Index: /trunk/psModules/src/camera/Makefile.am
===================================================================
--- /trunk/psModules/src/camera/Makefile.am	(revision 11123)
+++ /trunk/psModules/src/camera/Makefile.am	(revision 11124)
@@ -24,5 +24,6 @@
 	pmFPAfileFitsIO.c \
 	pmFPAFlags.c \
-	pmFPALevel.c
+	pmFPALevel.c \
+	pmFPAExtent.c
 
 pkginclude_HEADERS = \
@@ -47,5 +48,6 @@
 	pmFPAfileFitsIO.h \
 	pmFPAFlags.h \
-	pmFPALevel.h
+	pmFPALevel.h \
+	pmFPAExtent.h
 
 CLEANFILES = *~
Index: /trunk/psModules/src/camera/pmFPAExtent.c
===================================================================
--- /trunk/psModules/src/camera/pmFPAExtent.c	(revision 11124)
+++ /trunk/psModules/src/camera/pmFPAExtent.c	(revision 11124)
@@ -0,0 +1,128 @@
+#include <stdio.h>
+#include <pslib.h>
+
+#include "pmFPA.h"
+
+psRegion *pmReadoutExtent(const pmReadout *readout)
+{
+    PS_ASSERT_PTR_NON_NULL(readout, NULL);
+
+    if (readout->image) {
+        return psRegionAlloc(readout->col0, readout->image->numCols,
+                             readout->row0, readout->image->numRows);
+    }
+    pmCell *cell = readout->parent;     // The parent cell
+    if (!cell) {
+        psError(PS_ERR_UNEXPECTED_NULL, true, "Unable to determine size of readout.\n");
+        return NULL;
+    }
+    bool mdok;                          // Status of MD lookup
+    psRegion *trimsec = psMetadataLookupPtr(&mdok, cell->concepts, "CELL.TRIMSEC"); // Trim section
+    if (!mdok || !trimsec) {
+        psError(PS_ERR_UNKNOWN, true, "Unable to find CELL.TRIMSEC.\n");
+        return NULL;
+    }
+
+    // XXX: Binning?
+
+    return psRegionAlloc(readout->col0, trimsec->x1 - trimsec->x0,
+                         readout->row0, trimsec->y1 - trimsec->y0);
+}
+
+
+psRegion *pmCellExtent(const pmCell *cell)
+{
+    PS_ASSERT_PTR_NON_NULL(cell, NULL);
+
+    psArray *readouts = cell->readouts; // Array of component readouts
+    psRegion *cellExtent = psRegionAlloc(INFINITY, 0, INFINITY, 0); // Extent of cell
+    for (long i = 0; i < readouts->n; i++) {
+        pmReadout *readout = readouts->data[i]; // Readout of interest
+        psRegion *roExtent = pmReadoutExtent(readout); // Extent of readout
+        cellExtent->x0 = PS_MIN(cellExtent->x0, roExtent->x0);
+        cellExtent->x1 = PS_MAX(cellExtent->x1, roExtent->x1);
+        cellExtent->y0 = PS_MIN(cellExtent->y0, roExtent->y0);
+        cellExtent->y1 = PS_MAX(cellExtent->y1, roExtent->y1);
+        psFree(roExtent);
+    }
+
+    bool mdok;                          // Status of MD lookup
+    int x0 = psMetadataLookupS32(&mdok, cell->concepts, "CELL.X0"); // Cell x offset
+    if (!mdok) {
+        psError(PS_ERR_UNKNOWN, true, "Unable to find CELL.X0.\n");
+        psFree(cellExtent);
+        return NULL;
+    }
+    int y0 = psMetadataLookupS32(&mdok, cell->concepts, "CELL.Y0"); // Cell y offset
+    if (!mdok) {
+        psError(PS_ERR_UNKNOWN, true, "Unable to find CELL.Y0.\n");
+        psFree(cellExtent);
+        return NULL;
+    }
+
+    cellExtent->x0 += x0;
+    cellExtent->x1 += x0;
+    cellExtent->y0 += y0;
+    cellExtent->y1 += y0;
+
+    return cellExtent;
+}
+
+
+psRegion *pmChipExtent(const pmChip *chip)
+{
+    PS_ASSERT_PTR_NON_NULL(chip, NULL);
