Image processing apparatus and method, and recording medium therefor
First Claim
1. An image processing apparatus for correcting the gray level of an image signal, comprising:
- first generating means for generating a first conversion rule by using a first element of the image signal that has been input;
second generating means for generating a second conversion rule on the basis of the first conversion rule;
first correcting means for correcting the first element of the input image signal by using the first conversion rule;
acquiring means for acquiring a correction parameter associated with the first element of the input image signal by using the second conversion rule; and
second correcting means for correcting a second element of the input image signal by using the correction parameter.
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Abstract
An image processing apparatus and method and a recording medium therefor control the occurrence of a change in a hue. The histogram of a luminance signal Y is generated in a first step S1. In a second step S2, the histograms of the luminance signals Y are accumulated to generate a cumulative histogram, and the cumulative histogram is subjected to logarithmic approximation thereby to generate a lookup table (LUT) for correcting luminance signals. In a third step S3, a color-difference signal correction parameter LUT is generated by referring to the LUT for correcting luminance signals. In a fourth step S4, an input luminance signal Y is applied to the LUT for correcting luminance signals thereby to acquire a corrected luminance signal Y0. In a fifth step S5, the input luminance signal Y is applied to a color-difference signal correction parameter LUT so as to acquire a correction parameter k. In a sixth step S6, input color-difference signals Cr and Cb are multiplied by the correction parameter k to acquire corrected color-difference signals Cr0 and Cb0.
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Citations
27 Claims
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1. An image processing apparatus for correcting the gray level of an image signal, comprising:
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first generating means for generating a first conversion rule by using a first element of the image signal that has been input;
second generating means for generating a second conversion rule on the basis of the first conversion rule;
first correcting means for correcting the first element of the input image signal by using the first conversion rule;
acquiring means for acquiring a correction parameter associated with the first element of the input image signal by using the second conversion rule; and
second correcting means for correcting a second element of the input image signal by using the correction parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An image processing method for an image processing apparatus for correcting the gray level of an image signal, the image processing method comprising:
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a first generating step for generating a first conversion rule by using a first element of the image signal that has been input;
a second generating step for generating a second conversion rule on the basis of the first conversion rule;
a first correcting step for correcting the first element of the input image signal by using the first conversion rule;
an acquiring step for acquiring a correction parameter associated with the first element of the input image signal by using the second conversion rule; and
a second correcting step for correcting a second element of the input image signal by using the correction parameter. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27)
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19. A recording medium in which a computer-readable image processing program for correcting the gray level of an image signal has been recorded, the program comprising:
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a first generating step for generating a first conversion rule by using a first element of the image signal that has been input;
a second generating step for generating a second conversion rule on the basis of the first conversion rule;
a first correcting step for correcting the first element of the input image signal by using the first conversion rule;
an acquiring step for acquiring a correction parameter associated with the first element of the input image signal by using the second conversion rule; and
a second correcting step for correcting a second element of the input image signal by using the correction parameter.
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Specification