libwebp-0.3.1

third_party/libwebp/utils/filters.c

 // Copyright 2011 Google Inc. All Rights Reserved.
 //
-// This code is licensed under the same terms as WebM:
-//  Software License Agreement:  http://www.webmproject.org/license/software/
-//  Additional IP Rights Grant:  http://www.webmproject.org/license/additional/
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // Spatial prediction using various filters
 //
 // Author: Urvang (urvang@google.com)
 
 #include "./filters.h"
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 131 matching lines @@
   DoGradientFilter(data, width, height, stride, 0, filtered_data);
 }
 
 static void GradientUnfilter(int width, int height, int stride, uint8_t* data) {
   DoGradientFilter(data, width, height, stride, 1, data);
 }
 
 #undef SANITY_CHECK
 
 // -----------------------------------------------------------------------------
-// Quick estimate of a potentially interesting filter mode to try, in addition
-// to the default NONE.
+// Quick estimate of a potentially interesting filter mode to try.
 
 #define SMAX 16
 #define SDIFF(a, b) (abs((a) - (b)) >> 4)   // Scoring diff, in [0..SMAX)
 
 WEBP_FILTER_TYPE EstimateBestFilter(const uint8_t* data,
                                     int width, int height, int stride) {
   int i, j;
   int bins[WEBP_FILTER_LAST][SMAX];
   memset(bins, 0, sizeof(bins));
+
   // We only sample every other pixels. That's enough.
   for (j = 2; j < height - 1; j += 2) {
     const uint8_t* const p = data + j * stride;
     int mean = p[0];
     for (i = 2; i < width - 1; i += 2) {
       const int diff0 = SDIFF(p[i], mean);
       const int diff1 = SDIFF(p[i], p[i - 1]);
       const int diff2 = SDIFF(p[i], p[i - width]);
       const int grad_pred =
           GradientPredictor(p[i - 1], p[i - width], p[i - width - 1]);
@@ skipping 41 matching lines @@
   HorizontalUnfilter,  // WEBP_FILTER_HORIZONTAL
   VerticalUnfilter,    // WEBP_FILTER_VERTICAL
   GradientUnfilter     // WEBP_FILTER_GRADIENT
 };
 
 //------------------------------------------------------------------------------
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }    // extern "C"
 #endif