Chroma Subsampling - DPChallenge Forums

03/15/2005 10:10:05 PM · #1

Anyone familiar with Chroma Subsampling? I'm using Paint Shop Pro 9 and have an image that I've saved using this option and the image looks great when I view it in Paint Shop Pro. Tried to upload this image for my challenge entry - errors out (file corrupted). Won't open in Internet Explorer either...

This kinda bites because the image looks great using this option. Guess if I'm going to print it directly from PSP it's ok. Bummer - I was so excited!

Tamron SP AF 28-75mm f/2.8 XR Di for Nikon

03/16/2005 06:56:13 AM · #2

Nothing from the evening people - any daytimers have any info on this? Thanks.

blemt

Nikon D70

03/16/2005 07:01:16 AM · #3

Check how you saved the file. Make sure it's a jpeg. Lot of times these programs will save to a proprietary format. Just go to the Save As menu and select .jpeg from File Type.

Only thing I can think of.

Clara

Canon RF 24-70mm f/2.8 L IS

03/16/2005 07:28:49 AM · #4

Thanks Clara. It worked! And I'm supposed to be a computer guy - sheesh. The file that was corrupt, when saved as (without the Chroma), opens and looks just great.

I try to limit the number of times that a file is resaved as a jpg to limit data loss and assumed if I did a save as on this file I would lose the result the Chroma Subsampling gave me.

For anyone curious - here is a help description of what Chroma Subsampling does. There are various levels that you can apply.

With chroma subsampling the file size of the JPEG is reduced by averaging the color information for every 2 x 2 square of pixels. You can change this setting to have a larger area of color information averaged.

kirbic

Canon EOS R5

03/16/2005 09:25:35 AM · #5

Originally posted by glad2badad:

I've never heard anyone report that the results of chroma subsampling were desirable before... normally the only reason this is done is file size ruduction. The color averaging over the 2x2 px area (or larger if selected) is the reason that JPEGs often look "blocky" as opposed to smooth. Thus, subsampling is normally on the list of "things to be avoided."

e301

03/16/2005 10:40:03 AM · #6

I do a small amount on almost all of my dpc entries, and have never had an adverse comment reflecting it. It's a trade off, of course, between definition and colour, and of course the fact that very few of my shots have great big areas of the same colour in them.

e