Photoshop for Photographers ©
Bob DiNatale
Scanning... Reading: Chapters 4 & 5 Studio Techniques by Ben Wilmore
  "The difference between failure and success is doing a thing
nearly right and doing it exactly right. - Edward C. Simmons 		 
Optimizing scans INPUT into a computer has everything to do with knowing the final OUTPUT!
File Resolution Chart for Output Media [For a test to optimize your own system, Click here]
Output Media: File Resolution: [DPI scan rate x scanned area x scaling]

Epson Photo Printer
Magazines and Brochures
Newspapers
35mm Slides
E-mail
Web Pages
PowerPoint Presentation

 150 pixels per inch
266 pixels per inch
85 pixels per inch
2400 pixels per inch
200 pixels [.JPG medium or low]
# of pixels dictated by page design [.JPG medium or low]
800 pixels [.JPG medium or high]
Scanning Software:
Although scanning software can be purchase separately it is always included with the scanner. This is as important as the scanner itself and should be a main consideration when purchasing a scanner.
A good scanning software should have the ability to:
1)
 enter Input values for width and height along with the ability to "lock" those values. This will maintain the aspect ratio [shape] of the selection bounding box
2)
 enter Output size in either inches or pixels
3)
 enter desired "DPI" value
  (the ability to enter a Scaling value is optional because it should adjust automatically as needed)
Note: when setting Output value in Pixels, entering a DPI value is not necessary.
Revision 3.1


Scanning Methods:
Methods 1 & 2 are not recommended but need to be mentioned. Methods 3 & 4 are the best and require a bit more understanding of output resolution requirements.
Method 1 ...getting the most your system can give!
1 - Set DPI at maximum scan rate
2 - Select desired area with "bounding box" and scan.
The run and gun approach... it's like using an 8x10 Deerdoff to shoot passport photo. You will create the biggest files which is necessary for the "best" and "largest" output you can achieve with your system. It will also tax your system for memory, storage space and processing time. The first step in Photoshop with a file produced in this manner is to "Resample Image" [bicubic] for the final output media then continue with your work.

Method 2 ...scanning software that has No scaling and No Output settings!
1 - Set DPI at desired scan rate (if available)
2 - Select desired area with "bounding box" and scan.
3 - Set "output" quality... Good luck!
Settings are something like "Good / Better / Best". This is to make it easy for beginners but the lack of controls soon leads to frustration ...try to find another software or mode setting.

Method 3 ...Scanning software with INPUT, OUTPUT and DPI settings.
Using this method will insure that when your scan is opened in a page layout software the dimensions will be proper.
1 - Set the DPI for desired Output resolution. (see File Resolution Chart above)
2 - Preview original sample and select the desired area with "bounding box" [input]
3 - Enter in final print size in inches [output] ...the software will calculate the scaling necessary.
4 - Scan
This will create a "file resolution" that when opened in Photoshop will produce an "Images Size" of the desired size and resolution. - See Power Tip below

Method 4 ...Scanning software with INPUT and OUTPUT settings.
Setting Output to pixels is usually done when scanning for web or multimedia presentations however it also can be used for outputting to print. To determine the amount of pixels needed for printing simply multiplying your final print size by the desired print resolution.
Before starting set your output units to "pixels"...
1 - Determine final pixels needed for output - (see File Resolution Chart above)
2 - Preview original and select the desired area with "bounding box"[input]
3 - Enter Pixels needed [output]... the software will calculate the scaling necessary.
4 - Scan
When viewing these scans in Photoshop under the "Images Size" menu, don't worry about the Print Size and Pixels/inch... when you set the "Print Size" (with "Resample Image" unchecked) the Pixels/inch will fall into place.
Revision 3.0

Power TIP! ...Setting aspect ratio of the final print during the scanning process!
Ever scan an area of a photo or slide and after "doing your Photoshop thing" you get ready to print the file only to find the shape to be different than the printing paper? You either have to crop the image or print with a wider border on one side... the proverbial round peg in a square whole... or the not so proverbial "one shaped rectangle into another shaped rectangle whole".

Well here's a solution... set the aspect ratio of the final print during the scanning process!
Most scanning software provide a way to "lock" the input setting for a fixed size... this is good - very good and necessary for this tip to work. Set the aspect ratio [width / height] of your final print size into the "input"of your scanning software. For an 8x10 print enter "4x5" or "1x1.25"into the input then "lock". When you drag the bounding box it will get larger or smaller while the aspect ratio ("the shape") of the box (and your final print) is maintained. When you have the desired composition, simply set the final print size and the output resolution desired [Method 3] or enter the pixels output needed [Method 4]. The scanning software will adjust the scaling. After scanning you will have a file with the proper resolution and shape of print!
Typical Scanning Request:
Your given a 4x6 inch print with the final output to be an 8 x 10 print from an Epson Photo printer.
The process:
  - Enter the desired DPI value = 150
- Enter an input value of Height = 1" and Width = 1.25" [an 8x10 aspect ratio]
- Lock the Input to maintain the aspect ratio
- With the bounding box, select a composition from the 4 x 6 inch print
- Enter an Output value of Height = 8"
Because the aspect ratio is locked:
  - the Output Width value will = 10" and the scaling factor will adjust as needed.