22. March 2002
CCD scanner internals

Should I use the image manipulation software that comes with my scanner or should I make "raw" scans and then manipulate them in Photoshop? What is best?
This question is often asked and debated because it does not have a simple answer.
However, a related question can be answered it seems.
This question is:
Will my altering of levels, unsharp masking etc. have any impact on the way my scanner is outputting or is it "only" or "just" post scan corrections?

I'm no scanner expert myself, so I have asked a number of people to help me out on this question.


The question
A scanner is always bundled with some software that will help your computer to communicate with the scanner. Often this software offers different kind of image manipulation utilities, like levels adjustment, unsharp masking, brightness, contrast and a lot of other things dealing with color balance etc.
So, the main question here is: "Does altering any of these parameters change the output from the scanner itself?". Or in other words: "Will the image manipulation software that is bundled with the scanner be able to change the "raw" output of the scanner hardware?".

The answer
The simple answer is: No.
The raw output from the scanner remains the same, no matter what changes you make using the scanner software.
However, some scanners DO offer a way for changing the analog gain from the CCD and this will actually change the output from the scanner itself, but making changes to levels, brightness and contrast or whatever will NOT change the actual output from the scanner.




Disclaimer
I need to say, that I can not be 100% sure that this will cover how ALL CCD scanners work, but it's my impression that this is how MOST work.
But maybe this can help YOU decide how YOU will work with YOUR scanner.

What else
Please remember that this does NOT answer the question wether or not to use the image manipulation software that is bundled with the scanner. There are many pro's and con's on that question.
On some scanners you can save your settings and always use them when you scan, which can speed up your work.
Scanner software offers an easy way of dealing with the 16 bit raw data "while you scan".
On the other hand, some people won't have their files "tainted" with whatever the scanner software does to the images - they'd rather scan as a "raw" file and then use ICC profiles to convert to other color spaces.

Thanks to...
IMACON, Denmark
DFA (Nikon), Denmark

...for kindly answering my questions.

[Update 14.06.2002]
Here's a graphic illustrating the scanning process of a Nikon LS-2000 scanner.