Graphics Programs Reference
In-Depth Information
Although JPEG is a good format for distributing images (due to
their compatibility and small file size), it is not great for image
acquisition or production. A JPEG file is lossy, meaning that every
time you modify it in Photoshop and resave as a JPEG, additional
compression is applied to the image. Over subsequent compres-
sions, the image quality can noticeably deteriorate. This is similar
to the act of making a photocopy of another photocopy: Addi-
tional image deterioration occurs with each processing step. The
visible loss in image detail or accuracy is referred to as
compression
artifacts
.
The JPEG Options dialog box is avail-
able when you modify or first save a
JPEG file with Photoshop. When sav-
ing, you can adjust the Quality slider
to reduce file size. It is best to leave
Quality set to maximum if you will
be making future edits to the image:
This applies the least compression that
could damage the image's appearance.
So, if JPEG is inferior, why do so many people use it? Money and
resistance to change are the simple answers. It's cheaper to shoot
JPEG images because you don't need to buy as many memory
cards (however, the price of memory cards nowadays is so low that
this is almost a moot argument). Certain scenarios like sports and
photojournalism often rely on the speed associated with smaller
files as well (but camera manufacturers are adding larger buffers
This image was captured as both a raw and a JPEG file when it was shot. The picture was taken with a Nikon D800, which
can simultaneously write both files to the memory card when shooting. The raw file offers significantly greater latitude for
post-processing and can recover more detail than the JPEG version.
