JP2007036489A - Device and method for processing image data, and image-data processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the processing load on a device in the transfer of an image data. <P>SOLUTION: An input image data in a first color order by RGB from a PC is input to an image encoder 12, and the match or mismatch of a pixel value is predicted, while using an attentional pixel as a current processing object and the peripheral pixel of the target pixel as predictors in a predicting encoder 22 through an input 20. A counted value is used as a code under "a predicted-bit state" of the matching of the pixel value, and the differential value of the pixel value is used as the code under "a predicted miss state" of the mismatch of the pixel value, while color order is changed and encoded. Encoded data are output to an image decoder 14 via an output 24, decoded and output to an image output device 16. Since the color order is changed, when the image data are encoded in this manner, throughput can be reduced and the processing load is lightened. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image data processing device, an image data processing method, and an image data processing program, and converts image data having a first color order into image data having a second color order different from the first color order. The present invention relates to an image data processing device, an image data processing method, and an image data processing program.

  In recent years, with the spread of personal computers (hereinafter referred to as PCs) and the like, the conversion of electronic data into documents is becoming widespread, and the amount of data has increased to several times that in black and white with the rapid progress of colorization. Therefore, in order to reduce the data processing load on a colorized (multicolored) document, a color image compression coding method capable of high speed and high compression is desired.

  As image data representing a color image, there are known a dot sequential type and a frame sequential type. The dot-sequential image data includes, for example, R (red), G (green), B (blue), or Y (yellow), M (magenta), C (Sian), and K (black) color components. Treated together. Such dot-sequential image data is often used on a PC or the like because, for example, when image display is performed dot-sequentially on a CRT (Cathode Ray Tube), it can be displayed and output as it is and high-speed processing is possible. On the other hand, in the image data of the frame sequential method, each color component is individually handled, and is often used in, for example, a color printer using an electrophotographic technique. Therefore, it is necessary to convert dot sequential image data handled on a PC into frame sequential image data handled on a color printer.

In order to reduce the processing load and the conversion processing load, various techniques for encoding target image data with high speed and high compression have been proposed. For example, a technique for outputting color table data, resolution data, color order data, and run-length data from an encoding circuit as compression-encoded image data in order to compress and encode image data itself is known (for example, Patent Documents). 1). Further, when converting the image data of the dot-sequential method into the frame-sequential method, when performing a technique (for example, refer to Patent Document 2) that enables high-speed encoding / decoding, or when performing the data compression encoding, A technique (for example, see Patent Document 3) that promptly guarantees the data size has been proposed.
Japanese Patent Laid-Open No. 10-4498 JP 2002-335407 A JP 2004-32588 A

  However, when colorized image data is handled, the order of the colors depends on the application and apparatus configuration that handles the image data, and is not constant. Therefore, when colorized image data is exchanged, it is necessary to convert it to a color order determined by an application or apparatus that handles the colorized image data on either input / output side.

  For example, the color order specified on the output side of image data representing a color image may differ from the color order specified on the processing side that processes the image data. For example, the color order defined by an OS such as a PC is BGR, and an image processing apparatus such as a printer may want to process in RGB.

  As another case where the color order needs to be changed, in the case where the pixel value of one pixel can be expressed by one word or one double word, a plurality of components (components of color) can be expressed as a single internal integer of the CPU. Packing and handling is common. In this case, since the color order of image data output from CPUs having different byte orders is different, it is necessary to convert the color order in either the PC or the image processing apparatus.

  For this reason, in the above technique, the color order of the image data is converted in advance and then encoded (compressed), or the image data in which the color order is converted after decoding (decompression) is generated. For this reason, the processing amount required for the color order conversion is large, and the processing speed is reduced.

  In view of the above-described facts, an object of the present invention is to provide an image data processing apparatus, an image data processing method, and an image data processing program that can reduce the processing load of the apparatus in exchange of image data.

  In order to achieve the above object, an image data processing apparatus according to a first aspect of the present invention includes input means for inputting image data expressed in a dot sequential format according to a first color order, and pixel values of its own pixels and peripheral pixels. And encoding means for compressing the pixel values of a plurality of pixels in accordance with a predetermined condition while maintaining the first color order and encoding the encoded data into encoded data, and using the encoded encoded data as the predetermined condition. A decoding unit configured to decode the image data based on the image data, and the encoding unit or the decoding unit, wherein the color sequence of the plurality of colors is different from the first color sequence to the external device. Conversion means for converting to a second color order to be set; and output means for outputting image data of the second color order in the decoding means to an external device.

