PhotoPlus X2 User Guide - Serif

Extracting part of an image
Manipulating Images 67
The Extract feature (Photo Studio toolbar) simplifies the task of isolating one
portion of a layer. You simply brush an outline around the edges of a region you
want to extract from the rest of the image, then mark a "foreground" area to be
retained—usually inside the outline. PhotoPlus applies sophisticated edge
detection within the marked edge band, decides which pixels to keep, and turns the
rest transparent, with variable blending along the edge. In preview mode, you can
fine-tune and reapply the extraction settings, and manually touch up the image
until the result is just right.
Instead of marking a foreground region, you can designate a specific "key" colour
to which edge pixels can be compared. Similar pixels will be kept, and dissimilar
pixels discarded. (See PhotoPlus help for details).
Using Channels
It goes without saying that every colour photo that you use in PhotoPlus will have
channels associated with it. For the colour mode RGB, the individual channels Red
(R), Green (G) and Blue (B) make up a composite RGB channel. Alternatively,
channels can also be separate, i.e. as their individual colours—Red, Green and
Blue. Each channel stores that particular colour’s information which, when
combined with the other channels, brings about the full colour image.
Within PhotoPlus, the use of multiple layers could possibly confuse the user with
respect to understanding channels. What do the channels refer to? —the entire
photo, part of it, or just the layer? The answer is simple—channels are always a
colour sub-set of the active selected layer, whether this is a background, standard,
shape or text layer. Remember that an imported photo will have a single
background layer by default.