Image enhancement processing apparatus and method

Claim 2

An apparatus according to claim 1, wherein said histogram distribution characteristics conversion means includes first gradation conversion means having gradation conversion characteristics for flattening the histogram distribution characteristics detected by said histogram distribution characteristics detection means; and second gradation conversion means having inverse gradation conversion characteristics to the gradation conversion characteristics for flattening the histogram distribution characteristics of the pixel values constituting an image represented by a reference image signal; and said first and second gradation conversion means are so arranged that the gradation of an image represented by an inputted arbitrary image signal is converted by said first gradation conversion means and then further converted by said second gradation conversion means.

Claim 3

An apparatus according to claim 2, wherein the image represented by said reference image signal is a standard image prepared in advance and having desired gradation characteristics.

Claim 4

An apparatus according to claim 2, further comprising display means for visually displaying an image represented by said reference image signal and an image of which histogram distribution characteristics are converted by said histogram distribution characteristics conversion means.

Claim 5

An apparatus according to claim 2, wherein the image represented by said reference image signal and the image represented by the image signal inputted into said histogram distribution characteristics detection means are radiation recording images obtained by irradiating a same portion of a same object or a same portion of objects of a same kind with a radiation and taking the image of the transmitted radiation.

Claim 6

An apparatus according to claim 1, wherein said histogram distribution characteristics conversion means includes first conversion memory table preparation means for preparing a first conversion memory table by preparing conversion data of gradation conversion characteristics for flattening the histogram distribution characteristics detected by said histogram distribution characteristics detection means and storing thus prepared conversion data in a memory table; histogram distribution characteristics generation means for generating the histogram distribution characteristics of pixel values constituting an image represented by the reference image signal; and second conversion memory table preparation means for preparing a second conversion memory table by preparing conversion data of gradation conversion characteristics inverse to the gradation conversion characteristics for flattening the histogram distribution characteristics generated in said histogram distribution characteristics generation means and storing thus prepared conversion data as memory table; and said means are so arranged that the gradation of an image represented by an inputted arbitrary image signal is converted by the first conversion memory table prepared by said first conversion memory table preparation means and further converted by the second conversion memory table prepared by said second conversion memory table preparation means.

Claim 7

An apparatus according to claim 6, wherein said histogram distribution characteristics detection means is adapted to detect the histogram characteristics from the pixel values of at least a part of the pixels constituting the image represented by the inputted image signal, and said histogram distribution characteristics generation means is adapted to generate the histogram characteristics from the pixel values of at least a part of the pixels constituting the reference image represented by the reference image signal.

Claim 8

An apparatus according to claim 1, wherein said histogram distribution characteristics conversion means includes first gradation conversion means adapted to prepare conversion data having gradation conversion characteristics for flattening the histogram distribution characteristics detected by said histogram distribution characteristics detection means, to convert, according to said prepared conversion data, the gradation of an image represented by an arbitrary image signal inputted into said histogram distribution characteristics detection means and to output the image with thus converted gradation, and second gradation conversion means adapted to select one of plural conversion memory tables respectively containing conversion data of gradation conversion characteristics inverse to the gradation conversion characteristics for flattening the histogram distribution characteristics of the pixel values constituting an image represented by an arbitrary image signal, to convert, according to the conversion data contained in the selected conversion memory table, the gradation of the image represented by the image signal outputted from said first gradation conversion means and to output the image with thus converted gradation.

Claim 9

An apparatus according to claim 1, further comprising a computer-readable memory medium storing a program for executing the processing operations in said histogram distribution characteristics detection means and said histogram distribution characteristics conversion means, wherein the processing operations are controlled by a computer functioning according to the program stored in said memory medium.

Claim 10

An image processing method capable of varying the gradation characteristics of an image, comprising: a) a histogram distribution characteristics detection step of detecting the histogram distribution characteristics of pixel values constituting an image represented by an inputted image signal; and b) a histogram distribution characteristics conversion step of converting the histogram characteristics detected by said histogram distribution characteristics detection step into arbitrary histogram distribution characteristics.

Claim 11

A method according to claim 10, wherein said histogram distribution characteristics conversion step includes a first gradation conversion step having gradation conversion characteristics for flattening the histogram distribution characteristics detected by said histogram distribution characteristics detection step; and a second gradation conversion step having inverse gradation conversion characteristics to the gradation conversion characteristics for flattening the histogram distribution characteristics of the pixel values constituting an image represented by a reference image signal; and said first and second gradation conversion steps are so arranged that the gradation of an image represented by an arbitrary image signal is converted by said first gradation conversion step and then further converted by said second gradation conversion step.

Claim 12

A method according to claim 11, wherein the image represented by said reference image signal is a standard image prepared in advance and having desired gradation characteristics.

Claim 13

A method according to claim 11, further comprising a display step of visually displaying an image represented by said reference image signal and an image of which histogram distribution characteristics are converted by said histogram distribution characteristics conversion step.

Claim 14

A method according to claim 11, wherein the image represented by said reference image signal and the image processed in said histogram distribution characteristics detection step are radiation recording images obtained by irradiating a same portion of a same object or a same portion of objects of a same kind with a radiation and taking the image of the transmitted radiation.

