Index: trunk/doc/pslib/psLibSDRS.tex
===================================================================
--- trunk/doc/pslib/psLibSDRS.tex	(revision 6371)
+++ trunk/doc/pslib/psLibSDRS.tex	(revision 6434)
@@ -1,3 +1,3 @@
-%%% $Id: psLibSDRS.tex,v 1.382 2006-02-08 03:26:01 jhoblitt Exp $
+%%% $Id: psLibSDRS.tex,v 1.383 2006-02-16 18:57:51 eugene Exp $
 \documentclass[panstarrs,spec]{panstarrs}
 
@@ -3690,5 +3690,17 @@
 limits.  The output of this function is always a valid region, though
 it may define an area of 0 pixels.  If \code{image} is a subimage, the
-region coordinates refer to the subimage pixel coordinates.
+input and output region coordinates refer to the parent pixel
+coordinates.  The only exception to this statement is that the
+negative limits should be applied to the upper limits of the subimage,
+not the parent.  Thus, if we have an input subimage with
+\code{col0,row0} of (10,20), and \code{numCols,numRows} of 1000,1000
+(implying parent image dimensions of at least 1010,1020), we would
+have the following conversions:
+\begin{verbatim}
+(50:100,50:100) -> (50:100,50:100)   : no change (region within image)
+(0:0,0:0)       -> (10:1010,20:1020) : upper and lower limits constrained 
+(5:-5,5:-5)     -> (10:1005,20:1015)
+(5:1020,5:1020) -> (10:1010,20:1020)
+\end{verbatim}
 
 \begin{prototype}
@@ -5083,4 +5095,6 @@
 \subsubsection{Image Structure Manipulation}
 
+\tbd{clarify that subset and trim regions are in the *parent* coords}
+
 \begin{prototype}
 psImage *psImageSubset(psImage *image, psRegion region);
@@ -5095,9 +5109,12 @@
 In the event that \code{x1} or \code{y1} are negative, they shall be
 interpreted as being relative to the size of the parent image in that
-dimension.  The entire subraster must be contained within the raster
-of the parent image.  Note that the \code{refCounter} for the parent
-should be incremented.  This function must be defined for the
-following types: \code{psU8}, \code{psU16}, \code{psS8}, \code{psS16},
-\code{psF32}, \code{psF64}, \code{psC32}, \code{psC64}.
+dimension.  If the input image is a subimage, the region coordinates
+refer to the \em{parent} pixel coordinates.  The entire subraster must
+be contained within the raster of the parent image.  Note that the
+\code{refCounter} for the parent should be incremented.  This function
+must be defined for the following types: \code{psU8}, \code{psU16},
+\code{psS8}, \code{psS16}, \code{psF32}, \code{psF64}, \code{psC32},
+\code{psC64}.  \tbd{allow this function to saturate on the edges like
+psRegionForImage?}
 
 \begin{prototype}
@@ -5132,4 +5149,6 @@
 
 \subsubsection{Image Pixel Extractions}
+
+\tbd{clarify that subset and trim regions are in the *parent* coords}
 
 \begin{datatype}
@@ -5418,5 +5437,5 @@
 region) results in a return value of -1.  The \code{region} refers to
 the pixels of the \code{mask}; if \code{mask} is a subimage, the
-region must be defined relative to those subimage pixels.
+region must be defined relative to the parent pixel coordinate.
 
 \begin{prototype}