weight Kh is output, and if the determination signal 202 is “2”, the light blue region weight Kh is output.

  Here, the operation of the hue weight calculation unit 31 will be described with reference to FIG. In FIG. 6, the weighting function is set so as to continuously decrease from a predetermined color area toward the outside of the color area. For example, the predetermined color area is an area based on the memory color area, and P1 to P2 are normally set as the skin color area. However, in the present invention, the weight change range is expanded from P1 to P9 for the lower limit value and from P2 to P3 for the upper limit value. Therefore, the weight Kh is set to the maximum value “1” for the skin color Ps and decreases on the lower limit P9 side and the upper limit P3 side.

  Similarly, the normally set green region is P4 to P5, but the lower limit value of the hue of the green region is expanded from P4 to P3, and the upper limit value is expanded from P5 to P6. The weight Kh is green Pg and has a maximum value “1”, and decreases on the lower limit P3 side and the upper limit P6 side.

  Further, the hue range of the normally set sky blue area is P7 to P8, but the lower limit value of the sky blue area is increased from P7 to P6, the upper limit value is increased from P8 to P9, the weight Kh is the maximum value “ 1 ”, and decreases on the P6 side of the lower limit value and the P9 side of the upper limit value.

  As described above, the weight Kh is set so as to continuously decrease from a predetermined color area toward the outside of the color area, and therefore, a binary change with correction to a specific color and without correction. Disappears. Further, the change in the weight Kh can be made gentle by expanding the change range of the weight on the hue axis. Therefore, it is possible to suppress a rapid color change near the boundary between the predetermined color area and the outside of the color area.

  Next, the saturation weight calculation unit 32 calculates a weight Ks for changing the amount of movement with respect to the saturation axis for each specific color corresponding to the saturation of the color coordinate value of the image data. To do. Specifically, the weight Ks is determined as shown in FIGS. 5B, 5E, and 5H. Here, the vertical axis represents the weight Ks, and the horizontal axis represents the saturation. The value of saturation changes from 0 to 255.

  Further, in accordance with the determination signal 202, it is determined which specific color region to output the weight. For example, if the determination signal 202 is “0”, the skin color area weight Ks is output. Similarly, if the determination signal 202 is “1”, the green region weight Ks is output, and if the determination signal 202 is “2”, the light blue region weight Ks is output.

  Next, the lightness weight calculation unit 33 calculates, for each specific color, a weight Kv for changing the amount of movement with respect to the lightness axis, corresponding to the lightness of the color coordinate value of the image data. Specifically, the weight Kv is determined as shown in FIGS. 5C, 5F, and 5I. Here, the vertical axis represents the weight Kv, and the horizontal axis represents the lightness. The brightness changes from 0 to 255.

  Further, in accordance with the determination signal 202, it is determined which specific color region to output the weight. For example, if the determination signal 202 is “0”, the skin color region weight Kv is output. Similarly, if the determination signal 202 is “1”, the green region weight Kv is output, and if the determination signal 202 is “2”, the light blue region weight Kv is output.

  The weights Kh, weights Ks, and weights Kv determined as described above are multiplied by the multiplier 34 and the multiplier 35, respectively, and the color weight signal 301 (Kg) that changes the magnitude of the movement amount of the color coordinate value is obtained. Is calculated by the following equation.

  The color weight signal 301 (Kg) may be the minimum value of the weight Kh, the weight Ks, and the weight Kv, and the amount of movement can be changed similarly. As a result, multipliers having a large circuit scale can be reduced, and the hardware circuit scale can be reduced.

  In this way, the color weight signal 301 (Kg) is determined based on the weight Kh along the hue axis, the weight Ks along the saturation axis, and the weight Kv along the lightness axis.

  The degree of decrease of the weight Kh, the weight Ks, and the weight Kv on the hue axis, the saturation axis, and the brightness axis may be constant or may be a non-linear change in weight approximated by an nth-order curve. May be.

  The hue weight calculation unit 31, the saturation weight calculation unit 32, and the lightness weight calculation unit 33 may be configured by hardware logic or a lookup table (hereinafter referred to as “LUT”). Also good. By configuring with an LUT, complex weights can be created in advance and can be provided in a read-only memory (hereinafter referred to as “ROM”). In order to update the weight, a rewritable memory such as a random access memory (hereinafter referred to as “RAM”) may be used.

