Quote:
Originally Posted by banjobama
I also saw it mentioned in a different thread that PNG or GIF format is better for the pictures that JPEG, is that true?
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It depends on the picture, and it depends on what is meant with "better".
JPEG is a "lossy" format. The resulting image after it is saved is not the same as the original image, it has been modified to make it easier to compress. This works fine for real pictures, because the modifications are often unnoticeable (unless the compression is very drastic), but for "clean" drawings with lots of flat colour areas, it's easy to get visible artifacts. Note that everytime you save the image, you lose some quality, so it's better to use it only in the final save, and use another format for the intermediate steps.
PNG is a "lossless" format. The saved image is exactly what was there before, so you lose nothing by saving again and again. The drawback is that it often generates (often) larger files for pictures than JPEG (because it saves all the details that won't be noticeable anyway). But it works very well for plain line drawings, computer screenshots, etc., for which it generates smaller files than JPEG and without the artifacts.
GIF... don't use it, it's like PNG but limited to 256 colours and worse.
For scanned images, I'd only use PNG if you manage to get a very clean image, very "black and white". But anyway, try both, JPEG (with ~85% quality, at least) and PNG, and decide according to the quality on screen (zoom in to see the details, and increase the brightness) and filesize. If PNG is smaller or similar in size, take it with eyes closed; if not, take JPEG only if the artifacts are not severe.