The conditional hue adjustment feature of EIE allows you to modify the hue of certain parts of an image, based on their existing hue values. If you are not familiar with exactly what hue is, think of it as the defining color of an object. If you look at a car and say "that car is red", then most likely the car is red in hue. The "intensity" of the color is another aspect, and this is known as the saturation. Also, there is a brightness component to a color which is refered to as "value" in the hue/saturation/value color model.

Hue is often the most interesting aspect of a color and the conditional hue adjustment can allow for useful changes in images with high hue contrast. For this tutorial we will demostrate with an image of a toucan. Start by opening whatever image you wish to work with in EIE by clicking the "File" menu, then "Open image into existing document...".

Unmodified version of the toucan image loaded in EIE

Next bring up the conditional hue adjustment modifier by clicking the "Modifiers" menu, then "Conditional hue adjustment...". The conditional hue adjusment window will appear. In this window you have the color wheel, which is where you define your adjustment range and the slider which alters the adjustment amount for pixels that fall within that range. For example, let's say you want to take the parts of the image that are green in hue, which in this case this is mainly the background foliage. Left click on the wheel to set the starting point in the greenish yellow area and right click on the green/light blue area to set the ending point. This makes it so pixels that are green in hue will be adjusted. Then drag the slider to make a change to the hue of these pixels. An example of this is shown below.

Pixels that were primarily green before have been hue shifted to purple

Notice that the toucan's hue has not changed, just the hue of the background pixels. The range can again be adjusted to do a different effect where we modify the toucan's beak by setting the range to the red and yellow sections of the image. This is shown below.

The toucan's beak has been made blue

In closing, the conditional hue adjustment can be used to do simple hue shifts on certain portions of the image. Images with objects of a solid hue and overall high hue contrast are good candidates for this effect