[pktools] 127/375: added faq_pksetmask.dox with question from Giuseppe on 20130814

[Bas Couwenberg]

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sebastic-guest pushed a commit to branch upstream-master
in repository pktools.

commit 1f5545d55887aa89279a8cd806f7e192ab8889ef
Author: Pieter Kempeneers <kempenep at gmail.com>
Date:   Thu Aug 29 16:30:53 2013 +0200

    added faq_pksetmask.dox with question from Giuseppe on 20130814
---
 doc/examples_pksetmask.dox | 3 +--
 doc/faq_pksetmask.dox      | 8 ++++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/doc/examples_pksetmask.dox b/doc/examples_pksetmask.dox
index d12e580..8c09eff 100644
--- a/doc/examples_pksetmask.dox
+++ b/doc/examples_pksetmask.dox
@@ -12,7 +12,7 @@ copy values from input.tif to output.tif, but set all values to 255 if mask is n
 \code
 pksetmask -i input.tif -m mask1.tif -m mask2.tif -o output.tif -ot Byte -t 0 -f 255
 \endcode
-copy pixel values from input.tif to output.tif, applying two masks, setting all values to 255 where either mask is 0.
+Application of two masks. Copy pixel values from input.tif to output.tif, setting all values to 255 where either mask is 0.
 
 \code
 pksetmask -i input.tif -m mask.tif -o output.tif -ot Byte -t 0 -t 1 -f 255 -f 255
@@ -23,4 +23,3 @@ copy pixel values from input.tif to output.tif, applying single masks, setting a
 pksetmask -i input.tif -m mask.tif -o output.tif -ot Byte -t 0 -t 1 -f 255 -f 255
 \endcode
 copy pixel values from input.tif to output.tif, applying single masks, setting all values to 255 where mask is either 0 or 1.
-
diff --git a/doc/faq_pksetmask.dox b/doc/faq_pksetmask.dox
new file mode 100644
index 0000000..f87e284
--- /dev/null
+++ b/doc/faq_pksetmask.dox
@@ -0,0 +1,8 @@
+\section faq_pksetmask Frequently asked questions about pksetmask
+
+ Q1. I want to mask my input image (a byte image with values between 0 and 254) with a mask that only covers a spatial subset of the input image. Within the spatial subset of the primary mask, all pixels must be set to 0 where the primary mask equals 1. Outside the spatial subset I want to set all pixel values to 255.
+
+ A1. This can be done using two masks, selecting the input image as the secondary mask. Choose the secondary operator acting on the secondary mask such that the condition is always true (e.g, < 255 ).
+\code
+pksetmask -i input.tif -m mask.tif -t 1 -f 0 --operator '='  -m input.tif -t 255 -f 255 --operator '<'  -o output.tif
+\endcode

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