  The image data is expressed in a dot-sequential format according to the first color order and input to the input means. That is, the expression in the dot sequential format is a format in which each color component (pixel value) of a plurality of colors is handled together, and the image data has a pixel value for each color of the plurality of colors, and each pixel value is expressed as a first value. This is image data of an image having a plurality of pixels expressed by a data set of one color order.

  According to the first invention, the image data is encoded into the encoded data by compressing the pixel values of the plurality of pixels according to the predetermined condition while maintaining the first color order by the encoding means. This encoded data is decoded into image data by decoding means. In these encoding means or decoding means, the conversion means converts the color order of the plurality of colors from the first color order to the second color order. That is, the color order is converted at the time of encoding by the encoding means or at the time of decoding by the decoding means. As a result, the decoded image data has been converted into image data of the second color order, and this image data is output to the external device by the output means.

  Thus, since the color order of the image data is converted at the time of encoding by the encoding means or at the time of decoding by the decoding means, the color order is converted for the image data before encoding, or the image data after decoding is converted. Compared to changing the color order, the processing amount can be reduced, and the processing load can be reduced.

  The image data processing apparatus according to the second aspect of the invention is based on input means for inputting image data expressed in a dot-sequential format according to the first color order, and a plurality of pixels based on pixel values of its own pixels and peripheral pixels. Encoding means for compressing the pixel values of the pixels according to a predetermined condition while maintaining the first color order and encoding the encoded data into encoded data; and the encoded encoded data based on the predetermined condition Decoding means for decoding image data, grasping means for grasping the processing load of the encoding means and the processing load of the decoding means, grasping result of the grasping means, and the encoding based on the image data Or the decoding means is defined as a target means for converting from the first color order to a second color order different from the first color order and set in an external device, and in the determined target means, Multi-colored Conversion means for converting the order from the first color order to the second color order; and output means for outputting the image data of the second color order in the decoding means to an external device. .

  According to the second invention, the grasping means grasps the processing load of the encoding means and the processing load of the decoding means. Based on the grasp result and the image data, the conversion means determines either the encoding means or the decoding means as the target means for converting from the first color order to the second color order. In this conversion means, an encoding means or a decoding means with a small processing load on the image data can be determined. Then, the conversion means converts the color order of the plurality of colors in the determined target means.

  Thus, since the color order is converted in the encoding means or decoding means with the smaller processing load, the color order can be converted in the optimum means of the encoding means or decoding means, and the processing amount is reduced. In addition, the processing load can be reduced.

  The encoding means encodes, as a predetermined condition, encoded data of a count value in which the same pixel value continues for its own pixel and surrounding pixels, and a variation value of a different pixel value while maintaining the first color order. It is characterized by becoming.

  By doing in this way, about the pixel in which the same pixel value continues, it can compress to a count value and can be encoded into encoding data efficiently. In addition, regarding the pixels having different pixel values, by using the variation values, it is possible to set the pixels having a large pixel value to a smaller value than when the pixels are encoded as they are, and to efficiently encode the encoded data.

  In this case, the encoding means can encode the count value when the same pixel value continues for all the pixel values of the plurality of colors.

  By using the count value when the same pixel value continues for all the pixel values of a plurality of colors, it is possible to handle whether the code is a pixel unit, and the processing can be simplified.

  The image processing apparatus further includes setting means for detecting the first color order and the second color order and determining a correspondence relationship between the detected first color order and the second color order, and the conversion means includes the setting means The first color order is converted to the second color order according to the correspondence set in (1).

  A plurality of combinations of the first color order and the second color order are conceivable. Therefore, the first color order and the second color order are detected. Thereby, various color orders required for conversion can be grasped. The setting means determines a correspondence relationship between the detected first color order and the second color order. Thereby, it is possible to perform conversion in various color orders. In this case, a plurality of correspondence relationships between the first color order and the second color order are stored in the memory in advance, and the correspondence relationship between the detected first color order and the second color order is selected. Also good.

  Note that the processing load can be easily reduced by reducing the processing amount by the following image data processing method. Specifically, the present invention relates to an image data processing method in an image data processing apparatus having a function of converting image data expressed in a dot sequential format from a first color order to a second color order different from the first color order. Input image data of an image having a pixel value for each of a plurality of colors and each pixel value having a plurality of pixels represented by a data set according to a first color order, Based on the pixel values, the pixel values of a plurality of pixels are compressed according to a predetermined condition while maintaining the first color order and encoded into encoded data, and the encoded encoded data is encoded based on the predetermined condition. Decoding into the image data and converting the color order of a plurality of colors from the first color order to the second color order when the encoding or decoding is performed, and the decoded second color order Output image data to an external device.

