Dfx User Guide - Tiffen.com

236 Masks
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Mask Creation
Trimaps
EZ Mask creates masks by using a trimap--a pre-segmented image consisting
of three regions of foreground (what you want to isolate), background and
unknown. Partial opacity values are then computed only for pixels inside the
unknown region. Two trimap methods can be used: Stroke and Filled. When
creating masks, start with the Stroke method and move on to the Filled method
if the results are not satisfying.
Stroke
Unlike previous approaches, our trimaps can be relatively sparse consisting of
individual foreground and background brush strokes. All pixels left unmarked
will be treated as unknown. After processing, if any fine foreground details are
missing from the mask, the Unknown brush can be used in these areas to help
recover lost detail.
Strokes
Mask
Stroke trimaps require little user input, but when color ambiguity exists between
the foreground and background, a Filled trimap may create a more accurate
mask. In addition, Stroke trimaps will also take longer to render as they require
an extra calculation step.
Stroke Trimap Creation Tips & Tricks
• Make sure you place enough foreground and background strokes. A good stroke
technique is to draw an inner outline around the object you are extracting using
the Paint Foreground brush and an outer outline using the Paint Background
brush.
Dfx User Guide
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