  Next, the first coordinate movement amount calculation unit 4 will be described with reference to FIGS. 4 and 7.

  In FIG. 4, a hue movement amount calculation unit 41 calculates a movement amount δh so that the hue of the color coordinate value of the input image data approaches each specific color. Specifically, as shown in FIG. 7A, the movement amount δh is calculated so that the color coordinate value of the flesh color region approaches Ps on the hue axis. Here, if the signs are different, the moving direction is opposite. Similarly, as shown in FIG. 7D, the movement amount δh is calculated so that the color coordinate value of the sky blue region approaches Pb. Further, as shown in FIG. 7G, the movement amount δh is calculated so that the color coordinate value of the green region approaches Pg.

  Here, the vertical axis represents the movement amount δh, and the horizontal axis represents the hue. The hue value varies from 0 to 360 degrees.

  Note that the movement amount was calculated so as to approach the specific colors of Ps for the flesh-color area, Pb for the sky-color area, and Pg for the green-color area, but for example, the hue of the entire sky-blue area is unidirectional to make the sky blue appear more blue. The amount of movement that rotates may be calculated, or the amount of movement that rotates the hue of the entire green region in one direction may be calculated in order to enhance the green impression of plants. In both cases, it is possible to reproduce a hue closer to a human impression.

  Further, which specific color the movement amount δh is output to is determined according to the determination signal 202. For example, if the determination signal 202 is “0”, the movement amount δh of the skin color region is output. Similarly, if the determination signal 202 is “1”, the movement amount δh of the green region is output, and if the determination signal 202 is “2”, the movement amount δh of the sky blue region is output.

  Further, the movement amount is increased as the hue is separated from the skin color Ps, sky blue Pb, and green Pg. For this reason, the amount of movement is increased so that the color farther from the specific color approaches the specific color, and the effect of color correction is made stronger. As a result, color reproduction that is more favorable for human beings is realized.

  Next, the saturation movement amount calculation unit 42 calculates a movement amount δs with respect to the saturation axis for each specific color region. Specifically, as shown in FIGS. 7B, 7E, and 7H, the movement amount δs is determined. Here, the vertical axis represents the movement amount δs, and the horizontal axis represents the saturation. The value of saturation changes from 0 to 255.

  Further, which specific color the movement amount δs is output is determined according to the determination signal 202. For example, if the determination signal 202 is “0”, the movement amount δs of the skin color region is output. Similarly, if the determination signal 202 is “1”, the movement amount δs of the green region is output, and if the determination signal 202 is “2”, the movement amount δs of the sky blue region is output.

  Next, the lightness movement amount calculation unit 43 calculates a movement amount δv with respect to the lightness axis for each specific color region. Specifically, the movement amount δv is determined as shown in FIGS. 7C, 7F, and 7I. Here, the vertical axis represents the movement amount δv, and the horizontal axis represents the brightness. The brightness changes from 0 to 255.

  Further, which specific color the movement amount δv is output is determined according to the determination signal 202. For example, if the determination signal 202 is “0”, the movement amount δv of the skin color region is output. Similarly, if the determination signal 202 is “1”, the movement amount δv of the green region is output, and if the determination signal 202 is “2”, the movement amount δv of the sky blue region is output.

  As described above, the first coordinate movement amount calculation unit 4 performs the first coordinate movement for moving the color coordinate value set in advance according to the hue, saturation, and brightness of the input image data. A movement amount δh, a movement amount δs, and a movement amount δv, which are amounts, are output.

  Next, the second coordinate movement amount calculation unit 8 uses the multipliers 44 to 46 to multiply the input movement amounts δh, movement amounts δs, and movement amounts δv by the color weight signal 301 (Kg), respectively. A hue movement amount 401 (Δh), a saturation movement amount 402 (Δs), and a lightness movement amount 403 (Δv), which are coordinate movement amounts, are output. In this way, the magnitude of the movement of the color coordinate value can be changed by the color weight signal 301. That is, the effect and strength of color correction can be changed. As a result, even if the color correction is continuously performed from the predetermined color area to the outside of the color area, the movement amount of the color coordinate value is gently and sufficiently reduced outside the predetermined color area. The influence of the color correction on the color outside the predetermined color area in the image can be suppressed.

