From 841a1b0c72a192388f88d0f4c63b010ddf1ab9e5 Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <pavel@cs.unc.edu>
Date: Sun, 20 Dec 2015 17:42:22 -0500
Subject: [PATCH] Add multiplier to make the differences more noticable

---
 Base/include/FasTC/Image.h |  2 +-
 Base/src/Image.cpp         |  3 ++-
 CLTool/src/compare.cpp     | 13 +++++++++++--
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Base/include/FasTC/Image.h b/Base/include/FasTC/Image.h
index 2f1997b..4723370 100644
--- a/Base/include/FasTC/Image.h
+++ b/Base/include/FasTC/Image.h
@@ -97,7 +97,7 @@ namespace FasTC {
     double ComputePSNR(Image<PixelType> *other);
     double ComputeSSIM(Image<PixelType> *other);
 
-    Image<PixelType> Diff(Image<PixelType> *other);
+    Image<PixelType> Diff(Image<PixelType> *other, float mult);
 
     double ComputeEntropy();
     double ComputeMeanLocalEntropy();
diff --git a/Base/src/Image.cpp b/Base/src/Image.cpp
index 405cb99..d0c3f89 100644
--- a/Base/src/Image.cpp
+++ b/Base/src/Image.cpp
@@ -199,7 +199,7 @@ const PixelType & Image<PixelType>::operator()(uint32 i, uint32 j) const {
 }
 
 template<typename PixelType>
-Image<PixelType> Image<PixelType>::Diff(Image<PixelType> *other) {
+Image<PixelType> Image<PixelType>::Diff(Image<PixelType> *other, float mult) {
   if (!other) {
     std::cerr << "Image::Diff - ERROR: other == null" << std::endl;
     assert(false);
@@ -219,6 +219,7 @@ Image<PixelType> Image<PixelType>::Diff(Image<PixelType> *other) {
   for (int j = 0; j < GetHeight(); ++j) {
     for (int i = 0; i < GetWidth(); ++i) {
       result(i, j) = PixelAbs((*this)(i, j) - (*other)(i, j));
+      result(i, j) *= mult;
       result(i, j).MakeOpaque();
     }
   }
diff --git a/CLTool/src/compare.cpp b/CLTool/src/compare.cpp
index 039cf7a..49d5fed 100644
--- a/CLTool/src/compare.cpp
+++ b/CLTool/src/compare.cpp
@@ -80,15 +80,24 @@ void gen_random(char *s, const int len) {
 }
 
 int main(int argc, char **argv) {
-  if(argc != 3 && argc != 4) {
+  if(argc < 3 || argc > 5) {
     PrintUsageAndExit();
   }
 
   bool diff_images = false;
+  float diff_multiplier = 1.0;
   int arg = 1;
   if (strncmp(argv[arg], "-d", 2) == 0) {
     diff_images = true;
     arg++;
+
+    if (argc == 5) {
+      diff_multiplier = static_cast<float>(atoi(argv[arg]));
+      if (diff_multiplier < 0) {
+        PrintUsageAndExit();
+      }
+      arg++;
+    }
   }
 
   ImageFile img1f (argv[arg]);
@@ -109,7 +118,7 @@ int main(int argc, char **argv) {
   FasTC::Image<> &img2 = *img2f.GetImage();
 
   if (diff_images) {
-    FasTC::Image<> diff = img1.Diff(&img2);
+    FasTC::Image<> diff = img1.Diff(&img2, diff_multiplier);
 
     char fname_buf [5 + 16 + 4]; // "diff-" + hash + ".png"
     strncat(fname_buf, "diff-", 5);