JP4573491B2 - Image processing apparatus and image processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing technique, and more particularly to a technique for displaying a mixture of a plurality of images.
[0002]
[Prior art]
New broadcasting forms and services have been proposed for the start of digital broadcasting. One of them is an on-screen display (OSD) that displays an arbitrary character or symbol (character) superimposed on a screen of a broadcast video.
With OSD, for example, it is possible to display a caption superimpose on the screen, to display a breaking news, or to display an electronic program guide (EPG) or the like. These sub-images are given an α value as an index of transparency, and are mixed with the broadcast screen as the main image with an arbitrary transparency.
[0003]
Figure 1 shows the standard “Data Broadcast Coding and Transmission System in Digital Broadcasting” (ARIB STD-B24 3.0 Edition (first volume), published on October 26, 1999, published by the Japan Radio Industry Association. It is explanatory drawing of the synthetic | combination control between planes published on the 19th page of May 31, 2001 revision 3.0). The pixel (SP) of the still image plane and the pixel (VP) of the moving image plane are switched by a 1-bit value (CP) of the moving image still image switching plane. Therefore, the pixel (SVP) of the combined plane of the moving image plane and the still image plane follows the following equation.
SVP = SP (when CP = 1)
VP (when CP = 0)
The pixels of the synthesis plane in which the moving image and the still image are synthesized are further synthesized by the pixel (TP) of the character graphic plane and the α value output from the CLUT. When this α value is α1, the pixel (TSVP) of the composite plane is expressed by the following equation.
TSVP = (1−α1) × SVP + α1 × TP
The subtitle plane pixels (GP) are further synthesized by the α value output from the subtitle plane CLUT. When this α value is α2, the pixel (GTSVP) of the synthesis plane is represented by the following equation.
GTSVP = (1−α2) × TSVP + α2 × GP
[0004]
[Problems to be solved by the invention]
In order to minimize the time required for image synthesis and reduce the delay from reception of broadcast waves to display, the OSD function is generally realized mainly by a hardware configuration. However, in order to further reduce the size and weight of the apparatus, it is required to simplify the hardware configuration and realize the OSD function with as few configurations as possible.
[0005]
The present invention has been made in view of such problems, and an object thereof is to provide a technique for simplifying a hardware configuration necessary for image processing.
[0006]
[Means for Solving the Problems]
One embodiment of the present invention relates to an image processing apparatus. The image processing apparatus includes a combining unit that mixes the pixel value A of the first image and the pixel value B of at least one second image combined with the first image with a predetermined mixing coefficient α. A first input unit that inputs the pixel value A to the combining unit, a second input unit that inputs an index value that specifies the pixel value B to the combining unit, and a mixing coefficient α and a pixel value B for each index A table recorded in association with each other, the table holds α × B obtained by multiplying the pixel value B by the mixing coefficient α in advance, and is included in the calculation of (1−α) × A + α × B in the synthesis unit. Among these multiplications, (1−α) × A is calculated by a multiplier, and α × B is obtained by reading data from the table.
[0007]
Even when three or more images are combined, assuming that the pixel value of the combined image up to the previous stage is C and the pixel value of the image to be combined is D, among the operations of (1−α) × C + α × D, By acquiring α × D by reading data from the table, the multiplier used for the calculation of α × D becomes unnecessary. Thereby, the hardware configuration can be simplified.
[0008]
Another embodiment of the present invention relates to an image processing method. In this image processing method, in a table in which a mixture coefficient α and pixel data B are recorded as a set for each index, α × B obtained by multiplying the mixture coefficient α in advance as pixel data B is recorded, When an image formed by the pixel data B is mixed with another image formed by the pixel data A, α × B of the multiplications included in the calculation of (1−α) × A + α × B is calculated from the table. Act by data reading. By reading data from the table, the number of hardware multipliers may be reduced.
[0009]
It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, etc. are also effective as an aspect of the present invention.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 2 shows an overall configuration of a television receiver 10 as an example of an image processing apparatus according to an embodiment of the present invention. In addition to the general function of a television receiver that reproduces and outputs video and audio from a broadcast wave, the television receiver 10 includes a first image (hereinafter also referred to as a “main image”) sent by the broadcast wave. In addition, at least one second image including character information or the like (hereinafter also referred to as “sub-image”) is superimposed and output. The first image may be acquired by any method such as terrestrial broadcasting, satellite broadcasting, and cable broadcasting, or may be in any format such as analog, digital, and hybrid. In this embodiment, a digital broadcast receiver will be described as an example.