  Further, by executing the next image data processing program on the computer, it is possible to easily achieve a reduction in processing load by reducing the amount of processing using the image data. Specifically, the image data processing program of the present invention inputs image data expressed in a dot-sequential format according to the first color order to a computer, and outputs a plurality of pixels based on pixel values of its own pixels and peripheral pixels. A pixel value is compressed according to a predetermined condition while maintaining the first color order and encoded into encoded data, and the encoded encoded data is decoded into the image data based on the predetermined condition, When encoding or decoding, the color order of a plurality of colors is converted from the first color order to a second color order different from the first color order and set in an external device, and the decoded The image data in the second color order is output to the external device.

  As described above, according to the present invention, since the color order of the image data is converted at the time of encoding by the encoding means or at the time of decoding by the decoding means, the color order of the image data before encoding can be converted. As compared with converting the color order of the image data after decoding, the processing amount can be reduced, and the processing load can be reduced.

  Hereinafter, embodiments of an image data processing device, an image data processing method, and an image data processing program of the present invention will be described in detail with reference to the drawings.

  FIG. 2 is an explanatory diagram showing the concept of image data expressed in a dot sequential format adopted in the following embodiments. In the image data in the dot sequential format shown in FIG. 2, the signal data of the R, G, and B color components are handled together for each pixel position. Therefore, for example, when storing image data, a set of R pixel value, G pixel value, and B pixel value representing the pixel is stored in a storage location corresponding to the pixel position.

  An image data processing apparatus and an image data processing program described in the following embodiments are used by being mounted on, for example, a color printer (image forming apparatus). That is, when image data expressed in the dot sequential format shown in FIG. 2 (hereinafter referred to as “input image data”) is received from a PC which is a host device, compression encoding is performed to reduce the amount of data, and the compressed code An image output device that performs decompression decoding on the converted image data (hereinafter referred to as “encoded data”), and includes the image data after the expansion decoding (hereinafter referred to as “decoded data”) in the color printer (Printer engine). In the following embodiment, the first color order is converted to the second color order at the time of compression encoding or decompression decoding. That is, since the input image data is expressed in the first color order specified by the OS such as a PC, the function of converting the input image data into image data expressed in the second color order specified on the color printer side. have.

  It should be noted that the image data need not be mounted on a color printer as long as the image data is encoded or decoded with color order conversion. For example, the image data may be mounted on a PC and used. Alternatively, it may be used by being mounted on another image output device such as a digital copying machine.

[First Embodiment]
In this embodiment, the color order is converted when the input image data is encoded.

  FIG. 1 is a block diagram showing a schematic configuration of a color printer 10 including an image data processing apparatus according to the present embodiment. The color printer 10 connected to the PC includes an image data processing device including an image encoding device 12 and an image decoding device 14, and an image output device 16. The image encoding device 12 includes an input unit 20 that receives input image data, a predictive encoding unit 22 and a color order conversion unit 26 that convert the input image data into encoded data, and an output unit 24 that outputs the encoded data. It is out. Input image data from the PC is connected to be output to the image decoding device 14 via the input unit 20, the prediction encoding unit 22, and the output unit 24 of the image encoding device 12. The predictive encoding unit 22 has a function of converting the color order while being encoded by the color order conversion unit 26 (details will be described later).

  The image decoding device 14 includes an input unit 30 that receives encoded data, a predictive decoding unit 32 that converts the encoded data into decoded data (details will be described later), and an output unit 34 that outputs the decoded data. Yes. The decoded data from the image encoding device 12 is connected so as to be output to the image output device 16 via the input unit 30, the predictive decoding unit 32, and the output unit 34 of the image decoding device 14.

  Here, the encoding process executed in the image encoding device 12 will be described. This encoding process is a process for executing a predictive encoding method for encoding while predicting the relationship between the target pixel and surrounding pixels for each pixel.

  As shown in FIG. 3, the encoding process uses a target pixel X that is currently processed, and a predictor B that represents a reference pixel and a predictor A that represents a prediction error calculation reference pixel as its surrounding pixels. In FIG. 3, the predictor A representing the prediction error calculation reference pixel is set as the pixel on the left side of the target pixel X.

  The encoding process (prediction) is performed by determining the coincidence of the pixel value of the target pixel X and the predictor (A or B). As a result of the determination, if the pixel values match, the “predicted hit state” is set, and if the pixel values do not match, the “predicted off state” is set.

  When the target pixel X is in the prediction hit state, the target pixel X is moved to the next adjacent pixel and the prediction is continued. As a result, while the “prediction hit state” continues, the identifier of the matched predictor and the number of times the prediction has been hit are obtained.

