Jon Bagge is correct, it’s an operation ordering issue.
The HSL controls (which is where the saturation control is) is processed prior to the RGB controls. So you end up colorizing your desaturated image.
But there is a useful workaround for this situation using the Secondary color corrector to perform the desaturation:
Adjust your RGB controls as you like, and when you want to desaturate the image, select one of the Secondary color correction tabs. By default, nothing is selected. Check the “Invert Selection” which will cause everything to be selected. Now use the Saturation control in the Secondary tab to do your desaturation and I think you’ll get the results you’re expecting. Since there are six Secondary color correction tabs, you can use this workaround even when using (up to 5) secondaries; just use the last one for desaturation.
The order of processing operations is covered at the end of Chapter 3 in the Color Finesse Users Guide.
For Color Finesse specific issues you’ll probably get a quicker response over in the Synthetic Aperture forum. I caught this question by chance because Google Alerts happened to flag it.
Bob Currier
Synthetic Aperture