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Can Colorwasher be used to normalize several photos that may be slightly different in white balance and brightness to facilitate joining these photos together in a single picture?

ColorWasher wasn't designed for the task of adapting several photos to each other. It was created to make individual photos look their best.

There is a free plugin called Metrix who does that. It is available at http://www.panix.com/~jnr/. Someone I know tested it. He wasn't too enthusiastic about it, but it seems to do the job for photos that aren't too difficult to adapt to each other.

would this be more suited to the task:

http://www.colorgrinder.com/Products/products.html
http://www.colorgrinder.com/Support/support.html

We were not talking about color profiles. Color profiles are used to keep images as they are when they are displayed or printed on different devices.

We were talking about adapting the color, contrast and brightness of two quite different photos to each other.