Light Intensity Software

Don't have a clue. The free software Picasa has a feature that does an analysis of the photo and presents a graph of the picture's colors. I never use it so I don't know if it might help you, or not.

If you download this software, it will insist that you let it copy all your pictures into it, but you can always delete it.

I think what you're looking for is a program with a histogram. I believe this has what you want, but it's not free, http://www.corel.com/servlet/Satellite/us/en/Product/1184951547051#versionTabview=tab1&tabview=tab0

This site may yield something that won't cost you.

http://download.cnet.com/windows/

It sounds like you might be able to use the software that astronomers use for image processing (one example linked below). I haven't used this, but I've heard of many astronomers (amateur and pro) who use it. If this doesn't quite fit your needs, you could try a search on 'scientific image processing software'. The software that Meade (a telescope company) supplies for its astronomical cameras (AutoStar) can provide intensity readings on the digital images it takes; it might might work for any digital image.

http://www.willbell.com/aip/index.htm

I don't know exactly what you want to do and I don't know if you are willing to do any programming if you don't find a pre-made package. If you end up doing it yourself you can use Perl and PerlMagick (a branch of ImageMagick) and perl under Linux to get the color values of each pixel in the image. You can then process them in any way you want.

If you don't know Perl it is pretty easy to get started with. It is a very powerful language but you can do a lot with just a little bit of knowledge.

There are some advanced capabilities under Gimp (GNU Image Manipulation Program). They have "script fu" and other macro and program interface type features. I don't recall anything like you are asking for, but I never looked. You might add "gimp", "imagemagick", "perlmagick" (yes, that is how they are spelled), script fu, histogram, LInux and image processing to your collection of Google searches. It is amazing what is out there in the Linux community and almost everything is 100% free. There may be something available (legally for free) that can be added to Gimp to do what you want.

If you are stuck in the M$ world then active state perl and perlmagick can be installed on M$. I don't recall for sure, but I think I used to install Gimp on Windows also.

Bruce

Yepper, Gimp is still available for Windows. I run it on my Win7 system. And it's still the best (free) imaging processing system around, IMO.

Hooker

You mention nothing of the image format you want to analyze, which could have a significant impact on what your software choices might be. I am going to go out on a limb here, though, and infer from your brief description that you may be looking to extract astronomical data- in which case you may find what you are looking for at http://www.astromatic.net/.

ImageMagick may also have some tools you might find useful...