Image gradation correction based on switching resolution of correction coefficients
AssigneeSony Corporation
InventorsMasami Ogata, Takashi Tsuchiya, Kazuhiko Ueda
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Abstract
The invention provides an image processing apparatus and an image processing method. An area to which image data belongs is discriminated, and a correction coefficient to be used for correction of a pixel value of the image data is produced based on a result of the discrimination. Then, the pixel value of the image data is corrected with the correction coefficient. The relationship in magnitude among pixel values in the same area is maintained because the same coefficient is used, but pixel values which belong to different areas can be varied or even reversed. This allows the gradation of an entire image to be corrected while preventing partial deterioration of the contrast.
Claims30
An image processing apparatus capable of correcting the gradation of image data, comprising:
- area discrimination means for discriminating areas to which the image data belong and outputting discrimination results;
- coefficient calculation means for outputting correction coefficients to be used for correction of pixel values of the image data based on the discrimination results;
- and
- correction means for correcting the pixel values of the image data with the correction coefficients;
- the area discrimination means or the coefficient calculation means producing the discrimination results or the correction coefficients so as to switch a resolution of the correction coefficients in response to the pixel values of the image data;
- wherein
- the coefficient calculation means sets the correction coefficients at a fixed value when a signal level of the discrimination results is less than or equal to a prescribed value, and the coefficient calculation means sets the correction coefficients at a value less than the fixed value when the signal level of the discrimination results is greater than the prescribed value.
An image processing method for correcting the gradation of image data, comprising:
- discriminating areas to which the image data belong and outputting discrimination results;
- outputting correction coefficients to be used for correction of pixel values of the image data based on the discrimination results;
- and
- correcting the pixel values of the image data with the correction coefficients in an image processing apparatus;
- the discrimination results or the correction coefficients switching a resolution of the correction coefficients in response to the pixel values of the image data;
- the correction coefficients being a fixed value when a signal level of the discrimination results is less than or equal to a prescribed value, and the correction coefficients being a value less than the fixed value when the signal level of the discrimination results is greater than the prescribed value.
Dependencies are inferred from the claim text.