Histogram equalization is good enough actually, but it is not parametric as i remember.

Can you explain a little bit more about "resolution"?

Do you mean normalizing image pixel values to a specific interval like 0-1?

Or do you mean image scaling?

@Omer Karaaslan: normalization in the sense of image scaling to some specific width and length, like rescale a character to 20x50 keeping the aspect ratio same.

Resample to the resolution you want, using a good interpolator.

If the original and the target resolutions have a different aspect ratio, you may need to add e.g. black bands to indicate regions where no information is available.

Maybe you can use ImageJ for rescale images using interpolation methods.

Hi Javed,

Two ways of resizing (keeping aspect-ratio) could be:

Matlab:

http://www.mathworks.es/es/help/images/ref/imresize.html

ENVI:

Basic Tools--->Resize data

you can use an ImageMagick to resize the image. Here is the example of the script

http://www.fmwconcepts.com/imagemagick/aspect/index.php

Matlab code: http://stackoverflow.com/questions/2605202/how-do-i-automate-the-padding-for-arbitary-images-using-matlab