JP2011004021A - Color correction apparatus, device and method for outputting color correction data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce loads of a built-in CPU concerned with color correction operation.SOLUTION: A method for writing approximate curve data output from an approximate curve generation circuit 112 in an LUT 118 as waveform data of input/output characteristics, is selected. A control part (eCPU) 111 obtains a coefficient of an approximate curve based on a parameter (a gamma value or the like) defining the input/output characteristics received from the external (a control panel or the like) in each frame. The approximate curve generation circuit 112 generates approximate curve data by using the coefficient of the approximate curve obtained by the control part 111 in the preceding frame and writes the generated approximate curve data in the LUT 118 as the waveform data of the input/output characteristics. Since the built-in CPU obtains only the coefficient of the approximate curve based on the parameter received from the external, the loads of the built-in CPU can be reduced. Further, the contents of the LUT 118 are not changed within an active period, so that image disturbance is not generated.

Description

  The present invention relates to a color correction apparatus, a color correction data output apparatus, and a color correction data output method, and more particularly to a color correction apparatus that outputs color correction data with reference to a lookup table.

  Conventionally, for example, Patent Document 1 and the like have proposed a color correction device using a lookup table. Waveform data of input / output characteristics is written in this lookup table. In this color correction apparatus, input image data is corrected using a look-up table to be output image data, and corrections such as brightness, saturation, and hue are performed. In this case, the correction contents differ depending on the waveform data of the input / output characteristics written in the lookup table.

JP 2005-266576 A

  The waveform data of the input / output characteristics written in the lookup table is generated by, for example, an embedded CPU (Embedded Central Processing Unit). That is, a parameter such as a gamma value that defines input / output characteristics is input to the embedded CPU from a control panel or the like, and the embedded CPU obtains waveform data of the input / output characteristics by software calculation based on the parameters. In this case, depending on the calculation speed of the embedded CPU, the processing time of other functions to be performed by the embedded CPU is affected.

  An object of the present invention is to reduce the load on the embedded CPU.

The concept of this invention is
A first color space conversion unit that converts luminance data, blue color difference data, and red color difference data constituting input image data into red, green, and blue three primary color data;
Based on the three primary color data of red, green, and blue obtained by the first color space conversion unit, the three primary color data of red, green, and blue for changing at least one of luminance, saturation, and hue A color correction data output unit for outputting a difference value;
A second color space conversion unit that converts a difference value of the three primary color data of red, green, and blue output from the color correction data output unit into a difference value of luminance data, blue difference data, and red difference data;
The luminance data, blue difference data, and red difference data constituting the input image data are added to the luminance data, blue difference data, and red difference data obtained by the second color space conversion unit, and output. An addition unit for obtaining luminance data, blue color difference data, and red color difference data constituting the image data;
The color correction data output unit is
A coefficient calculation unit for obtaining a coefficient of an approximate curve based on a parameter defining input / output characteristics from the outside;
A circuit module that generates approximate curve data using the coefficient obtained by the coefficient calculation unit;
A look-up table in which approximate curve data generated by the circuit module is written as waveform data of input / output characteristics;
The three primary color data of red, green and blue obtained by the first color space conversion unit are converted into a difference value of the three primary color data of red, green and blue using the lookup table and output. In the color correction device.

  In the present invention, the first color space conversion unit converts luminance data, blue color difference data, and red color difference data constituting the input image data into red, green, and blue three primary color data. Then, the color correction data output unit calculates a difference value between the three primary color data of red, green, and blue for changing at least one of luminance, saturation, and hue based on the three primary color data of red, green, and blue. Is output.

  The color correction data output unit is provided with a lookup table in which waveform data of input / output characteristics is written. The color correction data output unit uses this lookup table to convert the three primary color data of red, green, and blue into a difference value of the three primary color data of red, green, and blue for color correction and output the result. The

  The second color space conversion unit converts the difference values of the three primary color data of red, green, and blue into the difference values of luminance data, blue difference data, and red difference data. Then, the difference data of the luminance data, the blue difference data, and the red difference data is added to the luminance data, the blue difference data, and the red difference data that constitute the input image data by the adding unit, and the luminance data that constitutes the output image data. , Blue difference data and red difference data are obtained.

  In the present invention, waveform data of input / output characteristics is written in the lookup table of the color correction data output unit as follows. That is, the coefficient calculation unit obtains the coefficient of the approximate curve based on the parameter defining the input / output characteristics from the outside (control panel or the like). The circuit module generates approximate curve data using the coefficients of the approximate curve. The approximate curve data generated by the circuit module in this way is written in the lookup table as waveform data of input / output characteristics.

  As described above, the waveform data of the input / output characteristics written in the lookup table is approximate curve data generated in the circuit module. Therefore, for example, the embedded CPU only needs to obtain the coefficient of the approximate curve based on a parameter defining input / output characteristics from the outside as a coefficient calculation unit, and the load is reduced.

In the present invention, for example, the coefficient calculation unit obtains the coefficient of the approximate curve based on the above parameters in the first frame, and the circuit module of the circuit module during the first vertical blanking period of the second frame following the first frame. The circuit module generates approximate curve data using the coefficient written in the register during the vertical blanking period of the second frame, and writes it as the waveform data of the input / output characteristics in the lookup table. May be. In this case, the input / output characteristic waveform data is written to the lookup table within the vertical blanking period, the contents of the lookup table are not changed within the active period, and image disturbance does not occur.
In the case of progressive scan, the operation is performed in units of frames as described above. In the case of interlaced scan, the operation is performed in units of fields.

  In the present invention, for example, the color correction data output unit includes a waveform data generation unit for generating waveform data of input / output characteristics by calculation based on software based on a parameter defining input / output characteristics from the outside, and the waveform data Write the approximate curve data generated by the circuit module as the waveform data of the input / output characteristics to the memory section that temporarily stores the waveform data of the input / output characteristics generated by the generation section, and the memory section. A write control unit that controls whether to write the waveform data of the stored input / output characteristics may be provided.

