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Lots of ways, depending on what you mean.

Maybe you should start with learning about "homomorphic filtering."

http://www.yqcomputer.com/

http://www.yqcomputer.com/

http://www.yqcomputer.com/ ~stella/papers/blairthesis/main/node33.html

http://www.yqcomputer.com/

You could lowpass filter the log(intensity) of your image (you need to avoid the log(0) problem on black pixels - add 1 to black pixels (Uint8 format) perhaps).

An image consists of the reflection matrix of your subject (Rm) multiplied by the illumination (I). Thus

Image = Rm*I;

Finding the log gives you

log(Image) = log(Rm) + log(I);

Which is now ameanable to DSP filtering.

In general the spatial frequency matrix of the reflection matrix contains higher frequency components than the illumination matrix, (which for an ideally set out picture would be simply a uniform field). Thus low pass filtering will severely attenuate the reflection matrix contribution, and provides you with an approximation to your illumination field. Simply antilog the result and you may be home and dry.

This process is known as Homomorphic filtering, and sometimes works well.

You can of course imagine an image for which the assumptions on which this technique is based are not valid, and in which case the process wont work.

Regards

Dave Robinson

2. Global Illumination and Solid Angle

3. definition of global illumination

4. How to Vary Color Temperature of Image Illumination

5. phong illumination model in ray tracing context

6. OO programming - illumination?

7. OO programming - illumination? - whoopsie

8. fixe pipeline illumination probleme

9. reflections, shadows and indirect illumination

10. Computing direct illumination from a non-uniformly scaled area light source

12. OO programming - illumination? - whoopsie

13. correcting background non_uniform illumination

14. Indirect Illumination Observation and Tip

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