Contrast zoom of image signals and overflow bit compensation system and method

Abstract

The invention is used for avoiding the appearing of large highlight area in image when the signals are overflowed, and restoring the bright and dark levels of original image. The system comprises: at least one memory and at least one image processor. A contrast scaling check list and a overflow compensating check list are pre-saved in the memory; the image processor comprises a grey scale estimating unit, a contrast scaling unit, a overflow estimating unit and a overflow compensating unit. When the overflow estimating unit decides a certain pixel is overflowed, the overflow compensating unit will selects a overflow compensating parameter from the overflow compensating check list to reduce the grey scale value of said pixel in order to overcome the overflow.

Description

technical field [0001] The present invention relates to an image signal processing system and method, in particular to a system and method for image signal contrast stretching and overflow compensation. Background technique [0002] It is known that in video image products or components, there is often a need to use image processing to adjust image quality. For example, the TV is designed with functions such as brightness (Brightness), contrast (Contrast), hue (Hue), color saturation (Saturation) and other adjustment functions for consumers to adjust to their preferred picture quality. However, the problem that consumers often encounter is that after using these options to adjust the image screen, it causes a large area of ​​saturation and translucency after adjustment, that is, the image or color that can distinguish between bright and dark levels is completely brightened after adjustment. , but the original level and color deviation cannot be distinguished, which is the p...

AI Technical Summary

Problems solved by technology

However, the problem that consumers often encounter is that after using these options to adjust the image screen, it causes a large area of ​​saturation and translucency after adjustment, that is, the image or color that can distinguish between bright and dark levels is completely brightened after adjustment. , but the original level and color deviation cannot be distinguished, which is the phenomenon of oversaturated gray scale overflow (Overflow), that is, the gray scale has reached the maximum value and the original level cannot be distinguished

[0003] As another example, most video processing ICs provide a variety of image adjustment and enhancement functions for the designer to match the best adjustment settings. However, after the image is processed in multiple stages, it often causes saturation and overflow. Phenomenon, the picture that finally appears on the display will show a large area of ​​translucent phenomenon, which will affect the quality of viewing

[0004] Most of the current solutions are aimed at image overflow. The simplest countermeasure is to limit the size of the image gain in image processing and minimize the possibility of image saturation.

However, the image signal often undergoes more than one level of image processing. If the image signal undergoes multi-level adjustment and enhancement processing, the number of gray scales in the image will become less and less, resulting in the problem of insufficient image continuity. Overall brightness is also reduced, resulting in poor contrast

[0005] In addition, in order to avoid the occurrence of overflow, when processing image signals, the gain value (Gain) is usually less than 1.0, so that after multi-level image processing, the gray scale value of the image will become smaller and smaller , the contrast is getting worse and worse

For example, an 8-bit 256-grayscale image has a maximum grayscale range of 0 to 255, but in the actual application of a video system, due to the characteristics of the components used, parameter value settings, signal transmission attenuation, and distribution attenuation , noise suppression and image signal processing, etc., will affect the range of image grayscale, so that the grayscale of the image cannot be fully utilized to 256 grayscale, which will cause the dynamic range of the image signal to shrink, the brightness and color levels to decrease, and the contrast to deteriorate, etc., affecting Picture viewing quality

Images