Working with Tools in Paint Shop Pro 8 - Match Mode, Tolerance and Opacity
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The purpose of the match mode options is to inform PSP how to evaluate the pixels that surround the one you clicked. This way, during a flood fill operation, PSP can determine how far the flooding is supposed to extend, and where the boundaries are that stop the flood. Here are the settings you can select and what they mean:
RGB Value. Only pixels with the same RGB value (the same amount of red, green, and blue) as the pixel you click are changed.
Color. Only pixels with the same hue and saturation values as the pixel you click are changed.
Hue. Only pixels with the same hue value as the pixel you click are changed.
Brightness. Only pixels with the same luminance (brightness) value as the pixel you click are changed.
All Opaque. Only pixels that are not transparent are changed. A transparent pixel on one layer reveals part of the contents of other layers beneath it; so any pixels where transparency applies remain unaltered.
Opacity. Only pixels with the same opacity are changed.
None. All pixels are changed.
Tolerance
After you've selected a match mode, the Tolerance setting comes into play. Here, 100 means "total forgiveness" of any differences between the pixel you click and neighboring pixels, 0 means no differences are tolerated (neighboring pixels must be exactly the same to be affected), and 50 is in between—for instance, if the fill starts on a red point, PSP might change an orange neighbor but not a green one.
Key Term:Neighboring pixels—Pixels that physically touch each other. When trying to judge which pixels will be affected by a change, only pixels that match the criteria and that touch the original pixel you click or another matching pixel are included.
Opacity
The Opacity setting is a percentage representing the extent to which new paint covers up the old paint. Think of opacity as transparency in reverse; when you set Opacity to less than 100, you're "watering down" your paint. With the Flood Fill tool, you can use Opacity to change the amount that the fill color replaces the qualified pixels (those your match mode and Tolerance settings indicate are to be flooded over). For example, if you set Opacity to 40, 60% of the pixel's original color is blended with 40% of your tool's color. More precisely, imagine the original pixel reduced to 60% intensity, and then blended with your tool's color at 40% intensity.
With the Airbrush tool, the Opacity setting controls the speed at which paint flows through the nozzle, as it were. Set to 100%, the airbrush completely covers the area you're pointing to with your chosen color, although along the edges of the airbrush path, you'll notice some fuzziness. But when you set Opacity to a much lesser number, such as 25%, paint "flows" more slowly from the nozzle, and the speed at which you paint becomes a factor. The longer you hold the airbrush over a spot, the more that spot becomes covered over by your paint; if you hold it at one spot for a few moments, eventually the area is entirely covered.
Note - A separate setting for the Airbrush tool called Rate also affects the flow of paint.
This chapter is from Paint Shop Pro 8, by Jennifer Fulton, (Sams, 2004, ISBN: 0672323893). Check it out at your favorite bookstore today.
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