Please see your scanning software documenation
to learn how to adjust the following controls.
Scanned images, which are composed of pixels,
are represented as bits and bytes (a byte equals 8 bits.) In addition,
each pixel is represted by a bit-based number which is assigned
a value in a color table. The number of bits assigned to each
pixel is called color depth or bit depth.
When there is is only one bit of computer memory
assigned to each pixel, only two values may be represented, usually
black or white. When 8 bits are used to define each pixel, 256
color values are possible. When 24 bits are used for each pixel,
16.7 million colors are possible. We recommend you scan at 8-Bit
for black and white (to account for shades of grey,) and at 24-Bit
for full color.
The resolution of scanned images is described
in terms of DPI (dots per inch.) The scanning resolution should
be high enough for the use of the image, but not so high as to
waste storage space. Most print work requires images at 300 to
Do not scan at a higher resolution than the native
resolution of the scanner (eg. Epson 2400 Photo's native resolution
is right there in the name - 2400 dpi.) Scanning at a higher resolution
can cause blurriness.
Adjust your scanning resolution if you want to
enlarge or reduce that image size. For example, if you want an
image at 300 dpi and at twice the original size, scan at 600 dpi.
TONAL RANGE FOR PRINT
A scanned image, when optimized for a computer
monitor, may have a tonal range of 0% (pure white) to 100% (pure
black.) When scanning for print, the tonal range must be adjusted
for press conditions.
Dot gain (the phenomenon of halftone dots printing
larger on paper than they are on films or plates, reducing detail
and lowering contrast) will dictate a maximum value of about 85-92%,
depending on the press conditions and paper stock. The tolerance
of the platemaking process will dictate a minimum value of 3-5%.
For a photo with full tonal range, you need to decrease the contrast
in your scanning histogram.
MORE ABOUT COLOR IMAGES
Scanners and computer monitors use a color space
called RGB (red-green-blue.) RGB is a system which combines red,
green and blue light to make all colors. However, a printing press
uses a different color system, called CMYK (cyan-magenta-yellow-black.)
CMYK combines translucent inks on paper to make all the various
colors. After you scan your color image into your imaging software
(such as Photoshop,) you will need to convert the file from RGB
to CMYK. See your imaging software documentation about the various
options available to you. Different methods (for example, Undercolor
Removal versus Gray Component Replacement) can have different