From: Good Guy <good1.2guy@gmail.com>
Date: Tue, 8 Feb 2022 00:04:30 +0000 (-0700)
Subject: add masks need Alpha channel
X-Git-Tag: 2022-02~3
X-Git-Url: https://git.cinelerra-gg.org/git/?a=commitdiff_plain;h=6da2f169fab398a313d2710a4040393ef491705b;p=goodguy%2Fcin-manual-latex.git

add masks need Alpha channel
---

diff --git a/parts/Windows.tex b/parts/Windows.tex
index 760a696..1d618ac 100644
--- a/parts/Windows.tex
+++ b/parts/Windows.tex
@@ -1100,6 +1100,8 @@ The compositing pipeline graph has a masking stage (figure~\ref{fig:temporary-02
 
 The Mask popup menu can be overwhelming upon first encounter.  However, if you follow the next
 few steps you can create a single simple mask without having to understand every possible parameter.
+Be sure you are working in a Format that includes the Alpha channel, YUVA or RGBA, because you need
+to have transparency for masking to show or will end up with only a black area.
 \begin{enumerate}
     \item To define a mask, in the Compositor window click on the \textit{Edit mask} icon to get the popup Mask menu.  If the menu does not come up, click on the \textit{Show tool info}.
     \item  On the video, LMB click on the place where you want to start a mask.