  The embedded CPU may be in a state where the processing load of other functions is low. In that case, the embedded CPU can calculate the waveform data of the input / output characteristics by software based on the parameters defining the input / output characteristics from the outside, without affecting the processing of other functions. Can be generated. In this case, not the approximate curve data generated by the circuit module but the waveform data with high-accuracy input / output characteristics is written in the lookup table, so that more accurate color correction can be performed.

  In this case, for example, in the first frame, the waveform data generation unit generates the waveform data of the input / output characteristics based on the parameters, writes the waveform data in the memory unit, and the write control unit performs the second following the first frame. The waveform data of the input / output characteristics may be transferred and written to the lookup table during the vertical blanking period at the beginning of the frame.

  In this case, the input / output characteristic waveform data is written to the lookup table within the vertical blanking period, the contents of the lookup table are not changed within the active period, and image disturbance does not occur. In this case, since the waveform data of the input / output characteristics generated by the waveform data generation unit is temporarily stored in the memory unit and then transferred together in a lookup table during the vertical blanking period, the waveform data The calculation speed of the generation unit may be slow, and the calculation load of the embedded CPU can be reduced.

  In the present invention, for example, the color correction data output unit includes a memory unit that temporarily stores waveform data of input / output characteristics generated externally, and approximate curve data generated by a circuit module in a lookup table. May be further provided with a write control unit that controls whether to write waveform data of input / output characteristics or waveform data of input / output characteristics stored in the memory unit. In this case, it is possible to use externally generated waveform data with high precision input / output characteristics in the lookup table.

  In this case, externally generated input / output characteristic waveform data is written to the memory unit in the first frame, and the write control unit uses the vertical blanking period at the head of the second frame following the first frame. The waveform data of the input / output characteristics may be transferred and written to the lookup table.

  In this case, the input / output characteristic waveform data is written to the lookup table within the vertical blanking period, the contents of the lookup table are not changed within the active period, and image disturbance does not occur. In this case, the waveform data of the input / output characteristics generated outside is temporarily stored in the memory unit and then transferred together in the lookup table during the vertical blanking period. The interface can be slow.

  According to this invention, the coefficient of the approximate curve is obtained by the coefficient calculation unit based on the parameters defining the input / output characteristics from the outside (control panel or the like), and the approximation generated by the circuit module using the coefficient of the approximate curve. Curve data is written to the look-up table as waveform data of input / output characteristics, and the embedded CPU only needs to obtain the coefficient of the approximate curve based on parameters defining the input / output characteristics from the outside, for example, as a coefficient calculation unit. , Can reduce the load.

It is a block diagram which shows the structural example of the color correction apparatus as embodiment. It is a block diagram which shows the structural example of the color correction data output part which comprises a color correction apparatus. It is a block diagram which shows the structural example of the approximated curve generation circuit which comprises a color correction data output part. It is a figure which shows the production | generation example of the approximate curve data in an approximate curve generation circuit. It is a figure for demonstrating operation | movement of the color correction data output part at the time of selection of the (A) method of writing the waveform data of the input-output characteristic input from the outside in a lookup table. It is a figure which shows the outline | summary of the whole operation | movement timing at the time of selection of the (A) method of writing the waveform data of the input-output characteristic input from the outside into a lookup table. It is a figure which shows the outline | summary of the operation | movement timing of the transfer writing from a memory part to a lookup table at the time of selection of the method of writing the waveform data of the input-output characteristic input from the outside into a lookup table. It is a figure for demonstrating operation | movement of the color correction data output part at the time of selection of the (B) method of writing the waveform data of the input-output characteristic produced | generated by the control part (eCPU) to a lookup table. It is a figure which shows the outline | summary of the whole operation | movement timing at the time of selection of the (B) method of writing the waveform data of the input-output characteristic produced | generated by the control part (eCPU) to a lookup table. For explaining the operation of the color correction data output unit when selecting the method (C) of writing the approximate curve data generated by the approximate curve generation circuit (circuit module) to the lookup table as the waveform data of the input / output characteristics. FIG. It is a figure which shows the outline | summary of the whole operation | movement timing at the time of selection of the (C) method of writing the approximate curve data produced | generated by the approximate curve production circuit (circuit module) to the look-up table as waveform data of an input / output characteristic. Writing the approximate curve data generated by the approximate curve generation circuit (circuit module) to the look-up table as the waveform data of the input / output characteristics (C) When selecting the method, transfer writing from the approximate curve generation circuit to the look-up table It is a figure which shows the outline | summary of the operation | movement timing. It is a figure which shows an example of the input / output characteristic in a color correction data output part, and an example of the whole input output characteristic in case the color correction effect in a color correction apparatus is ON.

Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described. The description will be given in the following order.
1. Embodiment 2. FIG. Modified example

<1. Embodiment>
[Configuration of color correction device]
An embodiment of the present invention will be described. FIG. 1 shows a configuration example of a color correction apparatus 100 as an embodiment. The color correction apparatus 100 includes an upsampling unit 101, a color space conversion unit 102, a color correction data output unit 103, and multipliers 104R, 104G, and 104B. The color correction apparatus 100 includes a color space conversion unit 105, a downsampling unit 106, adders 107Y and 107C, a delay circuit 108, and limiters 109Y and 109C.

  Image data input to the color correction apparatus 100 is image data in 4: 2: 2 format. This input image data is composed of luminance data Yin (Y) and color data Cin in which blue difference data U (Cb) and red difference data V (Cr) are arranged in a dot sequence.

  The upsampling unit 101 is an interpolation circuit for processing image data in 4: 2: 2 format as image data in 4: 4: 4 format. The upsampling unit 101 is configured to include an interpolation circuit. The upsampling unit 101 performs interpolation processing on each of the color difference data U and V included in the color data Cin, and obtains color difference data U and V that match the sampling frequency of the luminance data Y by doubling the sampling frequency.

  A color space conversion unit (CSC) 102 outputs luminance data Y, blue difference data U, and red difference data V output from the upsampling unit 101, red primary color data R, green primary color data G, and blue primary color data. Convert to B. The color space conversion unit 102 is configured by a matrix circuit, for example. The color space conversion unit 102 constitutes a first color space conversion unit.