[0011]
The broadcast wave received by the antenna 12 is sent to the tuner 14. The tuner 14 selects a transponder including a channel selected by the user and performs QPSK demodulation. A stream including a plurality of transport packets obtained by demodulation is sent to the packet separation unit 16. The packet separator 16 is a demultiplexer and separates a packet corresponding to a desired channel and outputs it to the decoder 18. The decoder 18 is, for example, an MPEG decoder, decodes the input packet, and outputs audio data to the audio signal processing unit 30 and video data to the video signal processing unit 32. At this time, when the sub image data is included in the broadcast wave, the sub image data is output to the main control unit 20 or the sub image input unit 34.
[0012]
The audio signal processing unit 30 performs predetermined processing on the input audio data and outputs it to the speaker 40. The video signal processing unit 32 performs predetermined processing on the input video data and outputs the processed data to the synthesis unit 36. The sub image input unit 34 acquires the sub image data and outputs it to the synthesis unit 36. As will be described in detail later, the combining unit 36 combines the main image data and the sub image data, and outputs the combined data to the NTSC encoder 38. The video signal converted into a video signal by the NTSC encoder 38 is output to the monitor 42 and displayed. Note that video data or audio data may be output to any external device as a digital signal.
[0013]
The main control unit 20 comprehensively controls the entire television receiver 10. The main control unit 20 includes a CPU 22, a ROM 24 that stores programs necessary for system startup, and a DRAM 26 that is used as a program area or work area. The main control unit 20 performs predetermined processing on the sub-image data acquired from the broadcast wave via the decoder 18 or from the outside via the communication unit 28 that supports a communication format different from the broadcast wave, and the processed data Is sent to the sub-image input unit 34. In addition, the main control unit 20 may generate a sub-image such as an electronic program guide in response to a request from the user and send it to the sub-image input unit 34.
[0014]
FIG. 3 is a diagram for explaining a general configuration and operation of the synthesis unit 36. In this example, two sub-images (layer B and layer C) are combined with the main image (layer A). For example, the layer A corresponds to the moving image plane VP or the still image plane SP in FIG. 1, the layer B corresponds to the character graphic plane TP, and the layer C corresponds to the caption plane GP. The video data of layer A is input to the synthesis unit 36 via the video signal processing unit 32. In general, the video data of layer A includes a luminance signal Y and color difference signals Cb and Cr, each of which is composed of 4 pixels, 4, 4, 4 bytes, or 4, 2, 2 bytes. When the color difference signals Cb and Cr are composed of 2 bytes, as shown in FIG. 1, the color difference signals Cb and Cr may be converted into 4 bytes by the 422 → 444 conversion unit and then input to the synthesis unit 36. In this example, the video data of layer B and layer C is given as an 8-bit index signal. With reference to the color look-up tables 100b and 100c, the luminance signal Y and the color difference signals Cb, Cr corresponding to the index signal are given. , And the mixing coefficient α is read out. The calculation in the combining unit 36 is performed for each pixel value of Y, Cb, and Cr. Here, for convenience of explanation, the pixel value of the layer A is “A” and the pixel value of the layer B is “B”. The pixel value of layer C is represented by “C”.
[0015]
FIG. 4 shows internal data of the color lookup tables 100b and 100c. The color lookup tables 100b and 100c are provided with an index field 300, a mixing coefficient α value field 302, a luminance signal Y value field 304, a color difference signal Cb value field 306, and a color difference signal Cr value field 308. When the index signal “0” is designated as the pixel value of a certain pixel in the layer B, the α value “1”, the Y value “200”, the Cb value “100”, the Cr value corresponding to the index “0” “100” is read and output to the circuit of the combining unit 36. The layer B color lookup table 100b and the layer C color lookup table 100c may use the same table in common.
[0016]
Returning to FIG. 3, the image composition procedure will be described. First, the pixel value A of layer A and the pixel value B of layer B are synthesized by the synthesis circuit at the first stage. Here, as described with reference to FIG._BThen, the pixel value D of the composite layer is expressed by the following equation.
