JPH04268877A - Binary picture data encoding processor - Google Patents

Abstract

PURPOSE:To execute binary picture encoding with a high compression ratio by selecting a processing whose encoding efficiency is high at the time of MH encoding with picture data which is convolution-processed before the encoding pre-processing of binary picture data and picture data which is not convolution- processed in every main s can direction line. CONSTITUTION:A first convolution processing means 6-1 which executes the convolution processing of binary picture data is provided. A first exclusive OR processing means 13-1 which takes the exclusive OR of picture data of n-bits at every picture element, and first and second change point detection means 7-1 and 7-2 detecting the change point of picture data which is convolution-processed and picture data which is not convolution-processed are provided. A change point number comparison means 8 compares the number of the change points which the detection means 7-1 and 7-2 detect. A selection processing means 10 selects the processing of a side where the data compression rate becomes high at the time of encoding by using picture data which is convolution-processed and picture data which is not convolution-processed.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention is utilized for pre-encoding processing of binary image data. The present invention relates to a binary image data encoding processing device that performs pre-encoding processing on image data in which pseudo-halftone binary image data and simple binary image data are mixed.

0002

2. Description of the Related Art Conventionally, pre-encoding processing of this type of binary image data has been carried out using an n×n dither matrix (D
Taking advantage of the fact that the n-pixel image data has periodicity when binarized using the pixel matrix), the binary image data bit 12 is sequentially subjected to the exclusive-OR of n pixels by the exclusive OR processing unit 13. The process was repeated for each line in the main scanning direction. Such pre-encoding processing is called convolution processing.

As shown in FIG. 4, when convolution processing 15, which is pre-encoding processing, is performed on binary image data 14,
Pseudo-halftone image data binarized using an n×n dither matrix has a reduced number of changing points as data 16 after convolution processing, and therefore convolution processing is not performed during MH (Modified Huffman) encoding. High compression efficiency was obtained compared to image data without compression.

0004

[Problems to be Solved by the Invention] However, in the conventional pre-encoding processing of binary image data described above, the data is periodic every n pixels, such as data converted into pseudo halftone binary of a photographic image. This is an effective method only when the data has been converted into a binary value, such as a character image. increases, and there is a problem that data compression efficiency deteriorates during MH encoding when compared with binary image data that is not subjected to convolution.

[0005] Furthermore, in the case of an image containing a mixture of photographs and text, the binarized image data contains a mixture of pseudo-halftone image data and simple binary image data, and in this case, convolution processing is performed. However, although the number of change points decreases in the photograph part, the number of change points increases in the text part, which has the disadvantage that data compression efficiency cannot be improved during MH encoding.

The present invention solves these problems, and even when pseudo-halftone binary image data and simple binary image data are mixed, it is possible to improve the effect of convolution processing and achieve a high compression rate. The purpose of the present invention is to provide a device that can encode binary images.

[0007]

[Means for Solving the Problems] The present invention provides an A-D converter that converts an analog image signal into multi-value image data, and converts the multi-value image data into pseudo-halftone binary image data or simple binary image data. In a binary image data encoding processing device comprising a binarization processing section that converts into image data and an encoding section that encodes the converted image data, a binarized image from the binarization processing section is provided. First convolution processing means is provided for performing data convolution processing, and first exclusive OR processing is performed to perform exclusive OR of n-bit image data from the first convolution processing means pixel by pixel. means, first and second change point detection means for detecting a change point between the convolved image data and the unconvolved image data, and the first and second change point detection means detect the change point. A change point comparison means that compares the number of change points, and a process that increases the data compression rate when encoding using image data that has undergone convolution processing and image data that has not undergone convolution processing. The present invention is characterized by comprising a selective encoding pre-processing section including a selection processing means for selecting.