  The color correction data output unit 103 outputs the difference values ΔR, ΔG, ΔB of the three primary color data based on the three primary color data R, G, B of red, green, and blue obtained by the color space conversion unit 102. The difference values ΔR, ΔG, ΔB are for changing the black level, white level, gamma characteristic, etc. of each of R, G, B. The color correction data output unit 103 constitutes a primary color correction unit. How to change the black level, the white level, and the gamma characteristic is set based on a user operation, for example. The color correction data output unit 103 enables, for example, white balance adjustment, black balance adjustment, and gamma correction. The detailed configuration of the color correction data output unit 103 will be described later.

  Multipliers 104R, 104G, and 104B multiply the difference values ΔR, ΔG, and ΔB of the three primary color data output from the color correction data output unit 103 by the mask signal MSK. For example, the mask signal MSK is “1” in a region where color correction is performed, and is “0” in a region where color correction is not performed.

  A color space conversion unit (CSC: Color Space Conversion) 105 uses the difference values ΔR, ΔG, ΔB of the three primary color data output from the multipliers 104R, 104G, 104B as the differences between the luminance data, blue difference data, and red difference data. Convert to value. The color space conversion unit 105 includes, for example, a matrix circuit, and performs conversion opposite to that of the color space conversion unit 102 described above. The color space conversion unit 105 constitutes a second color space conversion unit.

  The downsampling unit 106 performs a downsampling process for matching the difference values of the luminance data, the blue color difference data, and the red color difference data output from the color space conversion unit 105 to the 4: 2: 2 format image data. That is, the down-sampling unit 106 performs low-pass filter processing and thinning processing on the difference values of the blue difference data and the red difference data to halve the sampling frequency, and the difference values are arranged in dot order. A difference value of color data is generated.

  The delay circuit 108 is a delay circuit for timing adjustment. By this delay circuit 108, the luminance data Yin and the color data Cin constituting the input image data are synchronized with the timing of the difference value between the luminance data and the color data output from the downsampling unit 106. The adders 107Y and 107C add the difference values of the luminance data and color data supplied from the downsampling unit 106 to the luminance data Yin and color data Cin supplied via the delay circuit 118. The limiters 109Y and 109C perform limiter processing on the output data of the adders 107Y and 107C, and output luminance data Yout and color data Cout as output image data.

[Color correction data output section]
A configuration example of the color correction data output unit 103 will be described. FIG. 2 shows a configuration example of the color correction data output unit 103. The color correction data output unit 103 includes a control unit 111, an approximate curve generation circuit 112, selectors 113 and 114, a memory unit 115, selectors 116 and 117, a lookup table 118, and an address counter 119. ing.

  In the color correction data output unit 103, waveform data of input / output characteristics for converting the three primary color data R, G, B into the difference values ΔR, ΔG, ΔB of the three primary color data is written in the lookup table 118. It is. In this embodiment, the following three methods (A), (B), and (C) are selectively possible as a method of writing data to the lookup table 118.

(A) Write waveform data of input / output characteristics generated externally (such as PC).
(B) Receives parameters defining input / output characteristics from the outside (control panel or the like), and writes the waveform data of the input / output characteristics generated by the internal embedded CPU.
(C) A parameter defining input / output characteristics is received from the outside (control panel, etc.), an approximate curve coefficient is obtained by an internal embedded CPU, and approximate curve data generated by an approximate curve generation circuit as a circuit module is input / output characteristics. Write as data.

  The control unit 111 controls the operation of each unit of the color correction data output unit 103. The control unit 111 is configured by an embedded CPU (eCPU). The control unit 111 selects one of the methods (A), (B), and (C) as a method for writing data to the lookup table 118, and controls the operation of each unit according to the selected method. To do. In this sense, the control unit 111 constitutes a write control unit.

  In addition, when the method (B) is selected as a method for writing data to the lookup table 118, the control unit 111 receives parameters (gamma values, etc.) defining input / output characteristics from the outside (control panel, etc.). . Then, the control unit 111 generates waveform data of input / output characteristics based on the parameters by calculation using software. In this sense, the control unit constitutes a waveform data generation unit.

  In addition, when the method (C) is selected as the method for writing data to the lookup table 118, the control unit 111 receives parameters (gamma values, etc.) defining input / output characteristics from the outside (control panel, etc.). Based on the parameters, the coefficient of the approximate curve is obtained. In this sense, the control unit constitutes a coefficient calculation unit.

  When the method (C) is selected as the method for writing data to the lookup table 118, the approximate curve generation circuit 112 generates approximate curve data using the coefficient obtained by the control unit 111.

[Configuration example of approximate curve generation circuit]
FIG. 3 shows a configuration example of the approximate curve generation circuit 112. The approximate curve generation circuit 112 includes an address counter 121, multipliers 122, 124, 126, adders 123, 125, 127, and a comparator 128. The approximate curve generation circuit 112 includes registers 129-0 to 129- (n-1), 132-0 to 132-n, 134-0 to 134-n, 136-0 to 136-n, 138-0. ˜138-n and selectors 131, 133, 135, and 137.

  The address counter 121 counts from “0” to “1023” when generating the approximate curve data of each primary color data when the three primary color data R, G, and B of red, green, and blue are each 10-bit data. It will be up. The count value of the address counter 121 is output as an address Address. The count value of the address counter 121 is supplied as input data X to the multipliers 122, 124, 126 and the comparator 128.

  The multiplier 122 is supplied with the coefficient A output from the selector 131 and is multiplied by the input data X. The output data A * X of the multiplier 122 is supplied to the adder 123. The adder 123 is supplied with the coefficient B output from the selector 133 and is added to the output data of the multiplier 122. The output data (A * X + B) of the adder 123 is supplied to the multiplier 124. The multiplier 124 multiplies the output data of the adder 123 by the input data X. The output data (A * X + B) * X of the multiplier 124 is supplied to the adder 125.

