User Guide

GNU Image Manipulation Program
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also be useful for giving images an embossed appearance. It subtracts the pixel value of the upper layer from that of the
lower layer and adds 128.
The equation is:
E = I − M + 128
EQUATION 8.13: Equation for layer mode Grain extract
Grain merge
Figure 8.19: Example for layer mode ‘Grain merge’
(a) Mask 1 is used as upper layer with 100% opac-
ity.
(b) Mask 2 is used as upper layer with 100% opac-
ity.
Grain merge mode merges a grain layer (possibly one created from the ‘Grain extract’ mode) into the current layer, leaving
a grainy version of the original layer. It does just the opposite of ‘Grain extract’. It adds the pixel values of the upper and
lower layers together and subtracts 128.
The equation is:
E = I + M − 128
EQUATION 8.14: Equation for layer mode Grain merge
Difference