Dump intermediate results to PNG images.

src/PNGDumper.cpp

@@ -0,0 +1,89 @@
+#include <cstring>
+
+#include <glog/logging.h>
+#include <sys/stat.h>
+#include <png++/png.hpp>
+
+#include "PNGDumper.hpp"
+
+using namespace fmri;
+using namespace std;
+
+static void ensureDir(const string& dir)
+{
+    struct stat s;
+    if (stat(dir.c_str(), &s) == 0) {
+        CHECK(S_ISDIR(s.st_mode)) << dir << " already exists and is not a directory." << endl;
+        return;
+    }
+
+    switch (errno) {
+        case ENOENT:
+            PCHECK(mkdir(dir.c_str(), 0777) == 0) << "Couldn't create directory";
+            return;
+
+        default:
+            perror("Unusable dump dir");
+            break;
+    }
+}
+
+PNGDumper::PNGDumper(string_view baseDir) :
+        baseDir_(baseDir)
+{
+    ensureDir(baseDir_);
+}
+
+void PNGDumper::dump(const LayerData &layerData)
+{
+    if (layerData.shape().size() == 4) {
+        // We have a series of images.
+        dumpImageSeries(layerData);
+    } else {
+        LOG(INFO) << "Unable to dump this type of layer to png.";
+    }
+}
+
+void PNGDumper::dumpImageSeries(const LayerData &layer)
+{
+    const auto& shape = layer.shape();
+    const auto imagePixels = shape[2] * shape[3];
+
+    // Buffer for storing the current image data.
+    vector<DType> buffer(imagePixels);
+
+    auto data = layer.data();
+
+    for (int i = 0; i < shape[0]; ++i) {
+        for (int j = 0; j < shape[1]; ++j) {
+            memcpy(buffer.data(), data, imagePixels * sizeof(DType));
+
+            // advance the buffer;
+            data += imagePixels;
+
+            clamp(buffer.begin(), buffer.end(), 0.0, 255.0);
+
+            png::image<png::gray_pixel> image(shape[2], shape[3]);
+
+            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]]);
+                }
+            }
+
+            image.write(getFilename(layer.name(), i, j));
+        }
+    }
+}
+
+string PNGDumper::getFilename(const string &layerName, int i, int j)
+{
+    stringstream nameBuilder;
+
+    nameBuilder << baseDir_
+                << "/" << layerName
+                << "-" << i
+                << "-" << j << ".png";
+
+    return nameBuilder.str();
+}