From 5df5c1c13ca93875be9e5092309693cd029fa7c7 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Fri, 13 Oct 2017 13:52:31 +0200
Subject: [PATCH] Correct rendering of cat images.

---
 src/PNGDumper.cpp | 15 ++++++++-------
 src/utils.hpp     |  8 ++++----
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/PNGDumper.cpp b/src/PNGDumper.cpp
index 92fb330..144df8e 100644
--- a/src/PNGDumper.cpp
+++ b/src/PNGDumper.cpp
@@ -47,17 +47,18 @@ void PNGDumper::dump(const LayerData &layerData)
 void PNGDumper::dumpImageSeries(const LayerData &layer)
 {
     const auto& shape = layer.shape();
-    const auto imagePixels = shape[2] * shape[3];
+    const auto images = shape[0], channels = shape[1], height = shape[2], width = shape[3];
+    const auto imagePixels = width * height;
 
     // Buffer for storing the current image data.
     vector<DType> buffer(imagePixels);
 
     auto data = layer.data();
 
-    png::image<png::gray_pixel> image(shape[2], shape[3]);
+    png::image<png::gray_pixel> image(width, height);
 
-    for (int i = 0; i < shape[0]; ++i) {
-        for (int j = 0; j < shape[1]; ++j) {
+    for (int i = 0; i < images; ++i) {
+        for (int j = 0; j < channels; ++j) {
             memcpy(buffer.data(), data, imagePixels * sizeof(DType));
 
             // advance the buffer;
@@ -65,9 +66,9 @@ void PNGDumper::dumpImageSeries(const LayerData &layer)
 
             clamp(buffer.begin(), buffer.end(), 0.0, 255.0);
 
-            for (int y = 0; y < shape[2]; ++y) {
-                for (int x = 0; x < shape[3]; ++x) {
-                    image[x][y] = png::gray_pixel((int) buffer[x + y * shape[3]]);
+            for (int y = 0; y < height; ++y) {
+                for (int x = 0; x < width; ++x) {
+                    image[y][x] = png::gray_pixel((int) buffer[x + y * width]);
                 }
             }
 
diff --git a/src/utils.hpp b/src/utils.hpp
index 97549c5..5ae628b 100644
--- a/src/utils.hpp
+++ b/src/utils.hpp
@@ -91,11 +91,11 @@ namespace fmri
                typename std::iterator_traits<It>::value_type minimum,
                typename std::iterator_traits<It>::value_type maximum)
     {
-        const auto extremes = std::minmax(begin, end);
-        const auto diff = *extremes.second - *extremes.first;
+        const auto[minElem, maxElem] = std::minmax(begin, end);
+        const auto diff = *maxElem - *minElem;
 
-        const auto offset = minimum - *extremes.first;
-        const auto scaling = diff / (maximum - minimum);
+        const auto offset = minimum - *minElem;
+        const auto scaling = (maximum - minimum) / diff;
 
         std::for_each(begin, end, [offset, scaling] (typename std::iterator_traits<It>::reference v) { v = (v + offset) * scaling;});
     }