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-rw-r--r--src/3rdparty/libwebp/src/utils/filters.c266
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diff --git a/src/3rdparty/libwebp/src/utils/filters.c b/src/3rdparty/libwebp/src/utils/filters.c
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+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// 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>
+
+//------------------------------------------------------------------------------
+// Helpful macro.
+
+# define SANITY_CHECK(in, out) \
+ assert(in != NULL); \
+ assert(out != NULL); \
+ assert(width > 0); \
+ assert(height > 0); \
+ assert(stride >= width); \
+ assert(row >= 0 && num_rows > 0 && row + num_rows <= height); \
+ (void)height; // Silence unused warning.
+
+static WEBP_INLINE void PredictLine(const uint8_t* src, const uint8_t* pred,
+ uint8_t* dst, int length, int inverse) {
+ int i;
+ if (inverse) {
+ for (i = 0; i < length; ++i) dst[i] = src[i] + pred[i];
+ } else {
+ for (i = 0; i < length; ++i) dst[i] = src[i] - pred[i];
+ }
+}
+
+//------------------------------------------------------------------------------
+// Horizontal filter.
+
+static WEBP_INLINE void DoHorizontalFilter(const uint8_t* in,
+ int width, int height, int stride,
+ int row, int num_rows,
+ int inverse, uint8_t* out) {
+ const uint8_t* preds;
+ const size_t start_offset = row * stride;
+ const int last_row = row + num_rows;
+ SANITY_CHECK(in, out);
+ in += start_offset;
+ out += start_offset;
+ preds = inverse ? out : in;
+
+ if (row == 0) {
+ // Leftmost pixel is the same as input for topmost scanline.
+ out[0] = in[0];
+ PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+ row = 1;
+ preds += stride;
+ in += stride;
+ out += stride;
+ }
+
+ // Filter line-by-line.
+ while (row < last_row) {
+ // Leftmost pixel is predicted from above.
+ PredictLine(in, preds - stride, out, 1, inverse);
+ PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+ ++row;
+ preds += stride;
+ in += stride;
+ out += stride;
+ }
+}
+
+static void HorizontalFilter(const uint8_t* data, int width, int height,
+ int stride, uint8_t* filtered_data) {
+ DoHorizontalFilter(data, width, height, stride, 0, height, 0, filtered_data);
+}
+
+static void HorizontalUnfilter(int width, int height, int stride, int row,
+ int num_rows, uint8_t* data) {
+ DoHorizontalFilter(data, width, height, stride, row, num_rows, 1, data);
+}
+
+//------------------------------------------------------------------------------
+// Vertical filter.
+
+static WEBP_INLINE void DoVerticalFilter(const uint8_t* in,
+ int width, int height, int stride,
+ int row, int num_rows,
+ int inverse, uint8_t* out) {
+ const uint8_t* preds;
+ const size_t start_offset = row * stride;
+ const int last_row = row + num_rows;
+ SANITY_CHECK(in, out);
+ in += start_offset;
+ out += start_offset;
+ preds = inverse ? out : in;
+
+ if (row == 0) {
+ // Very first top-left pixel is copied.
+ out[0] = in[0];
+ // Rest of top scan-line is left-predicted.
+ PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+ row = 1;
+ in += stride;
+ out += stride;
+ } else {
+ // We are starting from in-between. Make sure 'preds' points to prev row.
+ preds -= stride;
+ }
+
+ // Filter line-by-line.
+ while (row < last_row) {
+ PredictLine(in, preds, out, width, inverse);
+ ++row;
+ preds += stride;
+ in += stride;
+ out += stride;
+ }
+}
+
+static void VerticalFilter(const uint8_t* data, int width, int height,
+ int stride, uint8_t* filtered_data) {
+ DoVerticalFilter(data, width, height, stride, 0, height, 0, filtered_data);
+}
+
+static void VerticalUnfilter(int width, int height, int stride, int row,
+ int num_rows, uint8_t* data) {
+ DoVerticalFilter(data, width, height, stride, row, num_rows, 1, data);
+}
+
+//------------------------------------------------------------------------------
+// Gradient filter.
