12/13/2003
7:31:59 PM | Color depth is a bit confusing because it doesn't really
exist outside of the digital world. Basically it refers
to how many numbers are used to store each pixel's color
information. RGB uses three numbers one for Red, Green,
and Blue. It yeilds about 6.7 million possible colors.
Indexted color is similar though there only 256 possible
colors available. (though the palette of 256 colors
may vary from image to image)
In Photoshop you will probably scan your images in as 256
colors, and do all of your processing here. As a last
step in some cases you MAY want to save them as an indexed
color image. Note that I personally don't have a single
indexed color image on the site...(I am mainly pointing
out this feature because it is an important aspect of
digital image editting - though not as critical in
photography work) If you want to save your images as
GIF's you will need to reduce them to indexed color. If
you want to save them as JPG's you want to save them as
RGB images.
Notice that this image is RGB mode.
If you choose to change it to Indexed Color it may ask you
to flatten the layers. An RGB image can be built from
many different images stacked on top of each other...once
you save it as a JPG or GIF you will need to flatten the
image. (note that you can also flatten an image from the
Layer menu)
At the last step you need to choose the palette for the
newly created Indexed Color image. For the internet it is
a good idea to choose the web palette, or adaptive.
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