  Therefore, it is possible to eliminate binary processing switching with or without correction to a specific color in the vicinity of the boundary outside the color area from a predetermined color area, and abrupt color change can be suppressed. .

  The hue movement amount calculation unit 41, the saturation movement amount calculation unit 42, and the lightness movement amount calculation unit 43 may be configured by hardware logic or an LUT. By configuring with the LUT, a complicated movement amount can be created in advance, and can be provided in a ROM or the like.

  Moreover, in order to be able to update the magnitude | size of movement amount, you may comprise by rewritable memory, for example, RAM.

  Since the first coordinate movement amount of the first coordinate movement amount calculation unit 4 is weighted by the color weight signal 301, the movement direction of the color coordinate value and the magnitude of the movement amount can be set independently. Individual functions can be approximated with simple functions. Therefore, the circuit can be simplified.

  Further, the operations of the color weight calculation unit 3, the first coordinate movement amount calculation unit 4 and the second coordinate movement amount calculation unit 8 are processed in advance, image data (H, S, V) is input, and output data (Δh, You may comprise by one LUT which outputs (DELTA) s and (DELTA) v). Thereby, complicated calculations can be performed in advance and the speed can be increased.

  Next, the coordinate moving unit 9 adds the hue movement amount 401 (Δh), the saturation movement amount 402 (Δs), the lightness movement amount (Δv), and the hue data 101, saturation data 102, and lightness data 103, respectively. Then, the color coordinate value of the input image data is moved to the color coordinate value of the specific color.

  Specifically, the adder 11 adds the hue data 101 and the hue shift amount 401 (Δh), the adder 12 adds the saturation data 102 and the saturation shift amount 402 (Δs), and the adder 13 sets the brightness. Data 103 and brightness shift amount 403 (Δv) are added.

  As a result, the input image data (H, S, V) is converted into corrected image data (H ′, S ′, V ′). The conversion is expressed by the following three expressions.

  Here, δh, δs, and δv are first coordinate movement amounts, Kg is a color weight, and Δh, Δs, and Δv are second coordinate movement amounts.

  Next, the color space inverse transform unit 6 inversely transforms the image data designated by the HSV color coordinates into image data designated by the RGB color coordinates. Thereby, image data (Ro, Go, Bo) is output.

  As described above, according to the first embodiment, the amount of movement increases as the hue moves away from the skin color Ps, green Pg, and sky blue Pb. For this reason, as the color is farther from the specific color, the color is moved closer to the specific color, so that the effect of color correction becomes stronger. As a result, color reproduction that is more favorable for human beings is realized.

  Further, the color weight signal 301 (Kg) for changing the magnitude of the movement amount is set so as to continuously decrease from a predetermined color area toward the outside of the color area based on a preset weight function. Yes. As a result, it is possible to eliminate binary processing switching with or without correction to a specific color near the boundary, and abrupt color change near the boundary can be suppressed.

  Further, since the change of the weight function is gradually and decreasing from the predetermined color area toward the outside of the color area, the influence on the color other than the predetermined color area in the image is suppressed. .

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. Hereinafter, in order to avoid duplication about the point similar to 1st Embodiment, description is abbreviate | omitted.

  The second embodiment is different from the first embodiment in that an offset value 701 used for changing the hue is obtained from the color region determination unit 2 using the image analysis unit 7.

  In FIG. 8, the image analysis unit 7 detects a hue data 101 within a predetermined saturation area and within a predetermined brightness area from the image data (H, S, V), and detected hue data 101. A frame memory that records the color, a histogram creation unit that creates a histogram of the recorded hue data, and a distribution amount in the vicinity of the boundary between the predetermined color area and the outside of the color area is detected from the distribution of the created histogram, The offset value is calculated so as to reduce the distribution amount, and the setting unit sets offset values 701 (ΔX1, ΔX2, ΔX3) in the registers 24, 25, and 26. With this configuration, a rapid color change that tends to occur near the boundary due to the movement of the color coordinate value is suppressed.

  Note that the frame memory may be a field memory by analyzing an image in units of fields instead of in units of frames. That is, it is only necessary to secure a predetermined image area.

