Adjust H/S/L Dialog Box

This dialog box is used to adjust the hue, saturation and/or luminosity of an image or selected image data.

Check "auto apply" to apply the change as soon as it's made.

All of the graphics parameters have a user interface: just try it. Click the mouse down on one of the graphs and you'll find you can change its curve. So far I haven't found a really good use for this feature, but I'm sure there must be some out there.

Click the "Normal" button on each of the graphs to return it to normal (a straight line that means no change to the parameter.)

The luminosity section has an "Optimal" button. This command searches through the image to find the brightest and darkest color, then maps it to white and black, respectively. So if your image appears low-contrast or washed-out, this button is the best way to increase contrast. Of course, if your image contains white and black pixels already, this button will have the same effect as clicking "Normal".