  On the other hand, when the pixel of interest X is in a mispredicted state, a prediction error is calculated as follows. The prediction error is calculated by calculating the difference between the pixel value of the predictor A that is the prediction error calculation reference pixel and the pixel value of the target pixel X that is the target pixel. This difference value is obtained as an error.

  The above encoding process will be specifically described.

  The arrangement of the predictors is as shown in FIG. In addition, as shown in FIG. 4, the code format 40 after the encoding process includes a symbol storage area 42 for storing a symbol indicating a prediction hit state or a prediction error state in which a prediction error has occurred, and a unique symbol format for each symbol. It consists of a symbol specific field 44 for storing data. The code format 40 is classified into a format 46 in a prediction hit state and a prediction error format 48 in a prediction error state.

  In the format 46 in the predicted hit state, a symbol representing the predicted hit state is stored in the symbol storage area 42, and the identifier of the predictor that matches and the number of times of matching (hit) are stored in the symbol specific field 44. In the format 48 in the case of an unpredicted state, a symbol representing an unpredicted state is stored in the symbol storage area 42, and the difference value of the predictor when there is a mismatch in the symbol specific field 44 is stored as an error.

  Since the mismatch is a pixel unit and an error is required for each color, as shown in FIG. 4, the error data of the prediction error is the number of image components n (for example, in the case of three colors of RGB) 3 components) error data of error values are stored.

  As an example, the operation of the encoding process will be described with reference to FIG. In FIG. 5, it is assumed that image data of an image composed of pixels having pixel values of three colors is composed of 3 pixels horizontally and 2 pixels vertically. An area (pixel value storage area) corresponding to each color included to express one pixel is referred to as a component. Further, in FIG. 5, it is assumed that the target pixel X is in a pixel indicated by hatching. The calculation formula for calculating the prediction error is such that the pixel value of the target pixel X is subtracted from the pixel value of the predictor A of the prediction error calculation reference pixel.

  First, when the prediction is performed, the pixel value (0, 1, 2) of the target pixel X matches the pixel value (0, 1, 2) of the predictor B, so that the predictor B is hit (the pixel values match). The predicted hit state. Next, when the target pixel X is moved to the pixel (1, 3, 5) on the right side and prediction is continued, a prediction hit state in which the predictor B is hit is obtained. Then, when the target pixel X is moved to the pixel (3, 4, 5) on the right and the prediction is continued, the pixel value (3, 4, 5) of the target pixel X and the pixel value (2, 3) and 4) are inconsistent, so the prediction is out of prediction. At this point, information on the predicted hit state so far is encoded.

  As the encoding result, the first encoded data of “symbol indicating prediction hit state, predictor B, twice” is obtained.

  In addition, since the prediction is out of order, a prediction error value is calculated. Since the predictor A of the prediction error reference pixel is a pixel on the left side of the target pixel X, the pixel value (3,4,5) of the target pixel X with respect to the pixel value (1,3,5) of the predictor A is calculated. Perform the operation and encode.

Prediction error = prediction error reference pixel (1, 3, 5) −target pixel (3,4,5)
= (-2, -1, 0)
As a result of encoding, second encoded data of “symbol indicating an unpredicted state, −2, −1, 0” is obtained.

  Next, the decoding process of encoded data will be described. Here, a process of decoding the encoded data obtained by encoding the image data shown in FIG. 5 as described above will be described.

The encoded data is
“Symbol indicating predicted hit state, predictor B, twice”
“Symbols indicating an unpredicted state, -2, -1, 0"
It is.

  By interpreting the encoded data, first, it is detected that the state is a prediction hit state, and it is understood that the predictor that has hit is the predictor B and the number of hits is two. Therefore, the pixel value of the predictor B is copied twice. In actual image data, (0, 1, 2) and (1, 3, 5) are copied.

  Next, it is detected that the prediction is off, and a prediction error (−2, −1, 0) is obtained.

In order to restore the pixel value, it is only necessary to perform a reverse calculation of the calculation rule when encoding. That is,
Prediction error = prediction error reference pixel−target pixel (pixel to be decoded)
Because
The target pixel (the pixel to be decoded) = prediction error reference pixel−can be restored by calculating the prediction error.

  Accordingly, (3, 4, 5) is obtained by subtracting (-2, -1, 0) from the prediction error reference pixel (1, 3, 5).

The decoding results calculated in this way are summarized as follows:
(0,1,2) (1,3,5) (3,4,5)
It can be understood that the pixel values are obtained and decoded correctly.

  Next, the operation of this embodiment will be described. In the present embodiment, when the input image data is encoded by the image encoding device 12, the color order of the image data is converted. In the following description, it is assumed that the color order of the image data output from the PC is RGB, and the image data is output to the image output device 16 in the BGR color order.