  As another function, when the color correction device 10 is incorporated in a digital television including a display unit such as a CRT, a plasma display panel, or a liquid crystal panel, the image analysis unit 7 is based on a color temperature set from the outside. Change the target value for moving the color coordinate values. For example, when the color temperature is set high by the operation button, the color displayed on the digital television shifts in the blue direction. Therefore, the offset value 701 (ΔX1, ΔX2, ΔX3) is increased.

  As a result, the target color can be moved in the blue direction in accordance with the color temperature. For example, the color area determination unit 2 receives the offset value 701 and shifts the detection center of the sky blue area in the blue direction by the offset value (ΔX3) as shown in FIG. Similarly, the center of detection of the skin color region and the green region can be shifted in the blue direction by the offset value ΔX1 and the offset value ΔX2.

  Each offset value may be the same or different. In order to independently adjust the colors, ΔX1, ΔX2, and ΔX3 may be set in the registers 24, 25, and 26 shown in FIG.

  As a result, the target value can also be changed based on the color temperature, and color reproduction optimal for the color temperature can be realized.

  Further, the offset value may be adjusted when it is determined that the color balance is shifted by detecting the white balance of the photographing data of a digital camera or the like.

  As a result, it is possible to correct color deviation due to the influence of external light such as sunset and illumination light.

  Next, the color space conversion unit 5 and the color space inverse conversion unit 6 shown in FIG. 1 will be described in detail with reference to FIGS.

  The image data is often image data represented by RGB color coordinates as shown in FIG. 11 as a display device signal that emits light from Red (R), Green (G), and Blue (B).

  Therefore, the image data expressed by RGB color coordinates is converted into image data expressed by HSV color coordinates. The HSV coordinate system is exactly a cylindrical coordinate system, but as shown in FIG. 12, the color space is often represented by a hexagonal pyramid having RGBCMY as its apex. H is a hue, and is represented by 0 to 360 degrees counterclockwise with the direction of R being “0”. S is the saturation indicating the vividness, and the center line portion is “0” and increases as it goes in the circumferential direction. V is lightness indicating brightness. The apex of the pyramid is black, and the center of the bottom surface (upper hexagon in FIG. 12) is white.

  In the color space conversion unit 5, conversion from image data specified by RGB color coordinates to image data specified by HSV color coordinates is performed by the following three expressions. However, 0 ≦ R, G, B ≦ MAX, 0 ≦ S, V ≦ MAX, 0 ≦ V ≦ 360, and n are the number of bits of image data expressed by input RGB color coordinates.

  The inverse transformation formula of the color space inverse transformation unit 6 is as follows.

  In general, the definition threshold of the RGB color space is equal to the definition threshold of the HSV color space, and if the correction is within the definition threshold, one-to-one mapping can be performed.

  On the other hand, a color space that is neither RGB nor HSV, for example, the YCbCr color space, exceeds the RGB definition threshold in a high-saturation region, and the color may be clipped if it is returned to the RGB space after correction. Therefore, when the YCbCr color space is used, detection may be performed so as not to exceed the RGB definition threshold.

  As described above, according to the second embodiment, the image analysis unit 7 is within a predetermined saturation region from the image data (H, S, V) recorded in the memory in units of frames or fields, and Hue data 101 in a predetermined brightness area is detected, and a histogram of the hue data is created. For example, the lightness region is 50 to 255, and the saturation region is 50 to 255. Then, a distribution amount in the vicinity of the boundary between the predetermined color region and the outside of the color region is detected from the distribution, an offset value is calculated so that the distribution amount in the vicinity of the boundary becomes small, and the register 24, the register 25, and the register 26 are stored. Offset values 701 (ΔX1, ΔX2, ΔX3) are set. With this configuration, it is possible to suppress a rapid color change that is likely to occur near the boundary due to color correction.

  Further, the color correction device 1 or the color correction device 10 may be incorporated in a digital television including a display unit such as a CRT, a plasma display panel, or a liquid crystal panel. In digital television, a data receiving unit that receives image data transmitted or broadcasted, and the color coordinate value of the received image data are moved by the color correction device 1 or the color correction device 10, and the image of the moved color coordinate value is obtained. Display the data on the display.

  As a result, a rapid color change near a predetermined color region and a boundary other than the color region can be suppressed, and color correction more preferable for human beings can be realized. Further, by incorporating the color correction device 10 into the digital television, the image analysis unit 7 changes the offset value 701 based on the color temperature set from the outside, and changes the target value for moving the color coordinate value. Thereby, more preferable color reproduction can be realized.