+
+    psArray *cells = chip->cells;       // Arrya of component cells
+    psRegion *chipExtent = psRegionAlloc(INFINITY, 0, INFINITY, 0); // Extent of chip
+    for (long i = 0; i < cells->n; i++) {
+        pmCell *cell = cells->data[i];  // Cell of interest
+        psRegion *cellExtent = pmCellExtent(cell); // Extent of cell
+        chipExtent->x0 = PS_MIN(chipExtent->x0, cellExtent->x0);
+        chipExtent->x1 = PS_MAX(chipExtent->x1, cellExtent->x1);
+        chipExtent->y0 = PS_MIN(chipExtent->y0, cellExtent->y0);
+        chipExtent->y1 = PS_MAX(chipExtent->y1, cellExtent->y1);
+        psFree(cellExtent);
+    }
+
+    bool mdok;                          // Status of MD lookup
+    int x0 = psMetadataLookupS32(&mdok, chip->concepts, "CHIP.X0"); // Chip x offset
+    if (!mdok) {
+        psError(PS_ERR_UNKNOWN, true, "Unable to find CHIP.X0.\n");
+        psFree(chipExtent);
+        return NULL;
+    }
+    int y0 = psMetadataLookupS32(&mdok, chip->concepts, "CHIP.Y0"); // Chip y offset
+    if (!mdok) {
+        psError(PS_ERR_UNKNOWN, true, "Unable to find CHIP.Y0.\n");
+        psFree(chipExtent);
+        return NULL;
+    }
+
+    chipExtent->x0 += x0;
+    chipExtent->x1 += x0;
+    chipExtent->y0 += y0;
+    chipExtent->y1 += y0;
+
+    return chipExtent;
+}
+
+
+psRegion *pmFPAExtent(const pmFPA *fpa)
+{
+    PS_ASSERT_PTR_NON_NULL(fpa, NULL);
+
+    psArray *chips = fpa->chips;       // Arrya of component chips
+    psRegion *fpaExtent = psRegionAlloc(INFINITY, 0, INFINITY, 0); // Extent of fpa
+    for (long i = 0; i < chips->n; i++) {
+        pmChip *chip = chips->data[i];  // Chip of interest
+        psRegion *chipExtent = pmChipExtent(chip); // Extent of chip
+        fpaExtent->x0 = PS_MIN(fpaExtent->x0, chipExtent->x0);
+        fpaExtent->x1 = PS_MAX(fpaExtent->x1, chipExtent->x1);
+        fpaExtent->y0 = PS_MIN(fpaExtent->y0, chipExtent->y0);
+        fpaExtent->y1 = PS_MAX(fpaExtent->y1, chipExtent->y1);
+        psFree(chipExtent);
+    }
+
+    return fpaExtent;
+}
Index: /trunk/psModules/src/camera/pmFPAExtent.h
===================================================================
--- /trunk/psModules/src/camera/pmFPAExtent.h	(revision 11124)
+++ /trunk/psModules/src/camera/pmFPAExtent.h	(revision 11124)
@@ -0,0 +1,29 @@
+#ifndef PM_FPA_EXTENT_H
+#define PM_FPA_EXTENT_H
+
+/// Return the extent of a readout
+///
+/// The extent is determined from an image, if present, or the CELL.TRIMSEC otherwise.
+psRegion *pmReadoutExtent(const pmReadout *readout ///< The readout of interest
+                         );
+
+/// Return the extent of a cell
+///
+/// The extent is determined from the extent of the component readouts, plus CELL.X0,Y0
+psRegion *pmCellExtent(const pmCell *cell ///< The cell of interest
+                      );
+
+/// Return the extent of a chip
+///
+/// The extent is determined from the extent of the component cells, plus CHIP.X0,Y0
+psRegion *pmChipExtent(const pmChip *chip ///< The chip of interest
+                      );
+
+/// Return the extent of an FPA
+///
+/// The extent is determined from the extent of the component chips.
+psRegion *pmFPAExtent(const pmFPA *fpa ///< The FPA of interest
+                     );
+
+
+#endif