  The adder 125 is supplied with the coefficient C output from the selector 135 and added to the output data of the multiplier 124. The output data ((A * X + B) * X + C) of the adder 125 is supplied to the multiplier 126. In the multiplier 126, the output data of the adder 125 is multiplied by the input data X. The output data ((A * X + B) * X + C) * X of the multiplier 126 is supplied to the adder 127. The adder 127 is supplied with the coefficient D output from the selector 137 and added to the output data of the multiplier 126. The output data (((A * X + B) * X + C) * X + D) of the adder 127 becomes data Data corresponding to the input data X (address Address) constituting the waveform data of the input / output characteristics.

  In this embodiment, the approximate curve generation circuit 112 divides the input data value X into n sections and generates approximate curve data to be used as waveform data of input / output characteristics. The registers 129-0 to 129- (n-1) hold boundary values Bound P0 to Bound P (n-1) indicating the boundaries of the n sections of the input data X. The boundary values Bound P0 to Bound P (n-1) are given from the control unit 111 together with the coefficients of the approximate curve of each section.

  In the comparator 128, the input data X and the boundary values Bound P0 to Bound P (n-1) are compared to determine which section the current input data X (address Address) is in. The determination result is supplied to the selectors 131, 133, 135, and 137. The registers 132-0 to 132-n hold the coefficients Coeff A0 to Coeff An supplied from the control unit 111, which are the coefficients A of each section. In the selector 131, based on the determination result of the comparator 128, the coefficient of the section to which the input data value X belongs is extracted from the coefficients Coeff A 0 to Coeff An, and is supplied to the multiplier 122 as the coefficient A as described above.

  Further, the registers 134-0 to 134-n hold coefficients Coeff B0 to Coeff Bn supplied from the control unit 111, which are the coefficients B of the respective sections. In the selector 133, the coefficient of the section to which the input data X belongs is extracted from the coefficients Coeff B0 to Coeff Bn based on the determination result of the comparator 128, and is supplied to the adder 123 as the coefficient B as described above.

  Further, the registers 136-0 to 136-n hold coefficients Coeff C0 to Coeff Cn supplied from the control unit 111, which are the coefficients C of each section. In the selector 135, the coefficient of the section to which the input data X belongs is extracted from the coefficients Coeff C0 to Coeff Cn based on the determination result of the comparator 128, and is supplied to the adder 125 as the coefficient C as described above.

  Also, the registers 138-0 to 138-n hold coefficients Coeff D0 to Coeff Dn supplied from the control unit 111, which are the coefficients D of each section. The selector 137 extracts the coefficient of the section to which the input data X belongs from the coefficients Coeff D0 to Coeff Dn based on the determination result of the comparator 128, and supplies the coefficient D to the adder 127 as described above.

  FIG. 4 shows an example of generation of approximate curve data in the approximate curve generation circuit 112. When the input data X (address value Address) is 0 to P0, data on the approximate curve using the coefficients A0, B0, C0, and D0 is generated. Further, when the input data X is from P0 to P1, data on an approximate curve using the coefficients A1, B1, C1, and D1 is generated. Further, when the input data X is P1 to P2, data on an approximate curve using the coefficients A2, B2, C2, and D2 is generated. Further, when the input data X is from P2 to P3, data on the approximate curve using the coefficients A3, B3, C3, and D3 is generated. Although the detailed description is omitted, the same applies to the following.

  Returning to FIG. 2, the selector 113 is controlled by the control unit 111 to generate waveform data of input / output characteristics input from the outside (PC or the like) via an external interface (external I / F), or generated by the control unit 111. The input / output characteristic waveform data is extracted. The selector 113 supplies the extracted waveform data of the input / output characteristics to the memory unit 115 as write data WDAT. The selector 114 takes out an address under the control of the control unit 111 and supplies it to the memory unit 115 as an address ADRS. The address fetched by the selector 114 is an address input from the outside (PC or the like) via an external interface (external I / F), an address generated by the control unit 111, or an address that is a count value of the address counter 119. Either.

  When the method (A) is selected as a method for writing data to the lookup table 118, the selectors 113 and 114 input / output input from the outside (PC or the like) via an external interface (external I / F). Extract the waveform data and address of the characteristic. In addition, when the method (B) is selected as the method of writing data to the lookup table 118, the selectors 113 and 114 take out the waveform data and the address of the input / output characteristics input from the control unit (eCPU) 111. . Further, the selector 114 takes out the count value (read address) of the address counter 119 when transferring the waveform data of the input / output characteristics accumulated in the memory unit 115 to the lookup table 118 as described above.

  When the method (A) is selected as a method for writing data to the lookup table 118, the memory unit 115 receives input / output characteristics from the outside (PC or the like) via an external interface (external I / F). Are temporarily stored (accumulated). The memory unit 115 temporarily stores (accumulates) waveform data of input / output characteristics generated by the control unit 111 when the method (B) is selected as a method of writing data to the lookup table 118. )

  Under the control of the control unit 111, the selector 116 takes out waveform data of input / output characteristics as read data RDAT of the memory unit 115 or approximate curve data from the approximate curve generation circuit 112, and writes the data WDAT to the lookup table 118. Supply as. The selector 117 selectively takes out the address that is the count value of the address counter 119, the address generated by the approximate curve generation circuit 112, or the input primary color data under the control of the control unit 111, and stores the address ADRS in the lookup table 118. Supply as.

  When the selectors 116 and 117 transfer the waveform data of the input / output characteristics stored in the memory unit 115 to the lookup table 118 as described above, the read data RDAT of the memory unit 115 and the count value of the address counter 119 (write address) ). Further, when the method (C) is selected as the method of writing data to the lookup table 118, the selectors 116 and 117 take out the waveform data and address of the input / output characteristics input from the approximate curve generation circuit 112. The selector 117 extracts input primary color data during the active period.