  FIG. 6 shows a flow of processing executed by the image encoding device 12. As shown in FIG. 6, first, in step 100, input image data from a PC is input. This input image data is in the first color order in RGB.

  In the next step 102, as described above, the state determination process of the encoding process is performed on one pixel of the image data input in step 100. That is, the target pixel X to be processed, the predictor B representing the reference pixel as the surrounding pixels, and the predictor A representing the prediction error calculation reference pixel, and the target pixel X and the predictor (A Alternatively, the pixel value of B) is determined to match, and as a result of the determination, one of the “predicted hit state” in which the pixel values match and the “prediction off state” in which the pixel values do not match is determined.

  In the case of the predicted hit state, the result is affirmative in step 102, and in step 104, the information on the predicted hit state is encoded as described above, and the process proceeds to step 106. In step 106, it is determined whether or not the image data has been encoded, that is, whether or not all pixels have been processed. If the determination is negative, the process returns to step 100 to repeat the process. If the determination in step 106 is affirmative, the encoded data is output from the output unit 24, and this routine is terminated.

  On the other hand, when the state is out of prediction, the result in Step 102 is negative, and the process proceeds to Step 110 to calculate a prediction error value. Next, after changing the color order in step 112, in step 114, information on the mispredicted state is encoded as described above.

Here, the processing of step 112 will be described in detail. In the case of a misprediction state, a color image composed of a plurality of components, that is, a multicolor image according to the present embodiment, performs prediction error calculation in the following RGB format.
(Prediction error calculation)
R error = R value of left pixel of target pixel-R value of target pixel G error = G value of left pixel of target pixel-G value of target pixel B error = B value of left pixel of target pixel-B of target pixel value

If the output is performed without changing the color order in accordance with the encoding format shown in FIG. 4, error values corresponding to RGB corresponding to the following components are obtained.
(Component RGB support)
First component error = R error Second component error = G error Third component error = B error

Accordingly, the output encoded data is as follows.
“Symbols that indicate an out-of-prediction state, R error, G error, and B error”
In the present embodiment, the color order conversion is performed by exchanging information on the misprediction state, that is, prediction error data. Note that it is assumed that the first pixel of the encoding process is in a mispredicted state.

That is, in order to convert the color order of the input image data, the position of the component may be changed. For example, when the color order is the BGR order, the following components correspond to BGR.
(Compatible with component BGR)
First component error = B error Second component error = G error Third component error = R error

Therefore, the encoded data in this case is as follows.
“Symbols that indicate an out-of-prediction state, B error, G error, R error”

  Therefore, in step 112, the color order is changed using a mapping that changes the correspondence of the error values of the components. Specifically, the color order RGB is mapped to the color order BGR for the input image data using the conversion table shown in FIG. By storing a plurality of conversion tables corresponding to the input / output color order and selecting the corresponding conversion table, it is possible to cope with various color order changes. In this way, the encoded data is converted into the second color order by BGR.

  In the example of FIG. 7, the color order RGB is mapped to the color order BGR, and the order of output components relative to the order of input components is used as a table. In other words, the output order (index) can be obtained by subtracting the conversion table using the input component number as an index.

  Specifically, the pseudo code is as follows.

(Pseudo code)
Out [1] = in [map [1]] = in [3];
Out [2] = in [map [2]] = in [2];
Out [3] = in [map [3]] = in [1];
However, Out [i] indicates the i-th component of the output, in [j] indicates the j-th component of the input, and map [k] indicates that the k-th index of the conversion table is referred to. .

To explain using specific pixel values, it is assumed that the input image data is an RGB image and the encoded data is encoded in the order of BGR.
First, the encoded data in the prediction hit state is not changed and becomes the next encoded data.
“Symbol indicating predicted hit state, predictor B, twice”

  Next, the prediction error at the time of the prediction error is (−2, −1, 0). Therefore, in order to change the color order, the order of output as output error values is obtained from the above conversion table, and the color order is converted. The result is as follows.

(Conversion result)
Output prediction error 1 = Third prediction error = 0
Output prediction error 2 = second prediction error = -1
Output prediction error 3 = first prediction error = -2
Therefore, the encoded data in the mispredicted state is the next encoded data.
“Symbols that indicate an unpredictable state, 0, −1, −2”

  As described above, according to the present embodiment, since the color order is changed when encoding image data, the processing amount can be reduced and the processing load can be reduced. More specifically, when the same pixel value continues, it can be compressed only to the count value, and the color order can be changed only by changing the storage position of the error value when the pixel values do not match. As a result, the processing load can be reduced as compared with the case where the color order is converted before or after the encoding in which the pixel values of all the pixels of the image data are calculated. Further, since the conversion process is performed in units of pixels, the processing load can be reduced as compared with the process that handles all the pixels constituting the image. Therefore, the processing time can be greatly shortened.