[0008] The selective encoding pre-processing section converts the mixed binary data from the binarization processing section, in which pseudo-halftone binary data and simple binary image data are mixed, into an image of one line in the main scanning direction. a line delay means for accumulating data; a second convolution processing means for convolving the binarized image data from the line delay means and sending the processed data to the selection processing means; a second exclusive OR processing means that performs an exclusive OR of n-bit image data from the second convolution processing means pixel-by-pixel, and two inputs of the selection processing means include the line delay The output of the means and the output of the second exclusive OR processing means are connected, and the selective encoding pre-processing section is configured to select a mode for determining which process is the selected process. It is preferable to include mode setting means for setting using additional bits.

[0009]

[Operation] When mixed binary image data containing photographs and text are received from the binarization processing unit, the data is stored as one line of image data in the main scanning direction, and is processed with the data to be convolved. The number of change points in one line in the main scanning direction is detected separately from the data that does not change, and it is determined whether the process has a large number of change points or the process has a small number of change points.

[0010] Next, the mode is set to the process with fewer determined change points, and the data is sent to undergo selection processing and MH encoding processing. When the processing mode for one line data is determined in this manner, the previously accumulated binary image data is divided into data that has been subjected to convolution processing and data that has not been subjected to convolution processing, and is then moved to selection processing. In the selection process, the data is sent to the MH encoding unit as data to be MH encoded according to the mode that has already been sent.

[0011] As a result, even in the case of image data in which pseudo-intermediate binary image data and simple binary image data are mixed, such as a mixed image of photographs and text, it is not affected by whether or not convolution processing is performed. A high compression rate can be obtained without any problems.

0012

Embodiments Next, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.
FIG. 2 is a diagram showing the configuration of the selective encoding preprocessing means according to the embodiment of the present invention.

The embodiment of the present invention includes an A-D converting section 2 that converts an image read by the scanner section 1 into multi-value image data, and converting the multi-value image data into pseudo-halftone binary image data 14,
Or a binarization processing unit 3 that converts into simple binary image data
and an MH encoding unit 5 that encodes the converted image data.
Further, as a feature of the present invention, a binarization processing section 3
A first convolution processing means 6-1 is provided which performs convolution processing 15 on the binary image data 14 from A first exclusive OR processing means 13-1 that takes an exclusive OR, and first and second change inspections that detect a change point between the convolved image data and the non-convolved image data. output means 7-1 and 7-2, and the first and second change point detection means 7
-1 and 7-2, the change point comparison means 8 compares the number of change points detected, and the data is encoded using the image data subjected to the convolution process and the image data not subjected to the convolution process. a selective encoding pre-processing unit 4 that includes a selection processing means 10 that selects a process that increases the compression rate;
Further, the selective encoding pre-processing unit 4 processes mixed binary data in which pseudo halftone binary data and simple binary image data are mixed from the binarization processing unit 3 in the main scanning direction. a line delay means 11 for accumulating line image data;
a second convolution processing means 6-2 that performs convolution processing on the binarized image data 14 from the line delay means 11 and sends the processed data to the selection processing means 10;
a second exclusive OR processing means 13-2 which performs an exclusive OR of the n-bit image data from the second convolution processing means 6-2 pixel by pixel;
The output of the line delay means 11 and the output of the second exclusive OR processing means 13-2 are connected to two inputs of the
Furthermore, the selective encoding preprocessing section 4 includes a mode setting means 9 that uses additional bits to set a mode for determining which process is the selected process.

The overall operation of the apparatus according to the embodiment of the present invention constructed as described above is such that the image read by the scanner section 1 is A-
The D converter 2 converts the data into multivalued image data. This multivalued image data is converted into pseudo-halftone binary image data or simple binary image data in the binarization processing section 3. The binarized image data is subjected to MH encoding in the MH encoding unit 5 after a selective encoding pre-processing unit 4 selects processing that improves compression efficiency during MH encoding.

Next, the operation of the selective encoding preprocessing section will be explained with reference to FIG.

