Slider

A slider is a control used to specify either one or two numbers. Sliders are used by many different transformations and are also integral to the Amount Control.

There are two forms of sliders: the single slider for entering one number and the double slider for entering two numbers. Both types include of a single line of text called a readout that describes what parameter is being adjusted by the slider and what its current value is. Below the readout is a scale with a marker at the current slider value. A single slider has one white marker -- a double slider has a white marker above the scale and a black marker below it.

Here are some examples of sliders from the Bilateral Sharpen transformation:

Single Slider

Double Slider

In most cases, resizing the transformation dialog box also resizes its sliders -- longer sliders are easier to adjust.

Adjusting Sliders

To adjust the value of a single slider, click anywhere along the scale to set the marker to that location and, if necessary, drag the marker left or right until you reach the desired value. The readout is updated as you move the marker. Adjusting a double slider is the same except you click either above or below the scale center line to set the white marker or the black marker -- the two markers move independently.

Fine Tuning

The method above is good for quick but coarse slider adjustments, but it can be tricky to get exactly the value you want. To make fine adjustments to the location of a marker, hold the Shift key down while dragging the marker left or right. The increases the resolution by a factor of 16, giving you very precise control over the slider setting at the expense of reduced range of motion. So, use coarse adjustment to get close and then hold down Shift to make any necessary final tweaks.

Another way to adjust sliders in small increments is the hold the Ctrl key down while clicking on the slider. This bumps the slider 4 pixels to the right or to the left, depending on whether you click to the right or left of the current position. If you hold down both Ctrl and Shift while clicking, the slider is moved by 1 pixel instead. This lets you make small changes to a slider without have to take your eyes off of the image being adjusted. If you make the slider longer by resizing the transformation dialog box, the slider value changes by a smaller amount per click since a pixel becomes a smaller fraction of the slider width.