User Guide

GNU Image Manipulation Program
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Dissolve mode dissolves the upper layer into the layer beneath it by drawing a random pattern of pixels in areas of partial
transparency. It is useful as a layer mode, but it is also often useful as a painting mode.
This is especially visible along the edges within an image. It is easiest to see in an enlarged screenshot. The image on the
left illustrates ‘Normal’ layer mode (enlarged) and the image on the right shows the same two layers in ‘Dissolve’ mode,
where it can be clearly seen how the pixels are dispersed.
Multiply
Figure 8.10: Example for layer mode ‘Multiply’
(a) Mask 1 is used as upper layer with 100% opac-
ity.
(b) Mask 2 is used as upper layer with 100% opac-
ity.
Multiply mode multiplies the pixel values of the upper layer with those of the layer below it and then divides the result by
255. The result is usually a darker image. If either layer is white, the resulting image is the same as the other layer (1 * I =
I). If either layer is black, the resulting image is completely black (0 * I = 0).
The equation is:
E =
1
255
(M ∗ I)
EQUATION 8.3: Equation for layer mode Multiply
The mode is commutative; the order of the two layers doesn’t matter.
Divide