D = (1−α_B) × A + α_B× B
In order to calculate the pixel value D of the synthesis layer D, first, the mixing coefficient α corresponding to the designated index signal is retrieved from the color lookup table 100b._BAnd the pixel value B is read out. Then, the multiplier 110 receives the pixel value A of the layer A and the mixing coefficient α._B1-α calculated from_BAnd enter (1-α_B) XA is calculated.
Further, the multiplier 112 receives the pixel value B of the layer B and the mixing coefficient α._BAnd enter_BCalculate xB. Furthermore, the pixel value D of a synthetic | combination layer is output by inputting and adding each calculation result to the adder 120.
[0017]
Similarly, the pixel value D of the synthesis layer D and the pixel value C of the layer C are synthesized by the synthesis circuit at the second stage. That is, α_CXC is calculated and is multiplied by (1−α) by the multiplier 114._C) × D is calculated and added by the adder 122. The output pixel value E of the composition layer E is expressed by the following equation.
E = (1-α_C) × D + α_C× C
= (1-α_B) (1-α_CA + α_B(1-α_C) B + α_CC
The synthesized video signal is output to the NTSC encoder 38.
[0018]
In the synthesis circuit shown in FIG. 3, at each stage of synthesis, a multiplier that multiplies the pixel value of the synthesis layer up to the previous stage by (1-α) and a multiplier that multiplies the pixel value of the layer to be synthesized by α. Are required, and 2n multipliers are required to synthesize the n layers. Actually, 2n × 3 multipliers are required to combine the luminance signal Y and the color difference signals Cb and Cr. In order to further reduce the size and weight of the device, it is preferable to simplify the circuit configuration in the combining unit 36 and reduce the hardware configuration.
[0019]
FIG. 5 is a diagram for explaining the configuration and operation of the improved combining unit 36. FIG. 6 shows the internal data of the color lookup tables 102b and 102c used in the combining unit 36 shown in FIG. FIG.
[0020]
The color lookup tables 102b and 102c shown in FIG.
An index column 300, a 1-α value column 312, an αY value column 314, an αCb value column 316, and an αCr value column 318 are provided. For example, as a pixel value of a certain pixel in the layer B, an index signal “0” is provided. Is designated, the 1-α value “0”, αY value “200”, αCb value “100”, and αCr value “100” corresponding to the index “0” are read out to the circuit of the combining unit 36. Is output. In this way, instead of the values of Y, Cb, and Cr, by storing the values obtained by multiplying the respective values in advance in the table, the multiplier used for multiplying the pixel value and α becomes unnecessary. . The color lookup table 102 may be held fixedly, but when the table is updated, each data of the color lookup table 102 may be calculated by the CPU 22 or the like, for example.
[0021]
Returning to FIG. 5, the image composition procedure will be described. Pixel value A of layer A and 1-α read out from the color lookup table 102b_BAre respectively input to the multiplier 130 and (1-α_B) × A is calculated. Then, the calculation result and α read out from the color lookup table 102b._BB is input to the adder 140, and the pixel value D of the synthesis layer D = (1−α_BA + α_BB is output.
[0022]
Similarly, the pixel value D of the synthesis layer D and the pixel value C of the layer C are synthesized. That is, the multiplier 132 (1−α_C) × D is calculated, and α is read from the color lookup table 102c by the adder 142 as a result of the calculation._CC is added. The output pixel value E of the synthesis layer E is the same as that in FIG.
E = (1-α_C) × D + α_C× C
= (1-α_B) (1-α_CA + α_B(1-α_C) B + α_CC
The synthesized video signal is output to the NTSC encoder 38.
[0023]
The synthesis unit 36 shown in FIG. 5 records a value obtained by multiplying the pixel value by the mixing coefficient α in the color lookup table 102 for reading out the pixel value of the sub-image, and mixes the layers. Of the multiplications included in the calculation of (1-α) × A + α × B, α × B is substituted for data reading from the table, so the number of multipliers is halved compared to the combining unit 36 shown in FIG. Can be. This can reduce the hardware configuration and contribute to further downsizing and weight reduction of the apparatus. Further, power consumption can be reduced by reducing the hardware configuration.
