Grayscale Dialog Box

This dialog box is used to convert an image to black and white (grayscale). Normally you'll want to leave all three component check boxes checked; if you uncheck a component, it will not be used in determining the final gray brightness. For example, if you uncheck "Blue", then anything blue will turn out black or very dark, while things that are not blue may actually appear brighter.

You can exclude certain colors or pixels from being grayscaled by choosing "Exclude hue" or "Exclude lumination" and selecting the range you want protected by dragging with your mouse. For example, in the diagram, the range of colors that look green are selected. When you click "Apply", then, anything that is a shade of green will not be grayscaled. Similarly, you can also protect colors of a range of brightnesses using the "exclude lumination" bar.

You can also exclude more than one range of colors by holding using the Control, Alt and Shift keys on the keyboard

This exclusion feature is useful for doing those grayscale effects you see on TV where some objects are color and some are black and white. For example, if you want to show a person in color but his surroundings in black-and-white, you could select all the hues used by skin (for a white person, from red to yellow and sometimes a few other spots on the spectrum.) Generally, some other things on the image are preserved that you don't want to be, so you would probably select individual parts of the image and greyscale them without any exclusions.