Selective Color Correction

The selective color correction control lets you specify a set of color corrections to be applied to an image.

Show Modified Color Wheel

When the Show Modified Color Wheel checkbox is checked, selective color correction is applied to the color wheel itself and the results of this are displayed in its place. This gives you a visual representation of which colors are being changed and by how much. To return to the normal color wheel display, uncheck the check box.

Color Wheel

The color wheel and the control points displayed over it are central to this control. A control point has two parts – an input color and an output color. If both are the same, the control point in displayed as a circle. If the output color differs from the input color, a smaller circle is displayed at the input color, connected by an arrow pointing to the output color. All colors in the input image whose hue and saturation match the input color are changed in the output image to the output color. Colors in between control points are interpolated to make a smooth transition.

The control point you most recently added or clicked on is called the current control point. The current control point, if any, is displayed as a filled square instead of a hollow circle. To make a control point the current control point, simply click on it.

Initially, there are 7 control points set on white, red, yellow, green, cyan, blue, and magenta. Each of these control points has both its input and output colors set the same. These control points ensure that white and the fully saturated primary and secondary colors in the input image are left unchanged in the output image, which is often a good starting point if you just want to make a minor change. Applying selective color correction with this initial configuration, however, will have no effect on the input image as none of the output colors differs from its input color.

To add a new control point, shift-click (hold down either Shift key while clicking with the left mouse button) on the color wheel at the desired input color location. Or, you can add a control point by using the Probe by clicking once on a color in the input image window you want to change. You can create up to 256 control points.

To remove a control point, control-click (hold down the either Ctrl key while clicking with the left mouse button) on it.

To change the output color of a control point, click and drag its circle on the color wheel. This will extend an arrow from the control point to the desired output color. Once an arrow has been created, you can make additional changes to the output color by dragging the arrowhead.

To change the input color of a control point, first make the output color different from the input color, if necessary. Then you can change the input color by dragging the small circle at the base of the arrow.

To select a control point, simply click on it. The selected control point is displayed on the color wheel as a filled square instead of a hollow circle.

 Zoom Tool Bar

The zoom buttons let you zoom in or out on the color wheel. When you zoom in, the color wheel is enlarged centered on the current control point, if any, and scroll bars are displayed next to the color wheel to let you move around. Zooming in makes it easier to make fine adjustments to the control points; zooming out lets you see more of the color wheel at once. You can zoom in a maximum of four levels.

Palette

A set of palette colors is displayed just below the color wheel. These colors represent the current custom palette as defined using the Palette Tool or the Color Picker. Clicking on a palette color inserts a new control point in the color wheel at the corresponding color. This feature is useful if you want to match a color from an image other than the current input image. To do this, first click on the image you want to select from, activate the palette tool and select the color, and then edit the image you want to perform selective color correction on and select the color from the palette.

Brightness Change

This control is hidden unless a control point is selected. Each control point has an associated color change as indicated by the size and direction of the arrow displayed on the color wheel. In addition, each control point also has an associated brightness change; positive settings make colors that match the input color of a control point brighter while negative values make matching colors darker (using the HSV or HSL color space).

The Brightness Change slider at the bottom of the Selective Color Correction control lets you assign brightness adjustments to the current control point. To make a control point the current control point, simply click on it. This value displayed in the slider is the value of the brightness change setting for the current control point -- any changes you make to the slider alter the brightness change setting for the current control point.

Settings Menu

Reset All

This command resets all the control points to their initial configuration.

Preserve Black and White/Preserve Black

These options relate to brightness corrections. When Preserve Black and White is selected (the default setting), brightness corrections are made in such a way as to leave pure black and pure white unchanged – the primary effect is on the mid-tones. When Preserve Black is selected, an equal percentage brightness increase is applied to all brightness levels. This provides a more uniform brightening effect but can lead to a loss of highlight detail. The type of brightness curves used is illustrated below.

HSV / HSL

These settings affect the color space used when the Brightness Change slider is used to lighten or darken colors.

Probe Size

These settings determine the size of the probe used to select colors for new control points. Larger probes are less sensitive to noise while smaller probes can select finer detail.

Tips

To make a correction of one color in an image, click on a part of the input image having the color you want to change. Next go to the color wheel and click and drag on the new control point you just created. To make the color more or less saturated, drag it toward the edge or toward the center of the color wheel. To adjust its hue, drag the control point either clockwise or counterclockwise about the center. To make further adjustments, click again on the input image to create additional control points.

If the transformation is changing colors close to one you selected and you want these to remain unchanged, create additional control points whose input and output colors are the same to prevent the nearby colors from being modified.

If there are several elements in the image that have the same color, and you only want to adjust some of them, create a mask to isolate the parts you want to change.