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Old August 18th 07, 08:38 PM posted to rec.photo.digital,uk.rec.photo.misc
A.Lee
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Posts: 6
Default Compression in JPEG files in digital cameras

wrote:

I need some help in explaining the JPEG compression feature in digital
cameras. My camera (which likely is similar to most others) has the
feature to compress the photo JPEG files in the storage card.
It also has the choice to have different pixel sizes (example:
3000x2250, 2000x1500, 1024x768, etc). What is the difference of the
above two features?


Smaller files size/pixel size equals poorer quality.On the other hand,
it means more pics on the card. With the cost of memory so low now, it
isnt really much of a feature now, as there is no point in saving in
smaller formats.

If you store a 3000x2250 pixel data in compressed mode,
does it lose its quality?


Yes. Any system that saves as jpeg will be a compromise between file
size and quality.

Can it be re-instated to full uncompressed size without loosing photo
quality?.


No.

When I compressed the data, it will fit more pictures in a single
storage card. But, is it the same if I choose 2000x1500 pixel and no
compression instead?


No. As above, if you save as a jpeg, you will lose quality. For the best
quality, pics should be saved in RAW format, or any of the other
proprietary no-loss formats that camera makers use.
Alan.

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