Claim 15

A method according to claim 10, wherein said histogram distribution characteristics conversion step includes a first conversion memory table preparation step of preparing a first conversion memory table by preparing conversion data of gradation conversion characteristics for flattening the histogram distribution characteristics detected by said histogram distribution characteristics detection step and storing thus prepared conversion data in a memory table; a histogram distribution characteristics generation step of generating the histogram distribution characteristics of pixel values constituting an image represented by the reference image signal; and a second conversion memory table preparation step of preparing a second conversion memory table by preparing conversion data of gradation conversion characteristics inverse to the gradation conversion characteristics for flattening the histogram distribution characteristics generated in said histogram distribution characteristics generation step and storing thus prepared conversion data as a memory table; and said means are so arranged that the gradation of an image represented by an arbitrary image signal is converted by the first conversion memory table prepared by said first conversion memory table preparation step and further converted by the second conversion memory table prepared by said second conversion memory table preparation step.

Claim 16

A method according to claim 15, wherein said histogram distribution characteristics detection step is adapted to detect the histogram characteristics from the pixel values of at least a part of the pixels constituting the image represented by the image signal, and said histogram distribution characteristics generation step is adapted to generate the histogram characteristics from the pixel values of at least a part of the pixels constituting the reference image represented by the reference image signal.

Claim 17

A method according to claim 10, wherein said histogram distribution characteristics conversion step includes a first gradation conversion step adapted to prepare conversion data having gradation conversion characteristics for flattening the histogram distribution characteristics detected by said histogram distribution characteristics detection step, to convert, according to said prepared conversion data, the gradation of an image represented by an arbitrary image signal, and a second gradation conversion step adapted to prepare plural conversion memory tables respectively containing conversion data of gradation conversion characteristics inverse to the gradation conversion characteristics for flattening the histogram distribution characteristics of the pixel values constituting an image represented by an arbitrary image signal, to select one of said plural conversion memory tables and to further effect, according to the conversion data contained in the selected conversion memory table, the gradation conversion of the image subjected to the gradation conversion in said first gradation conversion step.

Claim 18

A method according to claim 10, which comprises using a computer-readable memory medium storing a program for executing the processing operations in said histogram distribution characteristics detection step and said histogram distribution characteristics conversion step, and being executed by a computer functioning according to the program stored in said memory medium.

Claim 19

An image processing apparatus for processing plural images obtained under mutually different image taking conditions, comprising: a) differential image signal generation means for inputting plural image signals corresponding to plural images obtained under mutually different image taking conditions, and generating a differential image signal corresponding to a differential image of the images represented by the inputted plural image signals; and b) histogram distribution characteristics conversion means for inputting the differential image signal generated by said differential image signal generation means and converting the histogram distribution characteristics of the pixel values constituting the differential image represented by the inputted differential image signal into arbitrary histogram distribution characteristics.

Claim 20

An apparatus according to claim 19, wherein said differential image is a differential image of plural radiation images obtained by irradiating a same object with radiations of varied energy distributions and taking the transmitted image.

Claim 21

An apparatus according to claim 19, wherein said differential image is a differential image of plural radiation images obtained by irradiating a same object with a radiation and taking the transmitted images at mutually different timings.

Claim 22

An apparatus according to claim 19, wherein said arbitrary histogram distribution characteristics are histogram distribution characteristics of pixel values constituting any of plural images obtained under mutually different image taking conditions.

Claim 23

An apparatus according to claim 19, wherein said histogram distribution characteristics conversion means includes a conversion memory table storing conversion data for converting the histogram distribution characteristics.

Claim 24

An apparatus according to claim 23, wherein said conversion memory table includes a first conversion memory table for flattening the histogram distribution characteristics of pixel values constituting said differential image, and a conversion memory table storing conversion data of inverse conversion characteristics to the conversion characteristics stored in a second conversion memory table for flattening arbitrary histogram distribution characteristics.

Claim 25

An apparatus according to claim 19, further comprising a computer-readable memory medium storing a program for executing the processing operations in said differential image signal generation means and said histogram distribution characteristics conversion means, wherein the processing operations are controlled by a computer functioning according to the program stored in said memory medium.

Claim 26

An image processing method for processing plural images obtained under mutually different image taking conditions, comprising: a) a differential image signal generation step of inputting plural image signals corresponding to plural images obtained under mutually different image taking conditions, and generating a differential image signal corresponding to a differential image of the images represented by the inputted plural image signals; and b) a histogram distribution characteristics conversion step of inputting the differential image signal generated by said differential image signal generation step and converting the histogram distribution characteristics of the pixel values constituting the differential image represented by the inputted differential image signal into arbitrary histogram distribution characteristics.

Claim 27

A method according to claim 26, wherein said differential image is a differential image of plural radiation images obtained by irradiating a same object with radiations of varied energy distributions and taking the transmitted image.

Claim 28

A method according to claim 26, wherein said differential image is differential image of plural radiation images obtained by irradiating a same object with a radiation and taking the transmitted images at mutually different timings.

Claim 29

A method according to claim 26, wherein said arbitrary histogram distribution characteristics are histogram distribution characteristics of pixel values constituting any of plural images obtained under mutually different image taking conditions.

Claim 30

A method according to claim 26, wherein said histogram distribution characteristics conversion step is adapted to convert the histogram distribution characteristics of pixel values constituting the differential image represented by the inputted differential image signal into arbitrary histogram distribution characteristics, utilizing a conversion table storing conversion data for converting the histogram distribution characteristics.

Claim 31

A method according to claim 30, wherein said conversion table includes a first conversion table for flattening the histogram distribution characteristics of pixel values constituting said differential image, and a conversion table having inverse conversion characteristics to the conversion characteristics of a second conversion table for flattening arbitrary histogram distribution characteristics.

Claim 32

A method according to claim 26, which comprises using a computer-readable memory medium storing a program for executing the processing operations in said differential image signal generation step and said histogram distribution characteristics conversion step, and being executed by a computer, functioning according to the program stored in said memory medium.