From 6d06b8e0c26536edaedf04ae56849667b85c1325 Mon Sep 17 00:00:00 2001
From: giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8>
Date: Sun, 20 Jan 2019 19:22:55 +0000
Subject: Fix handling of floating point imprecision in unnormalizing samples

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@3513 9d0c8265-081b-0410-96cb-a4ca84ce46f8
---
 editor/pambrighten.c | 28 ++++++++++++++--------------
 editor/pamcomp.c     |  3 ++-
 editor/pnmhisteq.c   |  2 +-
 editor/pnmnorm.c     |  4 ++--
 4 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/editor/pambrighten.c b/editor/pambrighten.c
index 462c5efe..51bd0d23 100644
--- a/editor/pambrighten.c
+++ b/editor/pambrighten.c
@@ -96,10 +96,10 @@ parseCommandLine(int                        argc,
 
 
 static void
-changeColorPix(tuple  const tupleval,
-               float  const valchange,
-               float  const satchange,
-               sample const maxval) {
+changeColorPix(tuple              const tupleval,
+               float              const valchange,
+               float              const satchange,
+               const struct pam * const pamP) {
 
     pixel oldRgb, newRgb;
     struct hsv oldHsv, newHsv;
@@ -107,7 +107,7 @@ changeColorPix(tuple  const tupleval,
     PPM_PUTR(oldRgb, tupleval[PAM_RED_PLANE]);
     PPM_PUTG(oldRgb, tupleval[PAM_GRN_PLANE]);
     PPM_PUTB(oldRgb, tupleval[PAM_BLU_PLANE]);
-    oldHsv = ppm_hsv_from_color(oldRgb, maxval);
+    oldHsv = ppm_hsv_from_color(oldRgb, pamP->maxval);
 
     newHsv.h = oldHsv.h;
 
@@ -115,7 +115,7 @@ changeColorPix(tuple  const tupleval,
 
     newHsv.v = MIN(1.0, MAX(0.0, oldHsv.v * valchange));
 
-    newRgb = ppm_color_from_hsv(newHsv, maxval);
+    newRgb = ppm_color_from_hsv(newHsv, pamP->maxval);
 
     tupleval[PAM_RED_PLANE] = PPM_GETR(newRgb);
     tupleval[PAM_GRN_PLANE] = PPM_GETG(newRgb);
@@ -125,14 +125,14 @@ changeColorPix(tuple  const tupleval,
 
 
 static void
-changeGrayPix(tuple  const tupleval,
-              float  const valchange,
-              sample const maxval) {
+changeGrayPix(tuple        const tupleval,
+              float        const valchange,
+              struct pam * const pamP) {
 
-    double const oldGray = (double) tupleval[0] / maxval;
-    double const newGray = MIN(1.0, MAX(0.0, oldGray * valchange));
+    samplen const oldGray = pnm_normalized_sample(pamP, tupleval[0]);
+    samplen const newGray = MIN(1.0, MAX(0.0, oldGray * valchange));
 
-    tupleval[0] = ROUNDU(newGray * maxval);
+    tupleval[0] = pnm_unnormalized_sample(pamP, newGray);
 }
 
 
@@ -211,12 +211,12 @@ pambrighten(struct CmdlineInfo const cmdline,
             case COLORTYPE_COLOR:
                 changeColorPix(tuplerow[col],
                                cmdline.valchange, cmdline.satchange,
-                               inpam.maxval);
+                               &inpam);
                 break;
             case COLORTYPE_GRAY:
                 changeGrayPix(tuplerow[col],
                               cmdline.valchange,
-                              inpam.maxval);
+                              &inpam);
                 break;
             case COLORTYPE_BW:
                 /* Nothing to change. */
diff --git a/editor/pamcomp.c b/editor/pamcomp.c
index 3e27731f..6e1e7f7d 100644
--- a/editor/pamcomp.c
+++ b/editor/pamcomp.c
@@ -532,7 +532,8 @@ composeComponents(sample           const compA,
             float const mix =
                 compALinear * distrib + compBLinearAdj * (1.0 - distrib)
                 * composedFactor;
-            sample const sampleValue = ROUNDU(pm_gamma709(mix) * maxval);
+            sample const sampleValue =
+                pnm_unnormalize(pm_gamma709(mix), maxval);
             retval = MIN(maxval, MAX(0, sampleValue));
         }
     }
diff --git a/editor/pnmhisteq.c b/editor/pnmhisteq.c
index 76fd6d2a..a339f73f 100644
--- a/editor/pnmhisteq.c
+++ b/editor/pnmhisteq.c
@@ -426,7 +426,7 @@ remapRgbValue(xel          const thisXel,
     struct hsv const hsv =
         ppm_hsv_from_color(thisXel, maxval);
     xelval const oldValue =
-        MIN(maxval, ROUNDU(hsv.v * maxval));
+        MIN(maxval, pnm_unnormalize(hsv.v, maxval));
     xelval const newValue =
         lumamap[oldValue];
 
diff --git a/editor/pnmnorm.c b/editor/pnmnorm.c
index 7762f049..2f9a6b20 100644
--- a/editor/pnmnorm.c
+++ b/editor/pnmnorm.c
@@ -714,7 +714,7 @@ computeQuadraticTransfer(xelval   const bvalue,
 
    Set this mapping in newBrightness[].
 -----------------------------------------------------------------------------*/
-    xelval const middle = ROUNDU(middleNorm * maxval);
+    xelval const middle = pnm_unnormalize(middleNorm, maxval);
 
     /* Computing this function is just the task of finding a parabola that
        passes through 3 given points:
@@ -924,7 +924,7 @@ reportTransferParm(bool   const quadratic,
     if (quadratic)
         pm_message("remapping %u..%u..%u to %u..%u..%u",
                    bvalue, midvalue, wvalue,
-                   0, ROUNDU(maxval*middle), maxval);
+                   0, pnm_unnormalize(middle, maxval), maxval);
     else
         pm_message("remapping %u..%u to %u..%u",
                    bvalue, wvalue, 0, maxval);
-- 
cgit 1.4.1