JPH0630246A - Summary image generating system - Google Patents

Abstract

PURPOSE:To suppress the loss of the feature of an original image even with a small amount of data by outputting multigradation image data to which thinning-out and reduction are applied from an output table by converting into a summary image. CONSTITUTION:An image data input part inputs two-dimensional multigradation image data, and supplies it to a thinning-out/reduction part 20. The reduction part 20 stores inputted data in image memory 21 in two-dimensional fashion, and it is controlled by an image memory controller 22, then, it is written on the memory 21. The data is thinned-out by supplying an address thinned-out by the controller 22 and reading out. The histogram of the multigradation image data to which the thinning-out and reduction are applied is generated by a histogram generation and uniformalization part, and also, it is uniformalized. The output table is set based on such uniformalized histogram, and the multigradation image data is converted into the summary image corresponding to the frequency distribution of reduction image data. Thereby, it is possible to suppress the loss of the feature of the original image even with a small amount of data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a summary image creating method, and more particularly to a summary image creating method for creating a summary image from a two-dimensional multi-tone image.

[0002]

2. Description of the Related Art In a conventional summary image forming method, as shown in FIG.
The data amount is reduced by thinning and reducing by 0 and truncating the lower bits by the lower bit truncating unit 80 to obtain a summary image.

[0003]

In the above-mentioned conventional summary image creating method, since the lower bits of the multi-tone image data are uniformly cut off, it is not always possible to obtain a summary image with less loss of characteristics of the original image. There was a problem that it was not limited.

An object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to provide a summary image forming system in which the loss of the characteristics of the original image is significantly suppressed even with a small amount of data.

[0005]

The method of the present invention is a summary image creating method for creating a summary image from two-dimensional multi-tone image data, in which the multi-tone image data is input.
A thinning reduction means for performing a thinning reduction including an average reduction or an interpolation reduction and a histogram showing the appearance frequency of each gradation of the multi-tone image data thinned and reduced by the thinning reduction means are created, and Histogram creating / equalizing means for equalizing, output table setting means for setting the output table required for summary image output based on the equalized histogram in correspondence with the gradation characteristics of the original image, and the thinning-down reducing means And a summary image output means for converting the multi-tone image data thinned and reduced by the output table into a summary image and outputting the summary image.

According to the method of the present invention, in the summary image creating method for creating a summary image from two-dimensional multi-tone image data, the multi-tone image data is input and thinning out including average reduction or interpolation reduction is performed. Decimation / reduction means for performing demagnification, and a look-up table for setting up a look-up table showing conversion contents for performing gradation conversion corresponding to the gradation characteristic of the original image on the thinned-down multi-tone image data The configuration includes a setting means and a summary image output means for performing gradation conversion on the multi-gradation image data based on the look-up table and outputting as a summary image.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 1 shows an image data input unit 1 which constitutes thinning reduction means for performing thinning reduction on input multi-tone image data.
0 and thinning reduction unit 20 and a histogram showing the appearance frequency of each gradation of thinned-down multi-tone image data and equalizing this histogram creating / equalizing histogram forming equalizing means The conversion unit 30 includes an output table setting unit 40 that configures an output table setting unit that sets an output table necessary for creating a summary image, and a summary image output unit 50a that configures the summary image output unit.

Next, the operation of the first embodiment will be described.

The image data input unit 10 inputs the two-dimensional multi-tone image data and supplies it to the thinning and reducing unit 20.

As shown in FIG. 2, the thinning and reducing section 20 includes an image memory 21 for two-dimensionally storing the input multi-tone image data and an image memory controller 22 for controlling writing and reading to and from the image memory 21. The multi-tone image data input by the image data input unit 10 is written two-dimensionally in the image memory 21 under the control of the image memory controller 22. The written multi-tone image data is thinned by being read by being given an address thinned by the image memory controller 22.

The thinned and reduced multi-tone image data is then used for histogram creation by the histogram creation / equalization unit 30, and the created histogram is subjected to equalization.

FIG. 3 shows the histogram (a), the equalized histogram (b) and the output table (c) created from the equalized histogram in the first embodiment of FIG.

The image data thinned and reduced by the thinning and reducing unit 20 is supplied to the histogram creating / equalizing unit 30 and counted for each data to create the histogram shown in FIG. 3 (a).

Next, the total number of the thinned and reduced image data is divided by the number of gradations for the summary image to determine the number of allocated image data per gradation. The histograms are equalized by grouping the image data according to the number of assigned image data. The equalized histogram thus obtained is shown in FIG. The output table shown in FIG. 3C is set based on this equalized histogram.

The output table set in this way can output more detailed (finer) gradation differences as the number of appearance frequencies increases in the histogram before equalization.

The image data thinned and reduced by the thinning and reducing unit 20 is converted into a summary image by the summary image output unit 50a by this output table and is output.

