Documentation - Colors and Blenders
Several parts of this documentation refer to Blenders, Color
Blenders, or Blending Mode. They are all discussed here.
A list of blenders that Pocket Artist supports is in the image
to the right. Blenders are a way of mixing two colors to
provide a new one. They can be simple (such as the Normal blender, in which
the color on top replaces the color on the bottom), to
complex (such as the Overlay blender, which involves several
factors, overall giving the appearance of a colored transparency overlay.
Below are descriptions of the blenders. In the descriptions, two
picture layers are assumed (much like when you have a floating selection
ontop of a document -- they both have color data and a blender can
be associated with them). The blenders that the painting tools utilize
can be pictured as having a layer of a solid color (the foreground color)
ontop of the picture you are painting on.
Normal: this blender is the easiest, and simply involves
replacing the bottom color with the top color.
Multiply: this takes the two color values (on a 0 to 1 scale) and multiplies them
together, yielding something darker than the original (since two numbers
between 0 and 1 multiplied together is always smaller).
Screen: this is somewhat the inverse of multiplication, yet a little
different. It is not quite division, but the resulting color is always brighter
than the two colors that combine to form it.
Overlay: this is a complicated blender that combines both Multiply and
Screen to form a blending mode that acts as if the top layer is like a color
transparency that overlays ontop of the bottom layer.
Hard Light: this blender acts as if it is providing the lighting for
the bottom layer. It blends the two colors by having the top layer "light up"
the bottom colors.
Darken: this simple blender yields a color that is the minimum of the
Lighten: the opposite of darken, this blender take two colors and outputs
Difference: this blender takes two colors and computes the absolute value
of their difference, and results in that. Therefore, large color differences
are seen as brighter, and where colors are more similiar, the result is darker.
Exclusion: this blender is somewhat like Difference, yet when the
top and bottom colors approach the same value, the result is grayish instead
Hue: this blender takes the hue of the top color (that is, Red, Yellow,
Cyan, etc.) and makes the bottom color have the same Hue. It retains the
saturation (how "rich" the color is, or how "washed out" it looks) and its luminosity
(how bright it is).
Color: this blender takes the hue and saturation of the top color
and makes the bottom color have these same values.
Saturation: this blender makes the bottom color have the same saturation (richness)
as the top color.
Luminosity: this blender makes the bottom layer have the same
luminosity (brightness) of the top layer.