Changeset 4872 for trunk/doc/pslib/psLibSDRS.tex

Timestamp:

Aug 24, 2005, 1:50:27 PM (21 years ago)

Author:

Paul Price

Message:

Clarifying psRegion conventions

File:

• trunk/doc/pslib/psLibSDRS.tex (modified) (3 diffs)

trunk/doc/pslib/psLibSDRS.tex

@@ -1 @@
-%%% $Id: psLibSDRS.tex,v 1.327 2005-08-24 21:57:49 price Exp $
+%%% $Id: psLibSDRS.tex,v 1.328 2005-08-24 23:50:27 price Exp $
 \documentclass[panstarrs,spec]{panstarrs}
 
@@ -3550 +3550 @@
 \code{psRegion} shall do so by value, not by pointer.
 
+All functions which use a \code{psRegion} must interpret the
+definition of $(x0,y0)$ and $(x1,y1)$ in the same way.  The coordinate
+$(x0,y0)$ defines the starting pixel in the region.  The coordinate
+$(x1,y1)$ defines the outer bound of the region, and are NOT included
+in the region.  The size of the region is $(x1-x0,y1-y1)$.  If either
+$x1$ or $y1$ is less than or equal to 0, the value is added to the
+image dimensions (e.g., $Nx + x1$).  Thus a region \code{[0:0,0:0]}
+refers to the full image array, while \code{[0:-10,0:-20]} refers to
+the entire image, minus the last 10 columns and the last 20 rows.
+
 We define two functions to set and return the value of a
 \code{psRegion}.  The first defines the region by the corner
@@ -3565 +3575 @@
 \end{prototype}
 
-All functions which use a psRegion must interpret the definition of
-$(x0,y0)$ and $(x1,y1)$ in the same way. The coordinate $(x0,y0)$
-defines the starting pixel in the region.  The coordinate $(x1,y1)$
-defines the outer bound of the region.  The size of the region is
-$(x1-x0,y1-y1)$.  If either $x1$ or $y1$ is less than or equal to 0,
-the value is added to the image dimensions ($Nx + x1$).  Thus a region
-\code{[0:0,0:0]} refers to the full image array, while
-\code{[0:-10,0:-20]} trims the last 10 columns and the last 20 rows.
+{\bf Note that regions specified by strings are in the FITS standard.}
+It is the responsibility of \code{psRegionFromString} and
+\code{psRegionToString} to convert between the PS standard (0 means
+first pixel; upper value is not included, but lower is) and the FITS
+standard (1 means first pixel; lower and upper values are included),
+which simply involves subtracting one from \code{x0} and \code{y0}
+when going from a string representation to a \code{psRegion}.
 
 \begin{prototype}