Changeset 13957 for trunk/ppMerge/src/ppMergeScaleZero.c

Timestamp:

Jun 22, 2007, 1:42:25 PM (19 years ago)

Author:

eugene

Message:

added a comment explaining some subtleties of dark correction

File:

• trunk/ppMerge/src/ppMergeScaleZero.c (modified) (1 diff)

trunk/ppMerge/src/ppMergeScaleZero.c

@@ -199 +199 @@
                         view->chip = j;
                         view->cell = k;
+
+                        // This step applies the dark exptime / background relationship: F =
+                        // polymomial(exptime).  Below, the input images are scaled by the
+                        // output of this relationship.
+
+                        // For devices with linear dark and no residual bias, this relationship
+                        // is not defined in the configuration system, and the transformation
+                        // is defined (when loaded by the concepts) to be F = exptime.  Thus,
+                        // in this case, the resulting dark image consists of counts/sec.
+
+                        // For devices with a different relationship, the transformation yields
+                        // the expected number of counts in the given exposure, based on the
+                        // recorded exptime.  Thus, in this case, the resulting dark image
+                        // should have a median value of 1.0.
+
+                        // note that these corrections must be applied differently when used to
+                        // correct a science image.  
+
                         darktime->data.F32[i][cellNum] = pmFPADarkNorm(fpa, view,
                                                                        darktime->data.F32[i][cellNum]);