Patent ID: 7215366
Filing Date: 2007-05-08
Classification: H04N

Abstract:
1. A tone correcting circuit comprising: hue detecting means for detecting a hue component for each pixel from a first color difference signal R−Y and a second color difference signal B−Y; and gain controlling means for controlling for each pixel a gain for arbitrarily selected one of or an arbitrary combination of a luminance signal, a first color difference signal R−Y, and a second color difference signal B−Y depending on the detected hue component for each pixel, thereby correcting a tone only for an arbitrary hue, wherein the hue detecting means comprises a first bit shift circuit to which the first color difference signal (R−Y) is inputted, a second bit shift circuit to which a second color difference signal (B−Y) is inputted, and means for outputting for each pixel hue values corresponding to output values of both the bit shift circuits as hue components on the basis of a look-up table, and each of the bit shift circuits cutting the number of bits composing an n-bit input signal to m which is smaller than n, cutting, when at least the respective uppermost bits in the color difference signals are both zero, the upper x bits in each of the color difference signals, letting x be the smaller one of the number of bits, out of the bits from the uppermost bit to the (m+1)-th bit in one of the color difference signals, which are continuously zero from the uppermost bit and the number of bits, out of the bits from the uppermost bit to the (m+1)-th bit in the other color difference signal, which are continuously zero from the uppermost bit, and further cutting the lower (n−m−x) bits in each of the color difference signals when x is smaller than (n−m).