[0024]
(Second Embodiment)
FIG. 7 shows an internal configuration of the combining unit of the television receiver according to the second embodiment. The synthesizing unit 36 of the present embodiment does not synthesize the sub-images to the main image one by one, but synthesizes a plurality of sub-images first, and finally combines the sub-images into the main image. To synthesize. Since the overall configuration of the television receiver 10 of the present embodiment is the same as that of the television receiver 10 of the first embodiment shown in FIG. 2, the configuration and operation of the combining unit 36 will be described here. .
[0025]
The combining unit 36 includes a first combining unit 200, a conversion unit 210, a frame memory 212, and a second combining unit 202. The first synthesizing unit 200 synthesizes the sub-image layers B and C, and calculates an α value to be multiplied by the pixel value of the layer A that is the main image. First, α value α of layer B_BAnd the pixel value B from the color look-up table 100b or the like, and the α value α of the layer C_CAnd the pixel value C are read from the color look-up table 100c and the like. The pixel value B of layer B is multiplied by α_BIs multiplied by (1-α_C) Are respectively multiplied. The pixel value C of layer C is multiplied by α_CIs multiplied. These multiplication results are added by the adder 160, and the pixel value F of the composite layer F of the sub-image is calculated. That is, the pixel value F of the composite layer F is represented by the following expression.
F = α_B(1-α_C) B + α_CC
On the other hand, the first synthesizing unit 200 calculates an α value to be multiplied with the layer A as the main image. In this example, the multiplier 152 causes (1-α_B) (1-α_C) Is calculated.
[0026]
The pixel value F and α value calculated by the first synthesis unit 200 are output to the conversion unit 210. The conversion unit 210 performs predetermined processing on the sub-image synthesis layer F obtained by the first synthesis unit 200 to convert the image, and outputs the converted data to the frame memory 212. For example, the image size of the composite layer F of the sub image may be enlarged or reduced, or the number of bytes of the pixel value of the composite layer F may be changed. In this way, by combining the sub-images in advance, processing such as scaling and byte number conversion can be collectively performed on the entire sub-image.
[0027]
The frame memory 212 stores the sub image data F converted by the conversion unit 210 and the α value to be multiplied by the layer A. The second synthesis unit 202 reads the α value and the sub-image data F from the frame memory 212 in accordance with the stream of the image data A of the layer A, and synthesizes the layer A and the sub-image synthesis layer F. First, the multiplier 158 makes (1-α_B) (1-α_C) A is calculated, and the sub image data F is added to the calculation result by the adder 162 to obtain the pixel value E of the composite layer E.
[0028]
By combining a plurality of sub-images in advance and storing them in the frame memory 212, it is possible to reduce the number of computations from obtaining the layer A data stream to obtaining the synthesized layer E pixel values. Therefore, the delay time from the reception of the broadcast wave to the display of the video can be shortened. This is especially effective when the amount of data to be processed increases due to an increase in screen resolution or an increase in the number of pixel values in the future.
[0029]
(Third embodiment)
FIG. 8 shows an internal configuration of the combining unit of the television receiver according to the third embodiment. Similarly to the second embodiment, the synthesizing unit 36 of the present embodiment does not synthesize the sub-images to the main image one by one, but synthesizes a plurality of sub-images first, Then, the synthesized sub-image is synthesized with the main image. Since the overall configuration of the television receiver 10 of the present embodiment is the same as that of the television receiver 10 of the first embodiment shown in FIG. 2, the configuration and operation of the combining unit 36 will be described here. .
[0030]
In the synthesis unit 36 of the present embodiment, the circuit configuration of the first synthesis unit 200 in the synthesis unit 36 of the second embodiment illustrated in FIG. 7 is changed. In the second embodiment, α as layer B pixel data_BAnd B are input to the first combining unit 200. In the present embodiment, as in the first embodiment shown in FIG._BAnd α_BB is entered. That is, by using the color lookup table 102 shown in FIG._BSubstitute the calculation of × B by reading from the table. Thereby, the circuit configuration of the first synthesis unit 200 can be simplified, and the hardware configuration can be reduced. According to the experiments of the present inventors, it has been found that the circuit can be reduced by about 10% as compared with the conventional OSD. Other configurations and operations are the same as those in the second embodiment.
