If you choose Image ->Adjustments->Hue/Saturation from the menu bar, you will see the following dialog box.

 

 

In the box, you will see slider switches labelled Hue, Saturation, and Lightness. (You can enter values directly in the fields provided if you wish.) You will also see two colour spectrum bands running along the bottom of the box. Near the top you will see a drop list labelled Edit. You can expose the options in the list by clicking the down pointing arrow.

 

 

From the Edit drop list, you can choose from reds, yellows, greens, blues, cyans, or magentas. Basically, the effects of moving the slider switches will be applied to the colour tones selected from the Edit drop list. If Master is selected, the sliders will affect all of the colour tones globally.

 

If you move the hue slider, you will see the hues (shades of colour) in the active image change. (Notice that by default, the sliders are at a level of zero for the original image conditions).

 

 

Here you can see that Master is selected in the edit drop list, and that all sliders are at zero. This is the image in its original state.

 

 

Here is the image with the Hue slider set at -70. Notice how shades of colour have changed compared to the original.

 

 

Here is the image with the Saturation set at +70. Notice the intensity of the colour.

 

Here is the image with the lightness set to -50. The shades of colour and the vividness of the colour are pretty much the same as the original. However, the image is noticeably darker.

 

(Pressing the Alt key toggles the cancel button between Cancel and Reset. If you click the button when it is labelled Reset, the values of the sliders will return to zero.)

 

If you choose a colour from the Edit drop list, you will see graphical indicators added between the two colour bands at the bottom of the dialog box.

 

 

These indicators point out the chosen colour group in the top colour bar (in this case, yellows) and indicate the effects on these colours in the lower colour bar. The selected colour group is shorn by the center indicators (bounding a grey area). The indicators on either side of this area show neighbouring shades that will be affected to feather or blend the changes.

 

 

Here the hue has been adjusted to -42. Notice how the Yellows have changed in the lower colour bar as compared to the top colour bar.

 

If you want to be more specific in selecting the colours to modify, you can use the eyedropper tool at the bottom just above the colour bars. If you click the leftmost eyedropper tool, you will be able to click anywhere in your image and the colours of the spot you click on will be chosen for adjustment. If this is a colour group that in not in the Edit drop list, it will be given a name and added to the list (such as Blues2). You can use the eyedropper with a (+) next to it to add colour to your working range, and you can use the third eyedropper with a (–) next to it to subtract colour from the range. Once you select one of these tools, just click an area on the image to add or remove the sampled colours from the working range.

 

If the checkbox labelled Preview is cleared, you will not see the adjustments you make reflected on the image. If you put a check in the colourize checkbox, you can create a colourized version of the image similar to greyscale (like sepia tone).

 

When you have finished adjusting the hue, saturation, and brightness levels, click OK to implement the changes.

 

If you would like to keep a given set of adjustments, you can save the configuration by clicking the Save button in the dialog box. If you would like to load a saved configuration, click the Load button.