Oxygen From Hong Kong, joined Sep 1999, 675 posts, RR: 1 Posted (12 years 9 months 3 weeks 2 days 20 hours ago) and read 4299 times:
Hi, I was just reading through some instructions of a noise reduction program, and I came across a work 'luminance noise'. What does that mean? The passage also mentioned 'Cr and Cb ' channel. What does that stand for ?
Thanks very much !
Ckw From UK - England, joined Aug 2010, 813 posts, RR: 14
Reply 1, posted (12 years 9 months 3 weeks 2 days 17 hours ago) and read 4234 times:
Luminance noise is the term for one component of the noise generated by CCDs - this is the "grainy" look some images have. CCDs also generate chroma noise which produces red and blue specks.
Cr and Cb I think refers to a video technique of processing images (an alternative to RGB) in which colours are somehow derived by processing just the red and blue channels, plus a brightness channel - sort of like the LAB format available in Photoshop and other packages for processing photos.
Dripstick From Canada, joined Dec 2001, 2364 posts, RR: 19
Reply 2, posted (12 years 9 months 3 weeks 2 days 13 hours ago) and read 4177 times:
Luminance noise: luminance noise is an abrupt change in brightness between pixels. Sometimes called "high frequency pitting", this type of noise appears as grain or dots in the image.
Chrominance noise: Chrominance noise is an abrupt change in the color (hue) between pixels or adjacent sets of pixels. This noise appears as small color streaks or "veins" in what should be smooth, unchanging color.