[0031]
(Fourth embodiment)
FIG. 9 shows an internal configuration of the combining unit of the television receiver according to the fourth embodiment. Since the overall configuration of the television receiver 10 of the present embodiment is the same as that of the television receiver 10 of the first embodiment shown in FIG. 2, the configuration and operation of the combining unit 36 will be described here. . Also in the present embodiment, as in the second and third embodiments, the sub-image is synthesized first, and finally, the sub-image synthesis layer is synthesized with the main image layer. Therefore, a case where one sub-image layer B is combined with the main image layer A will be described as an example.
[0032]
When the layer B index signal is input, the color lookup table 100b is referred to and α_BAnd B are output. Among the pixel values B, the luminance signal Y is used for the calculation as it is, but the color difference signals Cb and Cr generally include negative values. Therefore, prior to the calculation, the offset addition unit 220 adds the offset value to obtain a positive value. Convert to value. For example, when the color difference signals Cb and Cr can take values from −127 to +127, the offset adding unit 220 adds 128. The output (B + 128) of the offset adder 220 is multiplied by α by the multiplier 192._BIs multiplied by α_B(B + 128) is obtained. Here, in order to prevent a shift of an offset value, which will be described later, the offset adjustment unit 222 performs (1-α_B) × 128 is added. The output of the offset adjustment unit 222 is as follows.
α_B(B + 128) + (1-α_B) × 128 = α_BB + 128
The calculation result is input to the 444 → 422 conversion unit 224, and the color difference signals Cb and Cr are converted from 4 bytes to 2 bytes. Specifically, the number of bytes of the color difference signal is halved by substituting the color difference signal of the odd pixel with the color difference signal of the even pixel. The pixel value of the sub-image layer that is the output of the 444 → 422 conversion unit 224 and the α value to be multiplied by the main image layer A are stored in the frame memory 212.
[0033]
Similarly, 128 is added to the color difference signal of layer A, which is the main image, by the offset addition unit 226. The α value read from the frame memory 212 is multiplied by (A + 128) by the multiplier 194, and (1−α_B) (A + 128) is output. Here, in order to prevent a deviation of an offset value, which will be described later, the offset adjustment unit 228 (1-α_B) X 128 is subtracted. Output of the offset adjustment unit 228 (1-α_B) A and (α) read from the frame memory 212_BB + 128) is added by the adder 196, and (1-α_BA + α_BB + 128 is calculated.
[0034]
Here, the state of calculation when the offset adjusting units 222 and 228 are not provided will be described. FIG. 10 shows the pixel value of layer A, and FIG. 11 shows the pixel value and α value of layer B. Each of the four pixels shows a pixel value and an α value. The subscript indicates the layer type, and the superscript indicates the pixel number.
[0035]
FIG. 12 shows the calculation result output from the multiplier 192. For the luminance signal Y, an offset value is not added and α_BY is output, but the offset value is added to the color difference signals Cb and Cr, and α_B(Cb + 128) is output. FIG. 13 shows the calculation result output from the 444 → 422 conversion unit 224. The color difference signals Cb and Cr of the odd pixels are substituted by the color difference signals of the adjacent even pixels, and the number of bytes is halved.
[0036]
FIG. 14 shows the calculation result output from the multiplier 194. Read from the frame memory (1-α_B) Is multiplied by the pixel value of layer A. FIG. 15 shows the calculation result output from the adder 196. Although correct calculation results are obtained for the pixels 0 and 2 that are even pixels, the offset term is shifted for the pixels 1 and 3 that are odd pixels. Taking pixel 1 as an example, since the color difference signals Cb and Cr of the sub-image are substituted with the value of the adjacent pixel 0, α_B ⁰While the term of × 128 remains, the calculation of the main image layer A is α_B ¹Is used, so the offset term is α_B ¹The term x128 remains. α_B ⁰And α_B ¹If the two values are the same, these two terms cancel each other and no deviation occurs. However, if they are different values, the terms that should originally cancel each other remain and a deviation occurs.
[0037]
In order to solve such a problem, when the sub-image is synthesized, the offset adjustment unit 222 performs α_B ⁰Is canceled by the offset adjustment unit 228 when the main image is synthesized._B ¹Cancel the offset term containing. Thereby, the offset value can be prevented from shifting.
