Masked stretch to protect the background.

[Graham]

Howdy!

Is there a way to perform a stretch on an image with a mask to protect the background if the camera is a bit noisy? I tried a luminance mask on an unstretched RGB image straight form channel combination and only seemed to be stretching the mask.

Thanks,

Graham.

[Carlos Milovic]

Yes, this is one way.
Another is to use the ExponentialTransforms process, wich includes a mask protection of the background. Anyway, it was intended for non-linear images, so you may try first to stretch the image with the histogram transformation, or autohistogram (in the later, you may select other stretching functions, like the gamma and logarithmic functions, which will yield a less contrasted image). I would do that, and then play with exponential transforms.