When an image containing a mixture of photographs and text is binarized, pseudo-halftone binary image data and simple binary image data are mixed together. This mixed binary image data is accumulated by the line delay means 11 as one line of image data in the main scanning direction. On the other hand, the binary image data that is sent is
The first convolution processing means 6-1 divides the data into convolution-processed data and unprocessed data, and the first exclusive-OR processing means 13-1 performs an exclusive OR. The number of change points in one line in the main scanning direction of each data is detected by the change point detection means 7-1. Next, the change point comparing means 8 discriminates between processes with a large number of change points and processes with a small number of change points.

The mode of the determined process is set by the mode setting means 9 to the process with fewer change points, and the data of the mode is sent to the selection processing means 10 and the MH encoding section 5. When the processing mode for one line data is determined, the binary image data accumulated in the line delay means 11 is divided into data subjected to convolution processing by the second convolution processing means 6-2 and data not processed. and the selection processing means 10 via the second exclusive OR processing means 13-2.
sent to.

The selection processing means 10 receives the processing mode of the image data of this line from the mode setting means 9, and selects the data to be sent to the MH encoding section 5 according to the mode. From the mode setting means 9 to the MH encoding unit 5,
An additional bit is added to the beginning of the line to determine whether the binary image data of that line is convolution-processed data or unprocessed data.

[0019]

Effects of the Invention As explained above, according to the present invention, MH encoding can be performed using image data subjected to convolution processing in pre-encoding processing of binary image data and image data not subjected to convolution processing. By providing means for selecting processing that improves encoding efficiency for each line in the main scanning direction, it is possible to convert pseudo-halftone binary image data such as a mixed image of photographs and text to simple binary image data. Even in the case of mixed image data, it is possible to achieve a higher compression ratio than when performing convolution processing on all data, as in conventional pre-encoding processing, compared to when no convolution processing is performed. This has the advantage that value images can be encoded.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of selective encoding preprocessing means according to the embodiment of the present invention.

FIG. 3 is a block diagram illustrating convolution processing in a conventional example.

FIG. 4 is a diagram illustrating data in actual convolution processing.

[Explanation of symbols]

1 Scanner section 2 A-D conversion section 3 Binarization processing section 4 Selective encoding preprocessing section 5 MH encoding section 6-1 First convolution processing means 6-2 Second convolution processing means 7- 1 First change point detection means 7-2 Second change point detection means 8 Change point number comparison means 9 Mode setting means 10 Selection processing means 11 Line delay means 12 Binary image data bits 13 Exclusive OR processing section 13- 1 First exclusive OR processing means 13-2
Second exclusive OR processing means 14 Binary image data 15 Convolution processing

Claims (3)

[Claims] Claim 1: An A-D converter that converts an analog image signal into multivalued image data, and a binarization unit that converts the multivalued image data into pseudo-halftone binary image data or simple binary image data. In a binary image data encoding processing device that includes a processing section and an encoding section that encodes the converted image data, a step that performs a convolution process on the binary image data from the binarization processing section is provided. A convolution processing means is provided,
A first exclusive OR processing means that performs an exclusive OR of the n-bit image data from the first convolution processing means pixel by pixel, and the convolved image data and the unconvolved image data first and second change point detection means for detecting change points in image data; change point number comparison means for comparing the number of change points detected by the first and second change point detection means; and convolution processing. a selective encoding pre-processing section that includes a selection processing means for selecting a process that results in a higher data compression rate when encoding using image data that has undergone convolution processing and image data that has not undergone convolution processing; A binary image data encoding processing device characterized by: 2. The selective encoding pre-processing section converts the mixed binary data from the binarization processing section, in which pseudo-halftone binary data and simple binary image data are mixed, into one line in the main scanning direction. a second convolution processing means that performs convolution processing on the binarized image data from the line delay means and sends the processed data to the selection processing means; and a second exclusive OR processing means that performs exclusive OR of the n-bit image data from the second convolution processing means pixel by pixel, and the two inputs of the selection processing means include the 2. The binary image data encoding processing apparatus according to claim 1, wherein the output of the line delay means and the output of the second exclusive OR processing means are connected. 3. The binary code according to claim 2, wherein the selective encoding preprocessing unit includes mode setting means for setting a mode for determining which process is the selected process using additional bits. Image data encoding processing device.