Since the summary image conversion of the thinned-down image data by this output table is performed corresponding to the frequency distribution of the thinned-down image data, it is possible to secure the summary image in which the characteristic loss of the original image is significantly suppressed.

FIG. 4 is a block diagram of the second embodiment of the present invention. The second embodiment is different in that the thinning-out reduction of the first embodiment shown in FIG. 1 is based on the average reduction, and the other components are almost the same, so a detailed description of these same contents will be given. Is omitted.

FIG. 4 shows the thinning-out reducing unit 20 of the second embodiment.
The structure of a is shown, and it corresponds to the image memory 21 that stores the input multi-tone image two-dimensionally, the image memory 23 that controls writing and reading to and from the image memory 21, and the reduction ratio when performing the average reduction. And a mean value calculator 24 for calculating a mean place.

Under the control of the image memory controller 23, the average value calculator 24 calculates the average value of the image data read from the image memory 21 in accordance with the reduction rate.

For example, in the case of ½ reduction, the average value of the data of the 2 × 2 matrix, and in the case of ⅓ reduction, it is 3 × 3.
The average value of the matrix data becomes the reduced data.

FIG. 5 is a block diagram of the third embodiment of the present invention. The third embodiment is different in that the first thinning reduction shown in FIG. 1 is based on interpolation reduction, and other components are almost the same, so detailed description regarding these same contents will be omitted.

In FIG. 5, the image data read from the image memory 31 under the control of the image memory controller 22 is interpolated and reduced by the interpolating calculator 24 to become interpolated reduced data.

FIG. 6 is a block diagram of the fourth embodiment of the present invention. In the fourth embodiment shown in FIG. 6, a summary image is obtained by performing an image data input unit 10, a thinning reduction unit 20 for thinning down the input image data, and a gradation conversion of the thinned down image data. A lookup table setting unit 60 that sets a lookup table to be created and a summary image output unit 50b that outputs a summary image using the lookup table are provided.

FIG. 7 shows an example of setting a look-up table by the look-up table setting unit 60 of FIG. The image data input to the image data input unit 10 is thinned and reduced by the thinning and reducing unit 20 in the same manner as in the first embodiment shown in FIG. The image data that has been thinned out and reduced is
Grayscale conversion is performed in consideration of the grayscale characteristics of the original image using a look-up table and converted into a summary image, which is output from the summary image output unit 50b.

Since the summary image conversion process of the thinned-down image data by the look-up table described above is performed according to the gradation characteristics of the thinned-down image data, a summary image with less loss of the original image features can be obtained.

It is to be noted that the thinning reduction unit 20a shown in FIG. 4 averages the thinning reduction unit 20 shown in FIG. 6 in the fifth embodiment, and the thinning reduction unit 20b shown in FIG. The reduction is the sixth embodiment of the present embodiment.

[0029]

As described above, the present invention is based on an output table or a look-up table which is set in consideration of the gradation characteristics of an original image. By performing the summary image conversion of the data, it is possible to obtain a summary image creation method in which the loss of the original image is significantly suppressed even with a small amount of data.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram of a thinning and reducing unit 20 of FIG.

3 is a histogram (a), an equalized histogram (b) and an output table (c) in the embodiment of FIG.

FIG. 4 is a block diagram of a second embodiment of the present invention.

FIG. 5 is a block diagram of a third embodiment of the present invention.

FIG. 6 is a block diagram of a fourth embodiment of the present invention.

7 is a diagram showing an example of characteristics of the lookup table of FIG.

FIG. 8 is a block diagram of a conventional summary image creating method.

[Explanation of symbols]

 10 image data input unit 20, 20a, 20b thinning reduction unit 21 image memory 22, 23 image memory controller 14 average value calculator 30 histogram creation / equalization unit 40 output table setting unit 50a, 50b summary image output unit 60 lookup Table setting unit 70 Thinning reduction unit 80 Lower bit truncation unit

Claims (2)

[Claims] 1. A summary image creating method for creating a summary image from two-dimensional multi-tone image data, in which the multi-tone image data is input, and thinning-down is performed to perform thinning-down including average reduction or interpolation reduction. Means and a histogram showing the appearance frequency for each gradation of the multi-gradation image data thinned and reduced by the thinning and reducing means,
And a histogram creating / equalizing means for equalizing the same, an output table setting means for setting an output table necessary for summary image output based on the equalized histogram in correspondence with the gradation characteristic of the original image, And a summary image output means for converting the multi-tone image data thinned and reduced by the thinning and reducing means into a summary image by the output table and outputting the summary image. 2. A summary image creating method for creating a summary image from two-dimensional multi-tone image data, in which the multi-tone image data is input, and thinning-down is performed to perform thinning-down including average reduction or interpolation reduction. Means, lookup table setting means for setting a lookup table indicating conversion contents for performing gradation conversion corresponding to the gradation characteristics of the original image on the thinned-down multi-gradation image data, And a summary image output means for performing gradation conversion on the multi-gradation image data based on a look-up table and outputting as a summary image.