1 files changed, 105 insertions, 0 deletions
diff --git a/src/process/im_histogram.cpp b/src/process/im_histogram.cpp
new file mode 100644
index 0000000..e6796fe
--- /dev/null
+++ b/src/process/im_histogram.cpp
@@ -0,0 +1,105 @@
+/** \file
+ * \brief Histogram Based Operations
+ *
+ * See Copyright Notice in im_lib.h
+ * $Id: im_histogram.cpp,v 1.1 2008/10/17 06:16:33 scuri Exp $
+ */
+
+
+#include <im.h>
+#include <im_util.h>
+#include <im_math.h>
+
+#include "im_process_pon.h"
+#include "im_process_ana.h"
+
+#include <stdlib.h>
+#include <memory.h>
+
+static void iExpandHistogram(const imImage* src_image, imImage* dst_image, int low_level, int high_level)
+{
+  int i, value;
+
+  imbyte re_map[256];
+  memset(re_map, 0, 256);
+
+  int range = high_level-low_level+1;
+  float factor = 256.0f / (float)range;
+
+  for (i = 0; i < 256; i++)
+  {             
+    if (i < low_level)
+      re_map[i] = 0;
+    else if (i > high_level)
+      re_map[i] = 255;
+    else
+    {
+      value = imResample(i - low_level, factor);
+      re_map[i] = (imbyte)IM_BYTECROP(value);
+    }
+  }
+
+  imbyte* dst_map = (imbyte*)dst_image->data[0];
+  imbyte* src_map = (imbyte*)src_image->data[0];
+  int total_count = src_image->count*src_image->depth;
+  for (i = 0; i < total_count; i++)
+    dst_map[i] = re_map[src_map[i]];
+}
+
+void imProcessExpandHistogram(const imImage* src_image, imImage* dst_image, float percent)
+{
+  unsigned long histo[256];
+  imCalcGrayHistogram(src_image, histo, 0);
+
+  unsigned long acum, cut = (unsigned long)((src_image->count * percent) / 100.0f);
+  int low_level, high_level;
+
+  acum = 0;
+  for (low_level = 0; low_level < 256; low_level++)
+  {  
+    acum += histo[low_level];
+    if (acum > cut)
+      break;
+  }
+
+  acum = 0;
+  for (high_level = 255; high_level > 0; high_level--)
+  {  
+    acum += histo[high_level];
+    if (acum > cut)
+      break;
+  }
+
+  if (low_level >= high_level)
+  {
+    low_level = 0;
+    high_level = 255;
+  }
+
+  iExpandHistogram(src_image, dst_image, low_level, high_level);
+}
+
+void imProcessEqualizeHistogram(const imImage* src_image, imImage* dst_image)
+{
+  int i, value;
+
+  imbyte re_map[256];
+  memset(re_map, 0, 256);
+
+  unsigned long histo[256];
+  imCalcGrayHistogram(src_image, histo, 1);
+
+  float factor = 256.0f / (float)src_image->count;
+
+  for (i = 0; i < 256; i++)
+  {             
+    value = imResample(histo[i], factor);
+    re_map[i] = (imbyte)IM_BYTECROP(value);
+  }
+
+  imbyte* dst_map = (imbyte*)dst_image->data[0];
+  imbyte* src_map = (imbyte*)src_image->data[0];
+  int total_count = src_image->count*src_image->depth;
+  for (i = 0; i < total_count; i++)
+    dst_map[i] = re_map[src_map[i]];
+}