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Diffstat (limited to 'media/libwebp/enc/picture_tools_enc.c')
-rw-r--r--media/libwebp/enc/picture_tools_enc.c273
1 files changed, 273 insertions, 0 deletions
diff --git a/media/libwebp/enc/picture_tools_enc.c b/media/libwebp/enc/picture_tools_enc.c
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index 0000000000..02d48c5223
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+++ b/media/libwebp/enc/picture_tools_enc.c
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+// Copyright 2014 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.
+// -----------------------------------------------------------------------------
+//
+// WebPPicture tools: alpha handling, etc.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <assert.h>
+
+#include "../enc/vp8i_enc.h"
+#include "../dsp/yuv.h"
+
+//------------------------------------------------------------------------------
+// Helper: clean up fully transparent area to help compressibility.
+
+#define SIZE 8
+#define SIZE2 (SIZE / 2)
+static int IsTransparentARGBArea(const uint32_t* ptr, int stride, int size) {
+ int y, x;
+ for (y = 0; y < size; ++y) {
+ for (x = 0; x < size; ++x) {
+ if (ptr[x] & 0xff000000u) {
+ return 0;
+ }
+ }
+ ptr += stride;
+ }
+ return 1;
+}
+
+static void Flatten(uint8_t* ptr, int v, int stride, int size) {
+ int y;
+ for (y = 0; y < size; ++y) {
+ memset(ptr, v, size);
+ ptr += stride;
+ }
+}
+
+static void FlattenARGB(uint32_t* ptr, uint32_t v, int stride, int size) {
+ int x, y;
+ for (y = 0; y < size; ++y) {
+ for (x = 0; x < size; ++x) ptr[x] = v;
+ ptr += stride;
+ }
+}
+
+// Smoothen the luma components of transparent pixels. Return true if the whole
+// block is transparent.
+static int SmoothenBlock(const uint8_t* a_ptr, int a_stride, uint8_t* y_ptr,
+ int y_stride, int width, int height) {
+ int sum = 0, count = 0;
+ int x, y;
+ const uint8_t* alpha_ptr = a_ptr;
+ uint8_t* luma_ptr = y_ptr;
+ for (y = 0; y < height; ++y) {
+ for (x = 0; x < width; ++x) {
+ if (alpha_ptr[x] != 0) {
+ ++count;
+ sum += luma_ptr[x];
+ }
+ }
+ alpha_ptr += a_stride;
+ luma_ptr += y_stride;
+ }
+ if (count > 0 && count < width * height) {
+ const uint8_t avg_u8 = (uint8_t)(sum / count);
+ alpha_ptr = a_ptr;
+ luma_ptr = y_ptr;
+ for (y = 0; y < height; ++y) {
+ for (x = 0; x < width; ++x) {
+ if (alpha_ptr[x] == 0) luma_ptr[x] = avg_u8;
+ }
+ alpha_ptr += a_stride;
+ luma_ptr += y_stride;
+ }
+ }
+ return (count == 0);
+}
+
+void WebPReplaceTransparentPixels(WebPPicture* const pic, uint32_t color) {
+ if (pic != NULL && pic->use_argb) {
+ int y = pic->height;
+ uint32_t* argb = pic->argb;
+ color &= 0xffffffu; // force alpha=0
+ WebPInitAlphaProcessing();
+ while (y-- > 0) {
+ WebPAlphaReplace(argb, pic->width, color);
+ argb += pic->argb_stride;
+ }
+ }
+}
+
+void WebPCleanupTransparentArea(WebPPicture* pic) {
+ int x, y, w, h;
+ if (pic == NULL) return;
+ w = pic->width / SIZE;
+ h = pic->height / SIZE;
+
+ // note: we ignore the left-overs on right/bottom, except for SmoothenBlock().
+ if (pic->use_argb) {
+ uint32_t argb_value = 0;
+ for (y = 0; y < h; ++y) {
+ int need_reset = 1;
+ for (x = 0; x < w; ++x) {
+ const int off = (y * pic->argb_stride + x) * SIZE;
+ if (IsTransparentARGBArea(pic->argb + off, pic->argb_stride, SIZE)) {
+ if (need_reset) {
+ argb_value = pic->argb[off];
+ need_reset = 0;
+ }
+ FlattenARGB(pic->argb + off, argb_value, pic->argb_stride, SIZE);
+ } else {
+ need_reset = 1;
+ }
+ }
+ }
+ } else {
+ const int width = pic->width;
+ const int height = pic->height;
+ const int y_stride = pic->y_stride;
+ const int uv_stride = pic->uv_stride;
+ const int a_stride = pic->a_stride;
+ uint8_t* y_ptr = pic->y;
+ uint8_t* u_ptr = pic->u;
+ uint8_t* v_ptr = pic->v;
+ const uint8_t* a_ptr = pic->a;
+ int values[3] = { 0 };
+ if (a_ptr == NULL || y_ptr == NULL || u_ptr == NULL || v_ptr == NULL) {
+ return;
+ }
+ for (y = 0; y + SIZE <= height; y += SIZE) {
+ int need_reset = 1;
+ for (x = 0; x + SIZE <= width; x += SIZE) {
+ if (SmoothenBlock(a_ptr + x, a_stride, y_ptr + x, y_stride,