  The lookup table 118 converts the input primary color data into a difference value of the primary color data. In the lookup table 118, the waveform data having the above input / output characteristics is written. The address counter 119 outputs the read address of the memory unit 115 and the write address of the lookup table 118 when transferring the waveform data of the input / output characteristics accumulated in the memory unit 115 to the lookup table 118 as described above. When the three primary color data R, G, and B of red, green, and blue are 10-bit data, the address counter 119 is counted up from “0” to “1023” when transferring the waveform data of the input / output characteristics. To go.

  In FIG. 2, the selectors 113 and 114, the memory unit 115, the selectors 116 and 117, the lookup table 118, and the address counter 119 are one of the three primary color data R, G, and B of red, green, and blue. It corresponds to one primary color data. Accordingly, although not shown in FIG. 2, these portions are provided in parallel in three systems corresponding to the three primary color data R, G, and B of red, green, and blue, respectively.

[Operation of color correction data output section]
The operation of the color correction data output unit 103 shown in FIG. 2 will be described. First, the operation when the method (A) is selected as the method for writing data to the lookup table 118 will be described with reference to FIG. In this case, as described above, the waveform data of the input / output characteristics generated externally (PC or the like) is written into the lookup table 118.

  For each frame, the waveform data and address of the input / output characteristics input from the outside (PC etc.) via the external interface are taken out by the selectors 113 and 114 and supplied to the memory unit 115 as the write data WDAT and the write address ADRS. Is done. Therefore, waveform data of input / output characteristics input from the outside (PC or the like) is stored in the memory unit 115 for each frame.

  In the vertical blanking period at the beginning of each frame, the address counter 119 starts counting up with the switching point as the start timing, and the count value is extracted by the selector 114 and supplied to the memory unit 115 as the read address ADRS. Further, the address which is the count value of the address counter 119 is taken out by the selector 117 and supplied to the lookup table 118 as the write address ADRS.

  The waveform data of the input / output characteristics accumulated in each frame in the memory unit 115 is read out in the vertical blanking period at the head of the subsequent frame. This read data RDAT is taken out by the selector 116 and supplied to the lookup table 118 as write data WDAT. Therefore, waveform data of input / output characteristics input from the outside (PC or the like) is written in the lookup table 118 for each frame during the leading vertical blanking period.

  In the active period of each frame, the input primary color data is extracted by the selector 117 and supplied to the lookup table 118 as a read address ADRS. Therefore, in this lookup table 118, the difference value of the primary color data corresponding to the input primary color data is read and used as the output of the color correction data output unit 103.

  FIG. 6 shows an overview of the overall operation timing. In the A frame, waveform data of input / output characteristics input from the outside (PC or the like) is written in the memory unit 115. Then, in the vertical blanking period at the head of the B frame following the A frame, the waveform data of the input / output characteristics accumulated in the memory unit 115 in the A frame is transferred to the lookup table 118 and written therein. In the active period of the B frame, the written waveform data of the input / output characteristics is held and used as it is.

  FIG. 7 shows an outline of the operation timing of transfer writing from the memory unit 115 to the lookup table 118. In this case, the waveform data of the input / output characteristics stored in the memory unit 115 in the A frame is transferred to the lookup table 118 at a high speed with a switching point in the vertical blanking period at the head of the B frame as a trigger. Written. In FIG. 7, “LUT1”, “LUT2”,..., “LUTn” indicate waveform data of input / output characteristics corresponding to a certain primary color data. Therefore, when the three primary color data R, G, and B of red, green, and blue are only one system, there are three “LUT1”, “LUT2”, and “LUT3”, but here, red, green Suppose that there are a plurality of blue three primary color data R, G, B, and so on, n.

  Next, the operation when the method (B) is selected as the method for writing data to the lookup table 118 will be described with reference to FIG. In this case, as described above, the waveform of the input / output characteristic generated by the internal embedded CPU based on the parameter (gamma value, etc.) defining the input / output characteristic from the outside (control panel or the like) is stored in the lookup table 118. Data is written.

  The control unit (eCPU) 111 receives a parameter (gamma value or the like) defining input / output characteristics from the outside (control panel or the like) via an external interface (external I / F) for each frame. Then, the control unit 111 generates waveform data of input / output characteristics by calculation by software based on the parameters received in the previous frame for each frame. In this case, waveform data of three input / output characteristics is sequentially generated corresponding to one system of the three primary color data R, G, and B of red, green, and blue. Therefore, when there are a plurality of three primary color data R, G, and B of red, green, and blue, waveform data of multiple input / output characteristics is sequentially generated.

  The waveform data and address of the input / output characteristics generated by the control unit 111 are taken out by the selectors 113 and 114 and supplied to the memory unit 115 as the write data WDAT and the write address ADRS. For this reason, waveform data of input / output characteristics generated by the control unit 111 is accumulated in the memory unit 115 for each frame.

  In the vertical blanking period at the beginning of each frame, the address counter 119 starts counting up with the switching point as the start timing, and the count value is extracted by the selector 114 and supplied to the memory unit 115 as the read address ADRS. Further, the address which is the count value of the address counter 119 is taken out by the selector 117 and supplied to the lookup table 118 as the write address ADRS.

  The waveform data of the input / output characteristics accumulated in each frame in the memory unit 115 is read out in the vertical blanking period at the head of the subsequent frame. This read data RDAT is taken out by the selector 116 and supplied to the lookup table 118 as write data WDAT. Therefore, the input / output characteristic waveform data generated by the control unit 111 is written in the lookup table 118 for each frame during the leading vertical blanking period.

  In the active period of each frame, the input primary color data is extracted by the selector 117 and supplied to the lookup table 118 as a read address ADRS. Therefore, in this lookup table 118, the difference value of the primary color data corresponding to the input primary color data is read and used as the output of the color correction data output unit 103.

  FIG. 9 shows an overview of the overall operation timing. In the A frame, the control unit 111 receives a parameter (gamma value or the like) defining input / output characteristics from the outside (control panel or the like). Then, in the B frame following the A frame, the waveform data of the input / output characteristics generated by the control unit 111 is written in the memory unit 115. Then, in the vertical blanking period at the head of the C frame following the B frame, the waveform data of the input / output characteristics accumulated in the memory unit 115 in the B frame is transferred to the lookup table 118 and written therein. In the active period of the C frame, the written waveform data of the input / output characteristics is held and used as it is.