  Further, the color correction device 1 or the color correction device 10 of the present invention is incorporated in an image output device such as a portable terminal, an information processing device, a digital still camera, or a printer instead of a digital television, and color correction is performed. Similarly, more preferable color reproduction can be realized.

  The series of processes of the color correction device 1 and the color correction device 10 described above may be executed by hardware such as an integrated circuit, or may be executed by software such as a CPU or DSP. When executed by software, an apparatus that executes the software is configured by a computer as shown in FIG. 13, for example.

  In FIG. 13, the CPU 81 executes various processes according to a program stored in the ROM 82 or a program loaded from the recording unit 86 to the RAM 83. The RAM 83 also appropriately stores data necessary for the CPU 81 to execute various processes.

  The CPU 81, ROM 82, and RAM 83 are connected to each other via a bus 91. The bus 91 includes an input unit 84 such as a keyboard and a mouse, an output unit 85 including a display such as a CRT, a plasma display panel, and a liquid crystal panel, a storage unit 86 including a hard disk, a modem, a terminal adapter, and the like. The communication unit 87 to be connected is connected. The communication unit 87 performs communication processing via a network.

  Also, the communication unit 87 includes a broadcast image data reception unit, and the encoded image data communicated or broadcast is decoded by the reception unit and converted into image data that can be processed by the color correction device 1 or the color correction device 10. May be. As a result, the input image data is displayed on the output unit 85 by executing the processing steps of the color correction device 1 or the color correction device 10 with the CPU 81 and realizing the digital television.

  Here, the processing step of the color correction apparatus 1 refers to the first coordinate movement amount for moving the color coordinate value of the input image data based on the coordinate movement amount set in advance corresponding to the color coordinate value. A first coordinate movement amount calculating step for calculating, a color weight calculating step for calculating a color weight according to a color coordinate value based on a weight function that decreases from a predetermined color region toward the outside of the color region, A second coordinate movement amount calculation step of calculating a second coordinate movement amount by multiplying the coordinate movement amount of 1 by a color weight, and a coordinate movement step of moving a color coordinate value based on the second coordinate movement amount To do.

  Similarly, the processing steps of the color correction device 10 are the execution step of the color correction device 1, the step of storing image data in the image memory in units of frames or fields, and the step of storing in the image memory. A color component detection step of detecting a color component of a predetermined condition from the image data; an offset value calculation step of creating a histogram of a hue component among the detected color components and calculating an offset value based on the distribution of the histogram; A setting step of setting the calculated offset value in the storage unit may be executed.

  The above processing steps are sequentially executed by the CPU 81 by programs stored in the ROM 82 and the recording unit 86. Here, the RAM 83 may be used for storing the offset value.

  Also, a drive 88 is connected to the bus 91, and a disk 89 such as a magnetic disk, a magneto-optical disk, an optical disk, or a semiconductor memory 90 is appropriately connected, and a computer program read therefrom is recorded as necessary. 86.

  When a series of processing is executed by software, a program constituting the software may be incorporated in advance in a computer with dedicated hardware.

  Various programs may be installed in a computer to execute various functions. For example, in a general-purpose personal computer, various programs are installed via a network. Alternatively, various programs are provided by a recording medium and installed in a personal computer.

  As this recording medium, as shown in FIG. 13, a disc 89 or a semiconductor memory 90 in which a program is recorded may be used separately from the apparatus main body, or it is incorporated in advance in the ROM 82 and recording unit 86 of the apparatus main body. May be provided.

  In the embodiment of the present invention, the HSV color space is used as the color space. However, a color space such as RGB, CMYK, CIE-LAB, YCbCr may be used. For example, in the case of the CIE-LAB color space, since the distance in the color space is proportional to the degree of color difference perceived by humans, it is easy to determine the color weight function, the amount of movement, and the like.

  The HSV color space uses a hexagonal pyramid model, but other approximate models such as a bihexagonal pyramid model may be used.

  According to the color correction device and the image display device of the present invention, it is possible to suppress an abrupt color change and more preferably correct the color of an image. A color television device, a portable terminal, an information processing device, a digital still camera It can be used for image display devices such as printers and image output devices such as printers.