+
+static WEBP_INLINE int GradientPredictor(uint8_t a, uint8_t b, uint8_t c) {
+ const int g = a + b - c;
+ return ((g & ~0xff) == 0) ? g : (g < 0) ? 0 : 255; // clip to 8bit
+}
+
+static WEBP_INLINE void DoGradientFilter(const uint8_t* in,
+ int width, int height, int stride,
+ int row, int num_rows,
+ int inverse, uint8_t* out) {
+ const uint8_t* preds;
+ const size_t start_offset = row * stride;
+ const int last_row = row + num_rows;
+ SANITY_CHECK(in, out);
+ in += start_offset;
+ out += start_offset;
+ preds = inverse ? out : in;
+
+ // left prediction for top scan-line
+ if (row == 0) {
+ out[0] = in[0];
+ PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+ row = 1;
+ preds += stride;
+ in += stride;
+ out += stride;
+ }
+
+ // Filter line-by-line.
+ while (row < last_row) {
+ int w;
+ // leftmost pixel: predict from above.
+ PredictLine(in, preds - stride, out, 1, inverse);
+ for (w = 1; w < width; ++w) {
+ const int pred = GradientPredictor(preds[w - 1],
+ preds[w - stride],
+ preds[w - stride - 1]);
+ out[w] = in[w] + (inverse ? pred : -pred);
+ }
+ ++row;
+ preds += stride;
+ in += stride;
+ out += stride;
+ }
+}
+
+static void GradientFilter(const uint8_t* data, int width, int height,
+ int stride, uint8_t* filtered_data) {
+ DoGradientFilter(data, width, height, stride, 0, height, 0, filtered_data);
+}
+
+static void GradientUnfilter(int width, int height, int stride, int row,
+ int num_rows, uint8_t* data) {
+ DoGradientFilter(data, width, height, stride, row, num_rows, 1, data);
+}
+
+#undef SANITY_CHECK
+
+// -----------------------------------------------------------------------------
+// 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]);
+ const int diff3 = SDIFF(p[i], grad_pred);
+ bins[WEBP_FILTER_NONE][diff0] = 1;
+ bins[WEBP_FILTER_HORIZONTAL][diff1] = 1;
+ bins[WEBP_FILTER_VERTICAL][diff2] = 1;
+ bins[WEBP_FILTER_GRADIENT][diff3] = 1;
+ mean = (3 * mean + p[i] + 2) >> 2;
+ }
+ }
+ {
+ int filter;
+ WEBP_FILTER_TYPE best_filter = WEBP_FILTER_NONE;
+ int best_score = 0x7fffffff;
+ for (filter = WEBP_FILTER_NONE; filter < WEBP_FILTER_LAST; ++filter) {
+ int score = 0;
+ for (i = 0; i < SMAX; ++i) {
+ if (bins[filter][i] > 0) {
+ score += i;
+ }
+ }
+ if (score < best_score) {
+ best_score = score;
+ best_filter = (WEBP_FILTER_TYPE)filter;
+ }
+ }
+ return best_filter;
+ }
+}
+
+#undef SMAX
+#undef SDIFF
+
+//------------------------------------------------------------------------------
+
+const WebPFilterFunc WebPFilters[WEBP_FILTER_LAST] = {
+ NULL, // WEBP_FILTER_NONE
+ HorizontalFilter, // WEBP_FILTER_HORIZONTAL
+ VerticalFilter, // WEBP_FILTER_VERTICAL
+ GradientFilter // WEBP_FILTER_GRADIENT
+};
+
+const WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST] = {
+ NULL, // WEBP_FILTER_NONE
+ HorizontalUnfilter, // WEBP_FILTER_HORIZONTAL
+ VerticalUnfilter, // WEBP_FILTER_VERTICAL
+ GradientUnfilter // WEBP_FILTER_GRADIENT
+};
+
+//------------------------------------------------------------------------------
+
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