What does the following option mean when saving an image Paint Shop Pro 8?

Question

Chroma subsampling

Answer 1

Simple :

This feature relates to jpg format.

without chroma subsampling jpg compress each color channel individually.

this is particularly interesting when you whish to print in high quality or when you have some particular application like anaglyphs (stereo pictures with red/blue glasses)

compression is made only with comparizon the the neighborough pixel on the same channel.


with chroma subsampling , jpg will put a maximum of information as level of grey (conducing to have the same value in the three chanels r,g,b)
this reduce the size of the file, but destroy a little more the information contained in the original.

example : a block coded (r=123,g=122,b=124) will come back basically (r=123,g=123,b=123)


Due to the fact that computers are quicker and HDD wider than before, my personal advice is to save WITHOUT chroma subsampling and with the beter quality possible. a few hundreds of Kb will never kill you.

Answer 2

I have a couple of links to add to those Ipshwitz posted. One is from a blog that talks about chroma subsampling in PSP 8 in particular. The second, which I found on the blog, is a more in-depth article on the subject.

JMB

Answer 3

I don't know if this helps, but i found the following links:

http://en.wikipedia.org/wiki/Chroma_subsampling
http://www.answers.com/topic/ycbcr-sampling