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Old Dec 19, 2003, 5:43 AM   #1
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Default noise, noise reduction and jpg artifacts

I see a lot of newbies confused as to what these really mean, and/or look like. Here are a few samples to help define those terms. As follows, image of my sister's cat, Cayman, shot at different ISO's to show image noise (I will use the ISO 1600 to demonstrate the noise reduction and JPG artifacts):

The next sample is one where strong noise reduction was applied, similar to what some cameras will do to images:

And the next sample is what high compression looks like, in all of its JPG artifact glory:

On the sample where noise reduction was applied the image has a paited look at 100% and detail is lost in Cayman's fur. High JPG compression leaves a squarish pattern across areas of flat colors or a slight gradient of color, which is referred to as JPG artifacting. Some cameras may employ other methods of compression, but the end result is quite similar in apperance to my sample. You'd usually get this look when using the lowest quality setting in most cameras. Also, high compression will affect colors as well, in the way of less saturated colors that is. And lastly notice the "garbage pixels" that show up around the text. This happens around areas of really sharp contrast.

The following is what noise reduction and high compression together look like:

It's not a pretty sight ops: Hope this helps to sort things out so there's no more confusion
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