Principles
There are many brands of scanners available today. They do a nice job of
digitizing images. Using them is a bit like using a copier. You must make settings,
though, that will determine the resolution, file size, and screen size of you
image.
Each scanner comes with software to control the scanning process. There are many control programs. Most of these programs are activated as Photoshop plug-ins. To run these pull down under File in Photoshop to Import. This will activate the scanning software. The final scanned image will be dumped into Photoshop.
Whatever scanning program you use, save your original in an uncompressed format
to avoid loosing detail. Load the original into Photoshop and adjust or compress
into JPEG or GIF as needed after doing normal Photoshop image editing. (In almost all cases, use JPEG. This format is more suitable for continuous tone images. The only exeptions would be for animated GIFs or for images with transparant backgrounds. )
Scanning using a Photoshop Plug-in (SilverFast SE for example)
From inside Photoshop, pull down under File to Import and select the type of scanner you are connected to. (We use a SilverFast SE in our example). You'll see a new program load with its own windows. The folowing shows the windows after you've put a document in the bed of the scanner and hit the Preview button. This scans everything in the bed. Drag a box with the rectangle selection tool.
Before scanning make sure you set the resolution and other settings as shown in the example.
Hit Preview and wait while a preview scan is done.
Settings
The following settings are critical covering the circled items from top to bottom:
Scan Type : Normally the scanner scans at 42 bits/pixel. It uses 14 bits for red, 14 for green and 14 for blue. You will usually want to reduce this to normal 24 bit coding for Photoshop (since Photoshop does not support 42 bit -- it can do 48, but that is seldom better.)
Filter: Do not turn on an Unsharp Mask here. Do sharpening and other filters in Photoshop after the scan.
Image Type: Standard -- this reduceces color change effects. You should do these in Photoshop.
Scale: Make sure they are on 100 and the units are percent.
Resolution: Normally use 75 dpi for web work. If you want to enlarge the image, scan at a higher dpi. For printing, normally use 300 dpi. If you wish to print and to double the final size, use 600 dpi, etc.
This program automatically does some level adjustment on any settings set. If you click on the third icon along the top right row (the one that looks like a histogram), you'll get (for this image) something like that shown below. We've circled the black point and white point. The sscanning program has already set these. You can then adjsut them. When done, hit OK.
Doing the scanning
Finally, hit Scan. Wait. This takes a while. The scanned image will be loaded into Photoshop. Continue there.
Page maintained by Dr. Robert Fry. Last updated 27 March 2004.