  In other words, by changing the color order when processing the prediction error in predictive coding, it is not necessary to change the color order for all pixel values, and the number of changes in the color order is limited to the time when the prediction error occurs. Therefore, high-speed processing becomes possible by reducing the number of changes.

[Second Embodiment]
In the present embodiment, the color order is converted when the encoded data is decoded. In addition, since this embodiment is a structure substantially the same as the said embodiment, the same code | symbol is attached | subjected to the same part and detailed description is abbreviate | omitted.

  FIG. 9 is a block diagram showing a schematic configuration of the color printer 10 including the image data processing apparatus according to the present embodiment. 9 is different from FIG. 1 in that the color order conversion unit 26 connected to the image encoding device 12 in FIG. 1 is unnecessary, and instead, the color order conversion unit 36 is connected to the image decoding device 14. Is a point. That is, the image encoding device 12 of this embodiment only converts input image data into encoded data, and the image decoding device 14 decodes the encoded data by the predictive decoding unit 32 and the color order conversion unit 36. When changing the color order.

  Next, the operation of this embodiment will be described. In this embodiment, the color order of image data is converted when the image decoding apparatus 14 decodes the encoded data.

  FIG. 10 shows a flow of processing executed by the image decoding device 14. As shown in FIG. 10, first, in step 200, encoded data from the image encoding device 12 is input. This encoded data is in the first color order in RGB.

  In the next step 202, the state determination process described above is performed by referring to the symbols for the encoded data input in step 200. That is, it is determined whether the symbol indicates a predicted hit state or a symbol that indicates an unpredicted state.

  The result is affirmative in step 202, and in step 204, the predicted hit state information is decoded as described above, and the process proceeds to step 206. Specifically, in the case of the predicted hit state, it is possible to grasp how many hits, that is, how many times the pixel value is matched with which predictor from the hit predictor and hit count data in the symbol specific field 44. Decoding is performed by copying the pixel value of the corresponding predictor (A or B) by the number of hits. In step 206, it is determined whether or not the decoding of the encoded data has been completed, that is, whether or not the decoding of the image data has been completed. If the determination is negative, the process returns to step 200 to repeat the process. If the determination in step 206 is affirmative, the decoded image data, that is, the decoded data is output from the output unit 34, and this routine is terminated.

  On the other hand, when the state is not predicted, the result in Step 202 is negative, and the process proceeds to Step 210. After the color order is changed, the pixel value is decoded as described above in Step 212 and output in Step 214.

  Here, the processing of step 210 will be described in detail. When an unpredicted state is detected in the encoded data, as described above, the prediction error values are arranged in the order of components following the symbol, and the prediction error value is calculated as the prediction error calculation reference pixel value and the prediction error value. By doing so, the pixel value can be decoded. Since decoding is the reverse of encoding, the following decoding calculation is performed.

(Decryption calculation)
Pixel value of first component = component value of left pixel−first error value pixel value of second component = component value of left pixel−second error value pixel value of third component = component value of left pixel−third error Value (decoding calculation for RGB)
R value of the pixel to be decoded = R value of the left pixel of the pixel to be decoded-R error G value of the pixel to be decoded = G value of the left pixel of the pixel to be decoded-G error B value of the pixel to be decoded = Left of the pixel to be decoded Pixel B value-B error

When decoding is performed without changing the color order in accordance with the encoding format shown in FIG. 4, the pixel values corresponding to RGB corresponding to the following components are obtained.
(Component RGB support)
1st component value = R value 2nd component value = G value 3rd component value = B value

Accordingly, the output decoded data is as follows.
(R value, G value, B value)

In the present embodiment, when the mispredicted state is detected, the decoded data is exchanged to correspond to the color order conversion. That is, in order to convert the color order, the output position of the component may be changed. For example, when decoding the encoded data encoded in the RGB color order into the decoded data in the BGR color order, the following components are supported for decoding.
(Component decryption support)
First component value = B pixel value Second component value = G pixel value Third component value = R pixel value

  Therefore, in step 210, the color order is changed using a mapping that changes the correspondence of the output of the component. Specifically, the color order RGB is mapped to the color order BGR for the encoded data using the conversion table shown in FIG. By storing a plurality of conversion tables corresponding to the input / output color order and selecting the corresponding conversion table, it is possible to cope with various color order changes. In this way, the encoded data is converted into the second color order by BGR.