+ SIZE, SIZE)) {
+ if (need_reset) {
+ values[0] = y_ptr[x];
+ values[1] = u_ptr[x >> 1];
+ values[2] = v_ptr[x >> 1];
+ need_reset = 0;
+ }
+ Flatten(y_ptr + x, values[0], y_stride, SIZE);
+ Flatten(u_ptr + (x >> 1), values[1], uv_stride, SIZE2);
+ Flatten(v_ptr + (x >> 1), values[2], uv_stride, SIZE2);
+ } else {
+ need_reset = 1;
+ }
+ }
+ if (x < width) {
+ SmoothenBlock(a_ptr + x, a_stride, y_ptr + x, y_stride,
+ width - x, SIZE);
+ }
+ a_ptr += SIZE * a_stride;
+ y_ptr += SIZE * y_stride;
+ u_ptr += SIZE2 * uv_stride;
+ v_ptr += SIZE2 * uv_stride;
+ }
+ if (y < height) {
+ const int sub_height = height - y;
+ for (x = 0; x + SIZE <= width; x += SIZE) {
+ SmoothenBlock(a_ptr + x, a_stride, y_ptr + x, y_stride,
+ SIZE, sub_height);
+ }
+ if (x < width) {
+ SmoothenBlock(a_ptr + x, a_stride, y_ptr + x, y_stride,
+ width - x, sub_height);
+ }
+ }
+ }
+}
+
+#undef SIZE
+#undef SIZE2
+
+//------------------------------------------------------------------------------
+// Blend color and remove transparency info
+
+#define BLEND(V0, V1, ALPHA) \
+ ((((V0) * (255 - (ALPHA)) + (V1) * (ALPHA)) * 0x101 + 256) >> 16)
+#define BLEND_10BIT(V0, V1, ALPHA) \
+ ((((V0) * (1020 - (ALPHA)) + (V1) * (ALPHA)) * 0x101 + 1024) >> 18)
+
+static WEBP_INLINE uint32_t MakeARGB32(int r, int g, int b) {
+ return (0xff000000u | (r << 16) | (g << 8) | b);
+}
+
+void WebPBlendAlpha(WebPPicture* pic, uint32_t background_rgb) {
+ const int red = (background_rgb >> 16) & 0xff;
+ const int green = (background_rgb >> 8) & 0xff;
+ const int blue = (background_rgb >> 0) & 0xff;
+ int x, y;
+ if (pic == NULL) return;
+ if (!pic->use_argb) {
+ const int uv_width = (pic->width >> 1); // omit last pixel during u/v loop
+ const int Y0 = VP8RGBToY(red, green, blue, YUV_HALF);
+ // VP8RGBToU/V expects the u/v values summed over four pixels
+ const int U0 = VP8RGBToU(4 * red, 4 * green, 4 * blue, 4 * YUV_HALF);
+ const int V0 = VP8RGBToV(4 * red, 4 * green, 4 * blue, 4 * YUV_HALF);
+ const int has_alpha = pic->colorspace & WEBP_CSP_ALPHA_BIT;
+ uint8_t* y_ptr = pic->y;
+ uint8_t* u_ptr = pic->u;
+ uint8_t* v_ptr = pic->v;
+ uint8_t* a_ptr = pic->a;
+ if (!has_alpha || a_ptr == NULL) return; // nothing to do
+ for (y = 0; y < pic->height; ++y) {
+ // Luma blending
+ for (x = 0; x < pic->width; ++x) {
+ const uint8_t alpha = a_ptr[x];
+ if (alpha < 0xff) {
+ y_ptr[x] = BLEND(Y0, y_ptr[x], alpha);
+ }
+ }
+ // Chroma blending every even line
+ if ((y & 1) == 0) {
+ uint8_t* const a_ptr2 =
+ (y + 1 == pic->height) ? a_ptr : a_ptr + pic->a_stride;
+ for (x = 0; x < uv_width; ++x) {
+ // Average four alpha values into a single blending weight.
+ // TODO(skal): might lead to visible contouring. Can we do better?
+ const uint32_t alpha =
+ a_ptr[2 * x + 0] + a_ptr[2 * x + 1] +
+ a_ptr2[2 * x + 0] + a_ptr2[2 * x + 1];
+ u_ptr[x] = BLEND_10BIT(U0, u_ptr[x], alpha);
+ v_ptr[x] = BLEND_10BIT(V0, v_ptr[x], alpha);
+ }
+ if (pic->width & 1) { // rightmost pixel
+ const uint32_t alpha = 2 * (a_ptr[2 * x + 0] + a_ptr2[2 * x + 0]);
+ u_ptr[x] = BLEND_10BIT(U0, u_ptr[x], alpha);
+ v_ptr[x] = BLEND_10BIT(V0, v_ptr[x], alpha);
+ }
+ } else {
+ u_ptr += pic->uv_stride;
+ v_ptr += pic->uv_stride;
+ }
+ memset(a_ptr, 0xff, pic->width); // reset alpha value to opaque
+ a_ptr += pic->a_stride;
+ y_ptr += pic->y_stride;
+ }
+ } else {
+ uint32_t* argb = pic->argb;
+ const uint32_t background = MakeARGB32(red, green, blue);
+ for (y = 0; y < pic->height; ++y) {
+ for (x = 0; x < pic->width; ++x) {
+ const int alpha = (argb[x] >> 24) & 0xff;
+ if (alpha != 0xff) {
+ if (alpha > 0) {
+ int r = (argb[x] >> 16) & 0xff;
+ int g = (argb[x] >> 8) & 0xff;
+ int b = (argb[x] >> 0) & 0xff;
+ r = BLEND(red, r, alpha);
+ g = BLEND(green, g, alpha);
+ b = BLEND(blue, b, alpha);
+ argb[x] = MakeARGB32(r, g, b);
+ } else {
+ argb[x] = background;
+ }
+ }
+ }
+ argb += pic->argb_stride;
+ }
+ }
+}
+
+#undef BLEND
+#undef BLEND_10BIT
+
+//------------------------------------------------------------------------------
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