Jpeg Compression - Nikon D300 User Manual

JPEG Compression

(User's Manual: D300S page 70; D300 page 58)
JPEG compression allows you to further fine-tune the level of
compression of your JPEG images. The JPEG format is
always a compressed format. The Image quality settings for
JPEG images include fine, normal, and basic. Each of these
settings provides a certain level of compression of the file
size.
As discussed previously, a JPEG fine file has a 1:4
compression ratio, while JPEG normal is 1:8, and JPEG basic
is 1:16. A JPEG file is smaller in size than a RAW file or
TIFF file—especially TIFF.
JPEG files will normally vary in size when the subject of one
image is more complex than that of another. For instance, if
you take a picture of a tree with lots of leaves and bark
against a bright blue sky, JPEG's compression formatting has
a lot more work to do than if you took a picture of a red
balloon on a plain white background. All those little details in
the picture of the tree cause lots of color contrast changes, so
the JPEG file size will naturally be bigger for the complex
image. In the balloon image, there is little detail in the balloon
or the background, so the JPEG file size will normally be
much smaller. The less detail in an image, the more efficient
JPEG compression is.
What if you want all of your JPEG images to be the same
approximate size? Or, what if file size doesn't matter to you,
and quality is much more important? That's what the JPEG
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