  The operation timing of transfer writing from the memory unit 115 to the lookup table 118 in this case is the same as that in the case where the method (A) is selected as the method of writing data to the lookup table 118 described above ( (See FIG. 7).

  Next, the operation when the method (C) is selected as the method for writing data to the lookup table 118 will be described with reference to FIG. In this case, as described above, the approximate curve data generated by the approximate curve generation circuit 112 is written in the lookup table 118. In this case, the coefficient of the approximate curve obtained by the control unit 111 based on parameters defining input / output characteristics from the outside (control panel or the like) is used.

  The control unit (eCPU) 111 receives a parameter (gamma value or the like) defining input / output characteristics from the outside (control panel or the like) via an external interface (external I / F) for each frame. Then, the control unit 111 obtains an approximate curve coefficient for each frame based on the parameters received in the previous frame.

  In the approximate curve generation circuit 112 (see FIG. 3), in the vertical blanking period at the head of each frame, the coefficient of the approximate curve obtained by the control unit 111 in the previous frame is set in the register, and the switching point is set as the start timing. Approximate curve data is generated. In this case, three pieces of approximate curve data are sequentially generated corresponding to one system of the three primary color data R, G, and B of red, green, and blue. Therefore, when there are a plurality of three primary color data R, G, and B of red, green, and blue, multiple approximate curve data are sequentially generated.

  The approximate curve data and address generated by the approximate curve generation circuit 112 are taken out by the selectors 116 and 117 and supplied to the lookup table 118 as write data WDAT and write address ADRS. Therefore, the approximate curve data generated by the approximate curve generation circuit 112 is written in the lookup table 118 as waveform data of input / output characteristics for each frame during the leading vertical blanking period.

  In the active period of each frame, the input primary color data is extracted by the selector 117 and supplied to the lookup table 118 as a read address ADRS. Therefore, in this lookup table 118, the difference value of the primary color data corresponding to the input primary color data is read and used as the output of the color correction data output unit 103.

  FIG. 11 shows an overview of the overall operation timing. In the A frame, the control unit 111 receives a parameter (gamma value or the like) defining input / output characteristics from the outside (control panel or the like). Then, in the B frame following the A frame, the control unit 111 obtains the coefficient of the approximate curve.

  In the vertical blanking period at the beginning of the C frame following the B frame, the approximate curve data generated by the approximate curve generation circuit 112 with the coefficient of the approximate curve obtained in the B frame is used as the waveform data of the input / output characteristics. It is written in the up table 118. In the active period of the C frame, the written waveform data of the input / output characteristics is held and used as it is.

  FIG. 12 shows an outline of the operation timing of transfer writing from the approximate curve generation circuit 112 to the lookup table 118. In this case, the coefficient of the approximate curve obtained by the control unit 111 in the B frame is set in the register of the approximate curve generation circuit 112 in the vertical blanking period at the head of the C frame. Then, generation of approximate curve data is started with the switching point as a trigger, and is written in the lookup table 118. In FIG. 12, “LUT1”, “LUT2”,..., “LUTn” indicate waveform data of input / output characteristics corresponding to a certain primary color data. Therefore, when the three primary color data R, G, and B of red, green, and blue are only one system, there are three “LUT1”, “LUT2”, and “LUT3”, but here, red, green Suppose that there are a plurality of blue three primary color data R, G, B, and so on, n.

[Operation of color correction device]
The operation of the color correction apparatus 100 shown in FIG. 1 will be described. Luminance data Yin and color data Cin (dot sequential data of blue difference data U and red difference data V) constituting input image data (4: 2: 2 format image data) are subjected to timing adjustment by delay circuit 108. Are supplied to the adders 107Y and 107C.

  Further, the luminance data Yin and the color data Cin constituting the input image data are supplied to the upsampling unit 101. In the upsampling unit 101, the color difference data U and V included in the color data Cin are subjected to interpolation processing, the sampling frequency is doubled, and the color difference data U and V matched with the sampling frequency of the luminance data Y is obtained. Is obtained.

  The luminance data Y, the blue color difference data U, and the red color difference data V output from the upsampling unit 101 are supplied to the color space conversion unit 102. In the color space conversion unit 102, the luminance data Y, the blue color difference data U, and the red color difference data V are converted into the three primary color data R, G, and B of red, green, and blue, for example, by matrix processing.

  The three primary color data R, G, and B obtained by the color space conversion unit 102 are supplied to the color correction data output unit 103. In this color correction data output unit 103, 3 for changing the black level, white level, gamma characteristic, etc. based on the three primary color data R, G, B of red, green and blue obtained by the color space conversion unit 102. Difference values ΔR, ΔG, ΔB of the primary color data are output. Here, how to change the black level, the white level, and the gamma characteristic is set based on a user operation, for example, and the input / output characteristic written in the lookup table 118 (see FIG. 2) of the color correction data output unit 103. The waveform data of is in accordance with the setting.

  FIG. 13A shows an example of input / output characteristics in the color correction data output unit 103. A curve r indicates the correspondence between the input red primary color data R and the difference value ΔR between the output red primary color data. A curve g indicates the correspondence between the input green primary color data G and the difference value ΔG between the output green primary color data. A curve b shows the correspondence between the input blue primary color data B and the output blue primary color data difference value ΔB.

  The difference values ΔR, ΔG, ΔB of the three primary color data output from the color correction data output unit 103 are supplied to the color space conversion unit 105 via the multipliers 104R, 104G, 104B. In the multipliers 104R, 104G, and 104B, the difference values ΔR, ΔG, and ΔB of the three primary color data for color change output from the color correction data output unit 103 are multiplied by the mask signal MSK. In the color space conversion unit 105, the difference values of the three primary color data supplied from the multipliers 104R, 104G, and 104B are converted into the difference values of luminance data, blue difference data, and red difference data, for example, by matrix processing.

