diff options
Diffstat (limited to 'media/libwebp/src/enc/picture_tools_enc.c')
| -rw-r--r-- | media/libwebp/src/enc/picture_tools_enc.c | 274 |
1 files changed, 274 insertions, 0 deletions
diff --git a/media/libwebp/src/enc/picture_tools_enc.c b/media/libwebp/src/enc/picture_tools_enc.c new file mode 100644 index 0000000000..147cc18608 --- /dev/null +++ b/media/libwebp/src/enc/picture_tools_enc.c @@ -0,0 +1,274 @@ +// 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 "src/enc/vp8i_enc.h" +#include "src/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* picture, 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 (picture == NULL) return; + if (!picture->use_argb) { + // omit last pixel during u/v loop + const int uv_width = (picture->width >> 1); + 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 = picture->colorspace & WEBP_CSP_ALPHA_BIT; + uint8_t* y_ptr = picture->y; + uint8_t* u_ptr = picture->u; + uint8_t* v_ptr = picture->v; + uint8_t* a_ptr = picture->a; + if (!has_alpha || a_ptr == NULL) return; // nothing to do + for (y = 0; y < picture->height; ++y) { + // Luma blending + for (x = 0; x < picture->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 == picture->height) ? a_ptr : a_ptr + picture->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 (picture->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 += picture->uv_stride; + v_ptr += picture->uv_stride; + } + memset(a_ptr, 0xff, picture->width); // reset alpha value to opaque + a_ptr += picture->a_stride; + y_ptr += picture->y_stride; + } + } else { + uint32_t* argb = picture->argb; + const uint32_t background = MakeARGB32(red, green, blue); + for (y = 0; y < picture->height; ++y) { + for (x = 0; x < picture->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 += picture->argb_stride; + } + } +} + +#undef BLEND +#undef BLEND_10BIT + +//------------------------------------------------------------------------------ |