From ade1f77fe487964c26e0a7e171413596ee9abcbf Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <pavel@cs.unc.edu>
Date: Thu, 19 Feb 2015 23:17:07 -0800
Subject: [PATCH] Fix bugs and get tests passing

---
 Base/src/Image.cpp      | 11 +++++++----
 Base/test/TestImage.cpp | 30 ++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/Base/src/Image.cpp b/Base/src/Image.cpp
index bab3457..86e1db5 100644
--- a/Base/src/Image.cpp
+++ b/Base/src/Image.cpp
@@ -672,17 +672,20 @@ static void IDCT(Image<IPixel> *img) {
         for (unsigned int u = 0; u < img->GetWidth(); ++u) {
           float fu = static_cast<float>(u);
           float fv = static_cast<float>(v);
-          new_img(x, y) += (*img)(u, v)
+
+          float idct = (*img)(u, v)
             * cos(((2*fx + 1) * fu * M_PI) / (2 * N))
             * cos(((2*fy + 1) * fv * M_PI) / (2 * M));
 
           if (u == 0 && v == 0) {
-            new_img(x, y) /= N;
+            idct /= N;
           } else if (u == 0 || v == 0) {
-            new_img(x, y) /= sqrt(2) / N;
+            idct *= sqrt(2) / N;
           } else {
-            new_img(x, y) *= 2 / N;
+            idct *= 2 / N;
           }
+
+          new_img(x, y) += FasTC::IPixel(idct);
         }
       }
     }
diff --git a/Base/test/TestImage.cpp b/Base/test/TestImage.cpp
index 70512eb..419bca7 100644
--- a/Base/test/TestImage.cpp
+++ b/Base/test/TestImage.cpp
@@ -213,6 +213,33 @@ TEST(Image, SplitImage) {
 }
 
 TEST(Image, DCT) {
+  const uint32 w = 32;
+  const uint32 h = 32;
+
+  FasTC::Image<FasTC::IPixel> img(w, h);
+  for (uint32 j = 0; j < h; ++j) {
+    for (uint32 i = 0; i < w; ++i) {
+      img(i, j) = static_cast<FasTC::IPixel>(1);
+    }
+  }
+
+  // Make sure that taking the DCT and inverse DCT returns
+  // the same image...
+  FasTC::DiscreteCosineXForm(&img, 8);
+
+  // First make sure they're different
+  for (uint32 j = 0; j < h; ++j) {
+    for (uint32 i = 0; i < w; ++i) {
+      if ( (i % 8) == 0 && (j % 8) == 0 ) {
+        EXPECT_NEAR(img(i, j), 8.0f, 1e-5);
+      } else {
+        EXPECT_NEAR(img(i, j), 0.0f, 1e-5);
+      }
+    }
+  }  
+}
+
+TEST(Image, IDCT) {
 
   const uint32 w = 32;
   const uint32 h = 32;
@@ -221,7 +248,6 @@ TEST(Image, DCT) {
   for (uint32 j = 0; j < h; ++j) {
     for (uint32 i = 0; i < w; ++i) {
       img(i, j) = static_cast<FasTC::IPixel>(i + j);
-//      img(i, j) = static_cast<FasTC::IPixel>(1);
     }
   }
 
@@ -242,7 +268,7 @@ TEST(Image, DCT) {
 
   for (uint32 j = 0; j < h; ++j) {
     for (uint32 i = 0; i < w; ++i) {
-      EXPECT_NEAR(img(i, j), orig(i, j), 1e-5);
+      EXPECT_NEAR(img(i, j), orig(i, j), 1e-4);
     }
   }
 }