TH31020A - Quality correction circuit for video signals - Google Patents

Abstract

DC60 (01/06/41) The image signal level is corrected without degradation of background image patterns such as skin tones or portraits. The gain controller operates and outputs an adjusted value using the histogram generated by the histogram generator. The average of the image level on the monitor is detected by the average image level detector. The histogram correction circuit calculates the find table, and the image signal correction circuit corrects the image signal. The image signal level is corrected without degradation of background image patterns such as skin tones or portraits. The gain controller operates and outputs an adjusted value using the histogram generated by the histogram generator. The average of the image level on the monitor is detected by the average image level detector. The histogram correction circuit calculates the find table, and the image signal correction circuit corrects the image signal. The image signal level is corrected using the find table.

Claims (6)

1. The correction circuit consists of: a histogram generation section for generating the first histogram from the input video signal; a gain control section for outputting the first adjustment value to correct the first histogram; a histogram correction section for generating the second histogram, which is corrected by switching the first histogram according to the first adjustment value; and a video signal correction section for correcting the input video signal according to the corrected second histogram. 2. The level correction circuit as defined in claim 1 shall subsequently consist of an average image level detection section for detecting the average image level of the input image signal and outputting the average image level to the gain control section; and where the gain control section shall switch the first adjustment value according to the average image level. 3. The level correction circuit as defined in Claim 1 is such that the video signal correction section generates cumulative and normal operations based on the second histogram corrected by the histogram correction section and switches the video signal input according to the cumulative and normal operations. 4. The level correction circuit as defined in Claim 1, is subsequently comprised of an average image level detection section for detecting the average image level of the input image signal; where the average image level detection section outputs a second adjustment value if the average image level is greater than the initial correction level, and a third adjustment value if the average image level is less than the initial correction level, and the gain control section switches the first adjustment value according to the output of the average image level detection section. 5. The adjustment cycle as defined in Claim 4 is such that the first adjustment value is limited by a limiting level. 6. The adjustment cycle as defined in Claim 1 is of the type where the first adjustment value is constant (Claim 6, page 1, figure 8).