Index: trunk/pswarp/src/pswarpTransformReadout.c
===================================================================
--- trunk/pswarp/src/pswarpTransformReadout.c	(revision 27096)
+++ trunk/pswarp/src/pswarpTransformReadout.c	(revision 28006)
@@ -148,5 +148,5 @@
     psThreadJob *job = NULL;
     int xMin = output->image->numCols, xMax = 0, yMin = output->image->numRows, yMax = 0; // Bounds
-    int goodPixels = 0;                 // total number of good pixels across all tiles
+    int goodPixels = psMetadataLookupS32(&mdok, output->analysis, PSWARP_ANALYSIS_GOODPIX); // Number of pixels
     psList *covariances = psMetadataLookupPtr(&mdok, output->analysis,
                                               PSWARP_ANALYSIS_COVARIANCES); // Collection of covar. matrices
@@ -157,4 +157,9 @@
         psFree(covariances);            // Drop reference; still have the copy on the analysis metadata
     }
+    double jacobian = psMetadataLookupF64(&mdok, output->analysis, PSWARP_ANALYSIS_JACOBIAN); // Jacobian
+    if (!isfinite(jacobian)) {
+        jacobian = 0.0;
+    }
+
     while ((job = psThreadJobGetDone()) != NULL) {
         if (job->args->n < 1) {
@@ -171,8 +176,16 @@
                 psListAdd(covariances, PS_LIST_TAIL, args->covariance);
             }
+            if (args->goodPixels > 0 && isfinite(args->jacobian)) {
+                jacobian += args->jacobian * args->goodPixels;
+            }
         }
         psFree(job);
     }
     psFree(grid);
+
+    psMetadataAddS32(output->analysis, PS_LIST_TAIL, PSWARP_ANALYSIS_GOODPIX, PS_META_REPLACE,
+                     "Number of good pixels", goodPixels);
+    psMetadataAddF64(output->analysis, PS_LIST_TAIL, PSWARP_ANALYSIS_JACOBIAN, PS_META_REPLACE,
+                     "Jacobian of transformation", jacobian);
 
     if (xMin < xMax && yMin < yMax) {