  The difference values of the luminance data, the blue color difference data, and the red color difference data obtained by the color space conversion unit 105 are supplied to the downsampling unit 106. The downsampling unit 106 performs downsampling processing for matching the difference values of the luminance data, the blue color difference data, and the red color difference data output from the color space conversion unit 105 to the image data in the 4: 2: 2 format. Done. That is, in the downsampling unit 106, the difference value between the blue difference data and the red difference data is subjected to a low pass filter process and a thinning process, the sampling frequency is halved, and these difference values are dot-sequentially. A difference value between the arranged color data is generated.

  Difference values between the luminance data and the color data output from the downsampling unit 106 are supplied to adders 107Y and 107C. In the adders 107Y and 107C, the luminance data Yin and color data Cin supplied via the delay circuit 108 are added with the difference values of the luminance data and color data supplied from the downsampling unit 106. The output data of the adders 107Y and 107C are output as luminance data Yout and color data Cout constituting the output image data via the limiters 109Y and 109C.

  Here, the mask signal MSK is set to “0” in an area where color correction is not performed, and the color correction effect is turned off in this area. In this case, the difference values of the three primary color data output from the multipliers 104R, 104G, and 104B are all zero. Therefore, all the difference values of the luminance data and color data supplied from the downsampling unit 106 to the adders 107Y and 107C are also zero. Therefore, the output data of the adders 107Y and 107C is luminance data Yin and color data Cin itself.

  On the other hand, the square signal MSK is set to “1” in the area where color correction is performed, and the color correction effect is turned on in this area. In this case, the difference values of the three primary color data output from the multipliers 104R, 104G, and 104B are the difference values ΔR, ΔG, and ΔB of the three primary color data output from the color correction data output unit 103. Therefore, the luminance data and color data difference values supplied from the downsampling unit 106 to the adders 107Y and 107C have values corresponding to the three primary color data difference values ΔR, ΔG, and ΔB. Therefore, the output data of the adders 107Y and 107C is obtained by adding the brightness data for color correction and the difference value of the color data to the brightness data Yin and the color data Cin.

  FIG. 13B shows an example of overall input / output characteristics when the color correction effect is on in the color correction apparatus 100. In this example, the input / output characteristics of the color correction data output unit 103 are shown in FIG. 13A, and the input / output relationship of the three primary color data is shown. A curve r indicates the input / output characteristics of the red primary color data R. A curve g indicates input / output characteristics of the green primary color data G. A curve b indicates input / output characteristics of the blue primary color data B.

  As described above, in the color correction apparatus 100 shown in FIG. 1, as a method for writing data to the lookup table 118 of the color correction data output unit 103, the approximate curve data generated by the approximate curve generation circuit 112 is input / output characteristics waveform. The method of writing as data can be selected. In that case, the built-in CPU (eCPU) of the control unit 111 only needs to obtain the coefficient of the approximate curve based on a parameter (gamma value or the like) defining input / output characteristics from the outside (control panel or the like), for example. Is reduced.

  In the color correction apparatus 100 shown in FIG. 1, the writing of the approximate curve data to the lookup table 118 of the color correction data output unit 103 is performed within the vertical blanking period. Therefore, the contents of the lookup table 118 are not changed within the active period, and the occurrence of image disturbance is prevented.

  Further, in the color correction apparatus 100 shown in FIG. 1, as a method of writing data to the lookup table 118 of the color correction data output unit 103, a method of writing waveform data of input / output characteristics generated by the control unit (eCPU) 111. Can be selected. When the processing load of other functions is low, the embedded CPU does not affect the processing of other functions, and does not affect the input / output based on the parameters that define the input / output characteristics from the outside (control panel, etc.) It becomes possible to generate waveform data of characteristics by calculation by software. In this case, not the approximate curve data generated by the approximate curve generation circuit 112 but the waveform data with high-accuracy input / output characteristics is written in the lookup table 118, so that more accurate color correction can be performed.

  In the color correction apparatus 100 shown in FIG. 1, the input / output characteristic waveform data generated by the control unit (eCPU) 111 is written into the lookup table 118 within the vertical blanking period. Therefore, the contents of the lookup table 118 are not changed within the active period, and image disturbance does not occur. In this case, the waveform data of the input / output characteristics generated by the control unit (eCPU) 111 is temporarily stored in the memory unit 115 and then transferred to the lookup table 118 in a vertical blanking period. Written. Therefore, the calculation speed of the control unit (eCPU) 111 may be slow, and the calculation load of the embedded CPU can be reduced.

  In the color correction apparatus 100 shown in FIG. 1, as a method for writing data to the lookup table 118 of the color correction data output unit 103, a method of writing waveform data of input / output characteristics generated externally (such as a PC) is used. You can choose. For this reason, externally generated waveform data with high precision input / output characteristics can be written into the lookup table 118 of the color correction data output unit 103 and used.

  In the color correction apparatus 100 shown in FIG. 1, the input / output characteristic waveform data from the outside (PC or the like) is written into the lookup table 118 within the vertical blanking period. Therefore, the contents of the lookup table 118 are not changed within the active period, and image disturbance does not occur. In this case, the waveform data of the input / output characteristics from the outside (PC or the like) is temporarily stored in the memory unit 115 and then transferred and written together in the lookup table 118 in the vertical blanking period. Therefore, the interface with the outside (external interface) may be low speed.

<2. Modification>
In the above-described embodiment, the color correction apparatus 100 shown in FIG. 1 is configured to control a region where the color correction effect is turned on / off by the mask signal MSK. However, in addition to the color correction effect on / off control, or instead of the color correction effect on / off control, an overall on / off control of the color correction effect may be considered. In this case, for example, a switch circuit is provided between the downsampling unit 106 and the adders 107Y and 107C, and when the color correction effect is turned on, the switch circuit is turned on.
In the above-described embodiment, the case of progressive scan has been described, and the operation is performed in units of frames as described above. However, in the case of interlaced scanning, it is a matter of course that the operation is performed in units of fields. That is, “frame” is replaced with “field”.

