Release 10.78.02

git-svn-id: http://svn.code.sf.net/p/netpbm/code/advanced@2950 9d0c8265-081b-0410-96cb-a4ca84ce46f8

3 files changed, 27 insertions, 11 deletions

diff --git a/doc/HISTORY b/doc/HISTORY
index d45b2baf..707256a6 100644
--- a/doc/HISTORY
+++ b/doc/HISTORY
@@ -4,6 +4,16 @@ Netpbm.
 CHANGE HISTORY 
 --------------
 
+17.04.15 BJH  Release 10.78.02
+
+              pamcomp: fix incorrect output with -mixtransparency.
+              Always broken.  (-mixtransparency was new in Netpbm 10.56,
+              September 2011).
+
+              pamcomp: remove debug trace message with -mixtransparency.
+              Always broken.  (-mixtransparency was new in Netpbm 10.56,
+              September 2011).
+
 17.04.04 BJH  Release 10.78.01
 
               pnmtojpeg: fix array bounds violation in argument list.  Always
diff --git a/editor/pamcomp.c b/editor/pamcomp.c
index 548882e3..35117fbe 100644
--- a/editor/pamcomp.c
+++ b/editor/pamcomp.c
@@ -438,6 +438,13 @@ computeOverlayPosition(int                const underCols,
    overlaying images are plastic slides and we taped them together to make a
    composed plastic slide, the calculations go as follows.
 
+   U means color of underlay pixel
+   O means color of overlay pixel
+   C means color of composed pixel
+   X is a variable, standing for U, O, or C
+   X_T means transparency of the X pixel
+   X_O means opacity of the X pixel
+
    Opacity and transparency are fractions in [0,1] and are complements:
 
      X_T = 1 - X_O
@@ -481,23 +488,24 @@ static sample
 composeComponents(sample           const compA, 
                   sample           const compB,
                   float            const distrib,
-                  float            const aFactor,
+                  float            const bFactor,
                   float            const composedFactor,
                   sample           const maxval,
                   enum sampleScale const sampleScale) {
 /*----------------------------------------------------------------------------
   Compose a single color component of each of two pixels, with 'distrib' being
   the fraction of 'compA' in the result, 1-distrib the fraction of 'compB'.
-  Note that this does not apply to an opacity component.
+
+  Note that this function is not useful for an opacity component.
 
   'sampleScale' tells in what domain the 'distrib' fraction applies:
   brightness or light intensity (gamma-adjusted or not).
 
-  'aFactor' is a factor in [0,1] to apply to 'compA' first.
+  'bFactor' is a factor in [0,1] to apply to 'compB' first.
 
   'composedFactor' is a factor to apply to the result.
 
-  See above for explanation of why 'aFactor' and 'composedFactor' are
+  See above for explanation of why 'bFactor' and 'composedFactor' are
   useful.
 
   The inputs and result are based on a maxval of 'maxval'.
@@ -508,22 +516,22 @@ composeComponents(sample           const compA,
 -----------------------------------------------------------------------------*/
     sample retval;
 
-    if (fabs(distrib) > .999 && aFactor > .999 && composedFactor > .999)
+    if (fabs(distrib) > .999 && bFactor > .999 && composedFactor > .999)
         /* Fast path for common case */
         retval = compA;
     else {
         if (sampleScale == INTENSITY_SAMPLE) {
             sample const mix = 
-                ROUNDU(compA * aFactor * distrib + compB * (1.0 - distrib));
+                ROUNDU(compA * distrib + compB * bFactor *(1.0 - distrib));
             retval = MIN(maxval, MAX(0, mix));
         } else {
             float const compANormalized = (float)compA/maxval;
             float const compBNormalized = (float)compB/maxval;
             float const compALinear = pm_ungamma709(compANormalized);
             float const compBLinear = pm_ungamma709(compBNormalized);
-            float const compALinearAdj = compALinear * aFactor;
+            float const compBLinearAdj = compBLinear * bFactor;
             float const mix = 
-                compALinearAdj * distrib + compBLinear * (1.0 - distrib)
+                compALinear * distrib + compBLinearAdj * (1.0 - distrib)
                 * composedFactor;
             sample const sampleValue = ROUNDU(pm_gamma709(mix) * maxval);
             retval = MIN(maxval, MAX(0, sampleValue));
@@ -556,8 +564,6 @@ composedOpacity(tuple         const uTuple,
         float const composedTrans = underlayTrans * overlayTrans;
         sample const sampleValue =  (1.0 - composedTrans) * cPamP->maxval;
         retval = MIN(cPamP->maxval, MAX(0, sampleValue));
-        pm_message("underlay = %lu/%f, overlay = %f, composed = %f",
-                   uTuple[uPamP->opacity_plane],underlayTrans, overlayTrans, composedTrans);
     } break;
     case AM_KEEPUNDER:
         retval = uTuple[uPamP->opacity_plane];
diff --git a/version.mk b/version.mk
index e0f87ef3..671c59a4 100644
--- a/version.mk
+++ b/version.mk
@@ -1,3 +1,3 @@
 NETPBM_MAJOR_RELEASE = 10
 NETPBM_MINOR_RELEASE = 78
-NETPBM_POINT_RELEASE = 1
+NETPBM_POINT_RELEASE = 2