[0038]
FIG. 16 shows the calculation result output from the offset adjustment unit 222. In the offset adjustment unit 222, the calculation result of the multiplier 192 is (1−α_B) X 128 to add α_BThe offset term containing is canceled. FIG. 17 shows the calculation result output from the 444 → 422 conversion unit 224. The color difference signals Cb and Cr of the odd pixels are substituted with the color difference signals of the adjacent even pixels. FIG. 18 shows the calculation result output from the offset adjustment unit 228. The offset adjustment unit 228 calculates (1−α) from the calculation result of the multiplier 194._B) X 128 by subtracting α_BThe offset term containing is canceled. FIG. 19 shows the calculation result output from the adder 196. α_BSince the offset term including is canceled, the even value and the odd number of pixels are correct values with no offset value deviation.
[0039]
Here, the case where two images are combined has been described as an example. However, when three or more images are combined, the offset value can be similarly adjusted to prevent the pixel value from shifting. Further, in place of adjusting the offset term by the offset adjusting units 222 and 228, as for the α value, similarly to the color difference signal, the α value of the odd pixel is replaced with the α value of the even pixel, thereby shifting the offset value. Can be prevented.
[0040]
The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are within the scope of the present invention. . Such an example is described below.
[0041]
In the embodiment, two or three layers are combined, but the same applies to a case where more layers are combined. In the embodiment, the television receiver has been described as an example. However, the technology of the present invention can be used for all display devices having a function of displaying an image, such as a computer and a mobile phone.
[0042]
【The invention's effect】
According to the present invention, the hardware configuration of the image processing apparatus can be simplified.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of synthesis control between planes.
FIG. 2 is a diagram illustrating an overall configuration of a television receiver according to an embodiment.
FIG. 3 is a diagram for explaining a general configuration and operation of a combining unit.
4 is a diagram showing internal data of a color look-up table used in the synthesis unit shown in FIG. 3;
FIG. 5 is a diagram for explaining the configuration and operation of a combining unit according to the first embodiment.
6 is a diagram showing internal data of a color look-up table used in the synthesis unit shown in FIG.
FIG. 7 is a diagram for explaining the configuration and operation of a combining unit according to the second embodiment.
FIG. 8 is a diagram for explaining the configuration and operation of a combining unit according to a third embodiment.
FIG. 9 is a diagram for explaining the configuration and operation of a combining unit according to the fourth embodiment.
FIG. 10 is a diagram illustrating layer A pixel values;
FIG. 11 is a diagram illustrating layer B pixel values;
FIG. 12 is a diagram illustrating a calculation result output from a multiplier when offset adjustment is not performed.
FIG. 13 is a diagram illustrating a calculation result output from a 444 → 422 conversion unit when offset adjustment is not performed.
FIG. 14 is a diagram illustrating a calculation result output from a multiplier when offset adjustment is not performed.
FIG. 15 is a diagram illustrating a calculation result output from an adder when offset adjustment is not performed.
FIG. 16 is a diagram illustrating a calculation result output from an offset adjustment unit when offset adjustment is performed.
FIG. 17 is a diagram illustrating a calculation result output from a 444 → 422 conversion unit when offset adjustment is performed.
FIG. 18 is a diagram illustrating a calculation result output from an offset adjustment unit when offset adjustment is performed.
FIG. 19 is a diagram illustrating a calculation result output from an adder when offset adjustment is performed.
[Explanation of symbols]
10 television receiver, 32 video signal processing unit, 34 sub-image input unit, 36 synthesis unit, 100 color lookup table, 102 color lookup table, 200 first synthesis unit, 202 second synthesis unit, 210 conversion unit, 212 frame memory, 220 offset addition unit, 222 offset adjustment unit, 224 444 → 422 conversion unit, 226 offset addition unit, 228 offset adjustment unit.

Claims (1)

An image processing apparatus that mixes a main image that is a moving image or a still image plane and a plurality of sub-images that are subtitles or character graphic planes ,
A first combining unit that mixes the plurality of sub-images and calculates a mixing coefficient to be multiplied with the main image;
A conversion unit that performs scaling processing or byte number conversion processing on the mixed image mixed in the first combining unit;
A second combining unit for mixing the mixed image and the main image;
The first synthesis unit includes a table that holds a value obtained by multiplying a pixel value of a sub-image by a mixing coefficient and a mixing coefficient that is multiplied by the main image, and uses the values held in the table to mix the sub-image An image processing apparatus that performs calculation and outputs a mixing result of the plurality of sub-images and a mixing coefficient to be multiplied by the main image.

Images