  Although not described above, the setting of the method for writing the waveform data of the input / output characteristics in the lookup table 118 in the color correction data output unit 103 is, for example, based on the user operation (A) to (C). This is done by selecting one of the methods. Further, the switching of the writing method of the waveform data of the input / output characteristics to the lookup table 118 may be automatically performed under the control of the control unit 111. For example, in the switching between the method (B) and the method (C), the following switching can be considered. That is, when the load of the embedded CPU of the control unit 111 is increased by other processing, the method is switched to the method (C) to reduce the load, and conversely, when the load of the embedded CPU is small, the method is switched to the method (B). To improve color correction accuracy.

  The present invention can reduce the load of an embedded CPU related to a color correction operation, and can be applied to, for example, a color correction circuit of a broadcasting device, a video camera, a television receiver, or the like.

  DESCRIPTION OF SYMBOLS 100 ... Color correction apparatus, 101 ... Upsampling part, 102 ... Color space conversion part, 103 ... Color correction data output part, 104R, 104G, 104B ... Multiplier, 105 ... Color space conversion unit 106... Downsampling unit 107 Y and 107 C... Adder 108. Delay circuit 109 Y and 109 C Limiter 111 Control unit (eCPU) 112. Approximate curve generation circuit, 113, 114 ... selector, 115 ... memory unit, 116, 117 ... selector, 118 ... lookup table, 119 ... address counter, 121 ... address counter 122, 124, 126 ... multipliers, 123, 125, 127 ... adders, 128 ... comparators, 129-0 to 129- (n-1). Register, 131, 133, 135 and 137 ... selector, 132-0~132-n, 134-0~134-n, 136-0~136-n, 138-0~138-n ··· register

Claims (8)

A first color space conversion unit that converts luminance data, blue color difference data, and red color difference data constituting input image data into red, green, and blue three primary color data;
Based on the three primary color data of red, green, and blue obtained by the first color space conversion unit, the three primary color data of red, green, and blue for changing at least one of luminance, saturation, and hue A color correction data output unit for outputting a difference value;
A second color space conversion unit that converts a difference value of the three primary color data of red, green, and blue output from the color correction data output unit into a difference value of luminance data, blue difference data, and red difference data;
The luminance data, blue difference data, and red difference data constituting the input image data are added to the luminance data, blue difference data, and red difference data obtained by the second color space conversion unit, and output. An addition unit for obtaining luminance data, blue color difference data, and red color difference data constituting the image data;
The color correction data output unit is
A coefficient calculation unit for obtaining a coefficient of an approximate curve based on a parameter defining input / output characteristics from the outside;
A circuit module that generates approximate curve data using the coefficient obtained by the coefficient calculation unit;
A look-up table in which approximate curve data generated by the circuit module is written as waveform data of input / output characteristics;
The three primary color data of red, green and blue obtained by the first color space conversion unit are converted into a difference value of the three primary color data of red, green and blue using the lookup table and output. Color correction device. The coefficient calculation unit obtains a coefficient of the approximate curve based on the parameter in the first frame, and stores the coefficient in the register of the circuit module in the vertical blanking period at the head of the second frame following the first frame. writing,
The circuit module generates the approximate curve data using the coefficient written in the register during the vertical blanking period of the second frame, and writes it as the waveform data of the input / output characteristics in the lookup table. Item 2. The color correction apparatus according to Item 1. The color correction data output unit is
A waveform data generation unit for generating waveform data of input / output characteristics by calculation based on software based on the parameters defining the input / output characteristics from the outside;
A memory unit for temporarily storing the waveform data of the input / output characteristics generated by the waveform data generation unit;
Write control unit for controlling whether approximate curve data generated by the circuit module is written as waveform data of input / output characteristics or waveform data of input / output characteristics stored in the memory unit to the lookup table The color correction apparatus according to claim 1, further comprising: The waveform data generation unit generates waveform data of the input / output characteristics based on the parameters in the first frame, writes the waveform data to the memory unit,
When writing the waveform data of the input / output characteristics stored in the memory unit to the lookup table, the write control unit is configured to store the memory in the vertical blanking period at the head of the second frame following the first frame. The color correction apparatus according to claim 3, wherein the waveform data of the input / output characteristics is transferred from the unit to the lookup table and written. The color correction data output unit is
A memory unit for temporarily storing waveform data of externally generated input / output characteristics;
Write control unit for controlling whether approximate curve data generated by the circuit module is written as waveform data of input / output characteristics or waveform data of input / output characteristics stored in the memory unit to the lookup table The color correction apparatus according to claim 1, further comprising: In the first frame, the waveform data of the input / output characteristics generated externally is written in the memory unit,
When writing the waveform data of the input / output characteristics stored in the memory unit to the lookup table, the write control unit is configured to store the memory in the vertical blanking period at the head of the second frame following the first frame. The color correction apparatus according to claim 5, wherein the waveform data of the input / output characteristics is transferred from the input unit to the lookup table and written. A coefficient calculation unit for obtaining a coefficient of an approximate curve based on a parameter defining input / output characteristics from the outside;
A circuit module that generates approximate curve data using the coefficient obtained by the coefficient calculation unit;
A lookup table in which approximate curve data generated by the circuit module is written as waveform data of input / output characteristics;
Using the above lookup table, the red, green and blue three primary color data are converted into differential values of the three primary color data of red, green and blue for changing at least one of luminance, saturation and hue. Output color correction data output device. A color correction data output method for outputting a difference value of three primary color data of red, green, and blue for changing at least one of luminance, saturation, and hue based on the three primary color data of red, green, and blue. And
A coefficient calculation step for obtaining a coefficient of the approximate curve based on parameters defining input / output characteristics from the outside;
An approximate curve data generation step for generating approximate curve data by the circuit module using the coefficient obtained in the coefficient calculation step;
A waveform data writing step for writing the approximate curve data generated in the approximate curve data generation step as waveform data of input / output characteristics in a lookup table;
A correction data output step for converting the three primary color data of red, green and blue into a difference value of the three primary color data of red, green and blue using the lookup table and outputting the difference data; Method.

Images