  The example of FIG. 7 maps the output of the encoded data of the color order RGB to the decoded data of the color order BGR, and uses the order of the output components relative to the order of the input components as a table. In other words, an output order (index) can be obtained by subtracting a conversion table using an input component number as encoded data as an index.

  Specifically, the pseudo code is as follows.

(Decryption pseudo code)
First error value = error code string [map [1]];
Second error value = error code string [map [2]];
Third error value = error code string [map [3]];
Here, map [m] indicates that the mth index of the conversion table is referred to.

  This will be specifically described. Here, it is assumed that the encoded data is a BGR image and the decoded data is decoded so as to be in RGB order. The result is as follows.

First error value = R error value = error code string [map [1]] = third error code second error value = G error value = error code string [map [2]] = second error code Error value = B error value = error code string [map [3]] = first error code

  Next, calculation for decoding is performed as follows.

First component pixel value = left pixel R value−R error value second component pixel value = left pixel G value−G error value third component pixel value = left pixel B value−B error value Decoded data in color order can be obtained.

Next, numerically, the encoded data at the time of the mispredicted state is
“Symbols that indicate an unpredictable state, 0, −1, −2”
Encoded data.

Therefore, the order of the prediction error values (0, -1, -2) is changed as described above. That is, according to the definition of FIG. 8, the following result is obtained.
First error value = R error value = third error code = −2
Second error value = G error value = second error code = −1
Third error value = B error value = 1st error code = 0

Since the pixel value of the decoding result is a difference from the prediction error reference pixel, it can be obtained as follows, and the decoding result (3, 4, 5) is obtained.
First component pixel value = left pixel R value (1) −R error value (−2) = 3
Second component pixel value = left pixel G value (3) −G error value (−1) = 4
Third component pixel value = left pixel B value (5) −B error value (0) = 5

  As described above, according to the present embodiment, since the color order is changed when decoding image data, the processing amount can be reduced and the processing load can be reduced as in the above-described embodiment. be able to.

  That is, by changing the color order when manipulating the prediction error in decoding of the prediction code, it is not necessary to change the color order for all the pixel values, and the number of times the color order is changed only when a prediction error occurs. Since the number of changes can be reduced, the number of changes can be reduced, thereby enabling high-speed processing.

[Third Embodiment]
In this embodiment, the color order is converted when the input image data is encoded or when the encoded data is decoded. In addition, since this embodiment is a structure substantially the same as the said embodiment, the same code | symbol is attached | subjected to the same part and detailed description is abbreviate | omitted.

  FIG. 11 is a block diagram showing a schematic configuration of the color printer 10 including the image data processing apparatus according to the present embodiment. 11 differs from FIG. 1 and FIG. 9 in that the color order conversion unit 26 and the color order conversion unit 36 use the image encoding device 12 in FIG. 1 and the image decoding device 14 in FIG. 18 is connected. The determination unit 18 is connected so that image data is input from the PC. In the present embodiment, any one of the image encoding device 12 and the image decoding device 14 is determined as a target portion whose color order is to be converted, and the color order is converted in the corresponding device.

  Next, the operation of this embodiment will be described. The operations of the image encoding device 12 and the image decoding device 14 are the same as described above, and thus detailed description thereof is omitted.

  FIG. 12 shows the flow of processing executed by the determination unit 18 of this embodiment. As shown in FIG. 12, first, the load on the image encoding device 12 is detected in Step 300, and the load on the image decoding device 14 is detected in the next Step 302. The load detected in step 300 and step 302 is stored in advance that represents the capacity of the software resource as the standard processing time of the data or the pre-stored data representing the capacity of the hardware resource such as the CPU capacity and storage capacity of each device. There is data. In the next step 304, image data from the PC is read. The image data read in step 304 is data related to the load such as the capacity and format of the image data.

  In the next step 306, using the data obtained in steps 300 to 304, either the image encoding device 12 or the image decoding device 14 is determined as a color order conversion target device. In this determination, when processing the image data in step 304, it is possible to determine a device with a low processing load, for example, a device with a fast CPU capability, a device with a large storage capacity, and a device with software with a short processing time.

  When the target device for color order conversion is determined in step 306, the color order conversion processing is performed on the corresponding device (the prediction encoding unit 22 and the color order conversion unit 26 of the image encoding device 12 or the prediction decoding of the image decoding device 14). The determination unit 18 outputs a control signal for processing by the conversion unit 32 and the color order conversion unit 36). Accordingly, either the image encoding device 12 or the image decoding device 14 is operated as a target device that executes the color order conversion process.

  As described above, according to the present embodiment, the apparatus can be selected according to the load situation when the color order is converted, so that the color order conversion can be quickly performed in accordance with the image data and the additional situation of the apparatus. Can be processed.

