Changeset 2034

Timestamp:

Oct 8, 2004, 2:35:09 PM (22 years ago)

Author:

Paul Price

Message:

Added pmReadoutCombine.

Location:

trunk/doc/modules

Files:

• ChangeLogSDRS.tex (modified) (2 diffs)
• ModulesSDRS.tex (modified) (4 diffs)

trunk/doc/modules/ChangeLogSDRS.tex

@@ -1 @@
-%%% $Id: ChangeLogSDRS.tex,v 1.2 2004-10-07 18:16:57 eugene Exp $
+%%% $Id: ChangeLogSDRS.tex,v 1.3 2004-10-09 00:35:02 price Exp $
 
 \subsection{Changes from version 00 to version 01}
@@ -10 +10 @@
 \item added \code{pmFPAfromHeader}
 \end{itemize}
+
+\subsection{Changes from version 01 to version 02}
+
+\begin{itemize}
+\item Added \code{pmReadoutCombine}
+\end{itemize}

trunk/doc/modules/ModulesSDRS.tex

@@ -1 @@
-%%% $Id: ModulesSDRS.tex,v 1.16 2004-10-07 18:15:06 eugene Exp $
+%%% $Id: ModulesSDRS.tex,v 1.17 2004-10-09 00:35:09 price Exp $
 \documentclass[panstarrs]{panstarrs}
 
@@ -10 +10 @@
 \project{Pan-STARRS Image Processing Pipeline}
 \organization{Institute for Astronomy}
-\version{01}
+\version{02}
 \docnumber{PSDC-430-008}
 % note the use of the docnumber & version number:
@@ -353 +353 @@
 image), the function shall generate an error.
 
+
+
+\section{Calibration}
+
+The calibration module essentially consists of combining multiple
+images of a particular type in order to build up signal-to-noise.  For
+this, we require a general purpose image combination module.  We
+forsee this module as only acting upon data from the same detector,
+and so each input image will have the same noise characteristics.
+
+\begin{verbatim}
+typedef struct {
+    psStats *stats;                     // Statistics to use in combining pixels
+    unsigned int maskVal,               // Mask pixels where mask & maskVal == 1
+    float fracHigh;                     // Fraction of high pixels to throw
+    float fracLow;                      // Fraction of low pixels to throw
+    int nKeep;                          // Number of pixels to be sure to keep
+} pmCombineParams;
+
+psImage *
+pmReadoutCombine(psImage *output,       // Output image, or NULL
+                 const psList *inputs,  // List of input readouts
+                 pmCombineParams *params, // Combination parameters
+                 const psVector *zero,  // Offsets to apply for each image
+                 const psVector *scale, // Scales to apply for each image
+                 bool applyZeroScale,   // Are zero and scale for application, or only noise properties?
+                 float gain,            // Gain in e/ADU
+                 float readnoise        // Read noise in e
+                 );
+\end{verbatim}
+
+\code{pmReadoutCombine} combines input images pixel by pixel --- for
+each pixel of the output image, a stack of contributing input pixels
+is formed and combined.  Several of its input parameters are lists or
+vectors, and if these are not all of the same length (or \code{NULL}),
+the module shall generate an error and return \code{NULL}.
+
+If the provided \code{output} is \code{NULL}, then the module shall
+allocate a new image of sufficient size for the input images.  If the
+\code{output} image is non-\code{NULL} and is not of sufficient size
+for the combined image, the module shall generate an error and return
+\code{NULL}.
+
+If the \code{inputs} is \code{NULL}, the module shall generate an
+error and return \code{NULL}.  Otherwise, the \code{inputs} shall be a
+list of \code{psReadout}s.  The images contained within the
+\code{psReadout}s need not all be of the same size, but the module
+shall take into account the offsets (\code{col0,row0}) from the corner
+of the detector when comparing pixels, so that it is the same
+\textit{physical} pixels that are combined.
+
+The parameters used in the combination, including how the pixels are
+to be combined, and how the rejection is performed is contained within
+the \code{params}, which may not be \code{NULL} (otherwise the module
+shall generate an error and return \code{NULL}).  We choose to use
+this structure instead of supplying the values separately in order to
+keep down the number of parameters to \code{pmReadoutCombine}; the
+\code{psCombineParams} may be recycled for subsequent calls to
+\code{pmReadoutCombine} since the values are not dependent upon the
+choice of inputs, but merely specify how the combination is to be
+performed.
+
+The particular statistic specified by \code{stats} shall be used to
+combine each stack of pixels from the input images.  Only one of the
+statistics choices may be specified, otherwise the module shall
+generate an error and return \code{NULL}.
+
+If the \code{maskVal} is non-zero, then pixels in the \code{mask} of
+each \code{psReadout} in the \code{inputs} which satisfy the
+\code{maskVal} shall not have the corresponding pixels placed in the
+stack for combination.
+
+After masking, but before performing the combination, the highest
+\code{fracHigh} fraction and lowest \code{fracLow} fraction of pixels
+in the stack are immediately rejected, unless this would leave less
+than \code{nKeep} pixels in the stack, in which case no immediate
+rejection is performed.
+
+If the \code{zero} vector is non-\code{NULL} and \code{applyZeroScale}
+is \code{true}, then the appropriate values shall be added to the
+\code{inputs} before combining.  In the event that the type of the
+\code{psVector} is more precise than that of any of the \code{inputs},
+the module shall generate a warning and truncate the sum to the
+precision of the image.  If \code{zero} is non-\code{NULL} and
+\code{applyZeroScale} is false, then the values shall only be used in
+calculating the noise.
+
+If the \code{scale} vector is non-\code{NULL} and
+\code{applyZeroScale} is \code{true}, then the appropriate values
+shall multiply the \code{inputs} before combining.  In the event that
+the type of the \code{psVector} is more precise than that of any of
+the \code{inputs}, the module shall generate a warning and truncate
+the multiplication to the precision of the image.  If \code{scale} is
+non-\code{NULL} and \code{applyZeroScale} is false, then the values
+shall only be used in calculating the noise.
+
+The purpose of \code{applyZeroScale} is to allow combination of fringe
+frames, where the frames have been deliberately sky-subtracted and
+rescaled (to get the fringes amplitudes running from -1 to 1), which
+actions should not be undone when combining, but yet it is desirable
+to provide the \code{zero} and \code{scale} values so that the correct
+noise properties are used in the combination.
+
+If the \code{gain} and \code{readnoise} are positive and non-negative
+(respectively), then these shall be used to provide weights for the
+combination.
+
+
+
 \section{Revision Change Log}
 \input{ChangeLogSDRS.tex}
@@ -607 +716 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-
 \begin{verbatim}
 char *pmCameraFromHeader (psFitsHeader *header);