1 is a block diagram of a color correction apparatus according to a first embodiment of the present invention. Block diagram of the color area determination unit in the embodiment Explanatory drawing of the color selection part in the embodiment Block diagram of a color weight calculation unit, a first coordinate movement amount calculation unit, and a second coordinate movement amount calculation unit in the same embodiment (A) Illustration of weight Kh (hue−skin color) in the embodiment (b) Illustration of weight Ks (saturation—skin color) in the embodiment (c) Weight Kv (brightness− in the embodiment) (D) Illustration of weight Kh (hue-sky blue) in the same embodiment (e) Illustration of weight Ks (saturation-sky blue) in the same embodiment (f) In the same embodiment Illustration of weight Kv (lightness-sky blue) (g) Illustration of weight Kh (hue-green) in the embodiment (h) Illustration of weight Ks (saturation-green) in the embodiment (i) Illustration of weight Kv (lightness-green) in the same embodiment Explanatory drawing of the hue weight calculation unit in the same embodiment (A) Illustration of movement amount δh (hue−skin color) in the embodiment (b) Illustration of movement amount δs (saturation—skin color) in the embodiment (c) Movement amount δv in the embodiment (D) Illustrated diagram of movement amount δh (hue-sky blue) in the embodiment (e) Illustrated diagram of displacement amount δs (saturation-sky blue) in the embodiment (f) Illustration of movement amount δv (brightness-sky blue) in the same embodiment (g) Illustration of movement amount δh (hue-green) in the same embodiment (h) Movement amount δs (saturation-in the same embodiment) (I) Illustrative diagram of movement amount δv (lightness-green) in the same embodiment The block diagram of the color correction apparatus in the 2nd Embodiment of this invention Block diagram of the color area determination unit in the embodiment Explanatory drawing of the phase change part in the same embodiment Illustration of RGB color space in the embodiment Explanatory drawing of HSV color space in the same embodiment Block diagram showing the configuration of the computer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Color correction apparatus 2 Color area | region determination part 3 Color weight calculation part 4 1st coordinate movement amount calculation part 5 Color space conversion part 6 Color space reverse conversion part 7 Image analysis part 8 2nd coordinate movement amount calculation part 9 Coordinate movement Unit 21 Color selection unit 22 Phase change unit 24, 25, 26 Register 31 Hue weight calculation unit 32 Saturation weight calculation unit 33 Lightness weight calculation unit 41 Hue movement amount calculation unit 42 Saturation movement amount calculation unit 43 Lightness movement amount calculation unit

Claims (9)

A first coordinate movement amount calculation unit for calculating a first coordinate movement amount for moving the color coordinate value of the input image data based on a coordinate movement amount set in advance corresponding to the color coordinate value;
A color weight calculation unit that calculates a color weight according to the color coordinate value based on a weight function that decreases from a predetermined color region toward the outside of the color region;
A second coordinate movement amount calculation unit for calculating a second coordinate movement amount by multiplying the first coordinate movement amount by the color weight;
A color correction apparatus comprising: a coordinate moving unit that moves the color coordinate value based on the second coordinate movement amount. The color correction apparatus according to claim 1, wherein there are a plurality of color areas, and the color weight calculation unit calculates the color weight for each color area. The color correction apparatus according to claim 1, wherein the color coordinate value is specified from a hue value, a saturation value, and a brightness value. The color correction apparatus according to claim 3, wherein the coordinate movement unit moves the color coordinate value by adding the color coordinate value and the second coordinate movement amount. 4. The color correction apparatus according to claim 3, further comprising a storage unit that can set an offset value for changing a hue value of input image data. An image memory for storing the image data in frame units or field units;
A color component detection unit for detecting a color component of a predetermined condition from the image data stored in the image memory;
Among the detected color components, an offset calculation unit that creates a histogram of hue components and calculates the offset value based on the distribution of the histogram;
The color correction apparatus according to claim 5, further comprising: a setting unit that sets the offset value in the storage unit. The color correction apparatus according to claim 6, wherein the color component of the predetermined condition is a color component in a predetermined saturation region and in a predetermined lightness region. 6. The color correction apparatus according to claim 5, wherein the offset value is determined based on a set color temperature. A data receiving unit for receiving image data transmitted or broadcast;
The color correction device according to claim 1, wherein the color coordinate value of the received image data is moved.
An image display device comprising: a display unit that displays image data of the color coordinate value moved by the color correction device.

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