(Dos & Don'ts)
Paper used in the printing process acts like a blotter to the ink.
Consequently, any photo or "screened" area will look darker
on the printed sheet than what you probably saw on your monitor. This
is called "Press Gain". The amount of gain depends on how
porous the paper is that is being used. Check with your printer beforehand
for advice on how you should scan your photos.
Got a color photo of people that looks real dark in the faces when
scanned as black and white? What's happening is that your scanner
is seeing the combination of colors in the faces as a dark tone
when scanned as black and white. If you have a photo manipulation
program like PhotoShop, scan the photo in color and convert to cmyk.
Check each individual color channel and you'll most likely find
that the Cyan channel has the most detail in people's faces. Delete
all the channels except for the Cyan and use that for your black.
Scanning from a printed page? Chances are you are picking up a
pattern when you print the scan. This pattern is called "moire"
What's happening is that the halftone pattern that your computer
creates is conflicting with the halftone pattern that already exists
on the printed original. Some scanners come equipped with settings
to reduce moire, if yours does check your manual on how to change
settings. Sometimes rotating the image on the scanner can decrease
the moire. There are also methods of reducing the moire using Photoshop.
1) Despeckle: Go to Filter, Noise, Despeckle
2) Gaussian Blur: Go to Filter, Blur, Gaussian Blur. Use 1 pixel
3) Median: Go to Filter, Noise, Median using 1 pixel
Sometimes when scanning a printed piece, you may see the image
on the other page bleeding through. Putting a piece of black paper
behind your original can minimize this problem.
Okay, so now you know that you should scan your photos at no more
than 300 dpi now here's some more helpful information to make your
files more manageable. If at all possible, you should scan your
images to the size that they will be in your final printed piece
or at least somewhat close to the size and here's the reason why.
If you reduce an image in your page layout program, you still retain
all the information of the original image. If, for example, you
have a 50 megabyte scan and reduce it in your page layout program
to ten percent of its original size, the resulting file will be
50 megabytes. If, however, you open the image in Photoshop and reduce
it to ten percent its original size (make sure Photoshop is set
to resample) then the resulting file is only around 500 K. As you
can see, the image will be much smaller and more manageable.