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Colour Difference Between 500px & 1000px image

hobbs Plus
16 1.3k Japan
14 Nov 2006 12:28PM
Has anyone else noticed that when you load a 1000px image that the 500px version that the site produces is quite often slightly different colour wise. I did a test the other night using the colour meter that you get with Macs and there is a difference in the RGB percentages.

Out off interest does anyone know why?
peter shilton 16 1.1k England
14 Nov 2006 1:05PM

Are both background colours the same?
14 Nov 2006 1:28PM
not too sure about the color, but always have the impression that the overall quality of the 500 pixel image is worse, as if compressed. Sometimes it really lacks sharpness vs the larger version.
hobbs Plus
16 1.3k Japan
14 Nov 2006 2:34PM

Quote:Are both background colours the same?

Its the overall image, the colour varies by a couple of percent, I only realised on a recent image I put up of a cheetah. Basically the 500px image looks flatter.
AnthonyM 15 428 2 United States
14 Nov 2006 3:23PM
Are you talking about "The Watcher"? I only notice a slight difference where there is some higher contrast in small areas, such as in the green on the trees. These small areas are going to be compressed and averaged to some extent in the smaller images and you will likely lose the nice sharp color of the larger image can provide.

Then again, my eyes are not well trained at this stuff (and probably not capable to begin with Smile ), so maybe you are seeing more of a difference than I can. But I think this is to be expected.

Just another benefit of being a member and being able to upload those larger images.
hobbs Plus
16 1.3k Japan
14 Nov 2006 4:01PM
Yep, I think it's down to the compression.
KatieR 16 6.2k 6
14 Nov 2006 4:05PM
You know what the answer is, Nick ...

black and white :o)
hobbs Plus
16 1.3k Japan
14 Nov 2006 9:22PM
Would that be film as well? ;o)
hobbs Plus
16 1.3k Japan
15 Nov 2006 10:42PM
Ok after doing a test I think I have an idea of whats happening, I uploaded a picture of 3 rectangles coloured in. One in red, one in green and one in blue at 1000px. I then tested the coulours using a colourmeter the red and the blue measured the same in both images 99.6% of the corosponding channel. But the green measured 100% green in the large version, in the small version the green measured 100% green and 0.4% blue. So the compression slightly altered the green, I think this could potentially have a bigger effect on certain colours that need the blue and green channel mixing to make them. Hence why pictures that are uploaded at 1000px that have a strong use of the blue and red channel look flatter in the 500px version.

Right I'll get me coat!!!!
IanA 16 3.0k 12 England
15 Nov 2006 11:27PM
Yes, you do need to get out more!! Wink)


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