1 is a block diagram showing a schematic configuration of an image data processing apparatus according to a first embodiment of the present invention. It is explanatory drawing which shows the concept of the image data expressed by a dot sequential format. It is a schematic diagram which shows the relationship of the attention pixel and its surrounding pixel in an encoding process. It is a conceptual diagram which shows the code format of an encoding process. It is an image figure which shows the example of arrangement | positioning of the pixel which comprises an image. It is a flowchart which shows the flow of the process performed with the image coding apparatus concerning 1st Embodiment of this invention. It is a conceptual diagram which shows the conversion table utilized when changing a color order in an image coding apparatus. It is a conceptual diagram which shows the conversion table utilized when changing a color order in an image decoding apparatus. It is a block diagram which shows schematic structure of the image data processing apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the flow of the process performed with the image decoding apparatus concerning 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the image data processing apparatus which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the flow of the process performed by the determination part of the color printer concerning 3rd Embodiment of this invention.

Explanation of symbols

A ... Predictor B ... Predictor X ... Pixel 10 of interest ... Color printer 12 ... Image encoding device 14 ... Image decoding device 16 ... Image output device 18 ... Determining unit 20 ... Input unit 22 ... Predictive encoding unit 24 ... Output Unit 26 ... Color order conversion unit 30 ... Input unit 32 ... Predictive decoding unit 34 ... Output unit 36 ... Color order conversion unit 40 ... Code format 42 ... Symbol storage area 44 ... Symbol specific field 46 ... Format 48 ... Format

Claims (7)

Input means for inputting image data expressed in a dot-sequential format according to a first color order;
Encoding means for compressing the pixel values of a plurality of pixels based on the pixel values of the self pixel and the surrounding pixels according to a predetermined condition while maintaining the first color order and encoding the encoded data into encoded data;
Decoding means for decoding the encoded data into the image data based on the predetermined condition;
In the encoding means or the decoding means, conversion means for converting the color order of a plurality of colors from the first color order to a second color order that is different from the first color order and is set in an external device. When,
Output means for outputting image data of the second color order in the decoding means to an external device;
An image data processing apparatus. Input means for inputting image data expressed in a dot-sequential format according to a first color order;
Encoding means for compressing the pixel values of a plurality of pixels based on the pixel values of the self pixel and the surrounding pixels according to a predetermined condition while maintaining the first color order and encoding the encoded data into encoded data;
Decoding means for decoding the encoded data into the image data based on the predetermined condition;
Grasping means for grasping the processing load of the encoding means and the processing load of the decoding means;
Based on the grasping result of the grasping means and the image data, the encoding means or the decoding means differs from the first color order from the first color order and is set in an external device. Conversion means for converting the color order of a plurality of colors from the first color order to the second color order in the determined target means,
Output means for outputting image data of the second color order in the decoding means to an external device;
An image data processing apparatus.   The encoding means encodes, as a predetermined condition, encoded data of a count value in which the same pixel value continues for its own pixel and surrounding pixels, and a variation value of a different pixel value while maintaining the first color order. The image data processing apparatus according to claim 1, wherein the image data processing apparatus is an image data processing apparatus.   The image data processing apparatus according to claim 3, wherein the encoding unit encodes a count value when the same pixel value continues for all pixel values of the plurality of colors. Setting means for detecting the first color order and the second color order and determining a correspondence relationship between the detected first color order and the second color order;
5. The conversion device according to claim 1, wherein the conversion unit converts the first color order into the second color order according to the correspondence set by the setting unit. 6. Image data processing device. An image data processing method in an image data processing apparatus having a function of converting image data expressed in a dot-sequential format from a first color order to a second color order different from the first color order,
Input image data expressed in a dot-sequential format according to the first color order;
Based on the pixel values of its own pixels and surrounding pixels, the pixel values of a plurality of pixels are compressed according to a predetermined condition while maintaining the first color order and encoded into encoded data,
Decoding the encoded data into the image data based on the predetermined condition;
Converting the color order of a plurality of colors from the first color order to the second color order when encoding or decoding;
An image data processing method for outputting the decoded image data of the second color order to an external device. On the computer,
Input image data expressed in a dot-sequential format according to the first color order;
Based on the pixel values of its own pixels and surrounding pixels, the pixel values of a plurality of pixels are compressed according to a predetermined condition while maintaining the first color order and encoded into encoded data,
Decoding the encoded data into the image data based on the predetermined condition;
Converting a color order of a plurality of colors when encoding or decoding from the first color order to a second color order different from the first color order and set in an external device;
An image data processing program for outputting the decoded image data of the second color order to an external device.

Images