| // 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 "./vp8enci.h" |
| #include "../dsp/yuv.h" |
| |
| static WEBP_INLINE uint32_t MakeARGB32(int r, int g, int b) { |
| return (0xff000000u | (r << 16) | (g << 8) | b); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Helper: clean up fully transparent area to help compressibility. |
| |
| #define SIZE 8 |
| #define SIZE2 (SIZE / 2) |
| static int is_transparent_area(const uint8_t* ptr, int stride, int size) { |
| int y, x; |
| for (y = 0; y < size; ++y) { |
| for (x = 0; x < size; ++x) { |
| if (ptr[x]) { |
| return 0; |
| } |
| } |
| ptr += stride; |
| } |
| return 1; |
| } |
| |
| static int is_transparent_argb_area(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 flatten_argb(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; |
| } |
| } |
| |
| 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 |
| 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 (is_transparent_argb_area(pic->argb + off, pic->argb_stride, SIZE)) { |
| if (need_reset) { |
| argb_value = pic->argb[off]; |
| need_reset = 0; |
| } |
| flatten_argb(pic->argb + off, argb_value, pic->argb_stride, SIZE); |
| } else { |
| need_reset = 1; |
| } |
| } |
| } |
| } else { |
| const uint8_t* const a_ptr = pic->a; |
| int values[3] = { 0 }; |
| if (a_ptr == NULL) return; // nothing to do |
| for (y = 0; y < h; ++y) { |
| int need_reset = 1; |
| for (x = 0; x < w; ++x) { |
| const int off_a = (y * pic->a_stride + x) * SIZE; |
| const int off_y = (y * pic->y_stride + x) * SIZE; |
| const int off_uv = (y * pic->uv_stride + x) * SIZE2; |
| if (is_transparent_area(a_ptr + off_a, pic->a_stride, SIZE)) { |
| if (need_reset) { |
| values[0] = pic->y[off_y]; |
| values[1] = pic->u[off_uv]; |
| values[2] = pic->v[off_uv]; |
| need_reset = 0; |
| } |
| flatten(pic->y + off_y, values[0], pic->y_stride, SIZE); |
| flatten(pic->u + off_uv, values[1], pic->uv_stride, SIZE2); |
| flatten(pic->v + off_uv, values[2], pic->uv_stride, SIZE2); |
| } else { |
| need_reset = 1; |
| } |
| } |
| } |
| } |
| } |
| |
| #undef SIZE |
| #undef SIZE2 |
| |
| //------------------------------------------------------------------------------ |
| // Blend color and remove transparency info |
| |
| #define BLEND(V0, V1, ALPHA) \ |
| ((((V0) * (255 - (ALPHA)) + (V1) * (ALPHA)) * 0x101) >> 16) |
| #define BLEND_10BIT(V0, V1, ALPHA) \ |
| ((((V0) * (1020 - (ALPHA)) + (V1) * (ALPHA)) * 0x101) >> 18) |
| |
| 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; |
| if (!has_alpha || pic->a == NULL) return; // nothing to do |
| for (y = 0; y < pic->height; ++y) { |
| // Luma blending |
| uint8_t* const y_ptr = pic->y + y * pic->y_stride; |
| uint8_t* const a_ptr = pic->a + y * pic->a_stride; |
| for (x = 0; x < pic->width; ++x) { |
| const int alpha = a_ptr[x]; |
| if (alpha < 0xff) { |
| y_ptr[x] = BLEND(Y0, y_ptr[x], a_ptr[x]); |
| } |
| } |
| // Chroma blending every even line |
| if ((y & 1) == 0) { |
| uint8_t* const u = pic->u + (y >> 1) * pic->uv_stride; |
| uint8_t* const v = pic->v + (y >> 1) * pic->uv_stride; |
| 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 int alpha = |
| a_ptr[2 * x + 0] + a_ptr[2 * x + 1] + |
| a_ptr2[2 * x + 0] + a_ptr2[2 * x + 1]; |
| u[x] = BLEND_10BIT(U0, u[x], alpha); |
| v[x] = BLEND_10BIT(V0, v[x], alpha); |
| } |
| if (pic->width & 1) { // rightmost pixel |
| const int alpha = 2 * (a_ptr[2 * x + 0] + a_ptr2[2 * x + 0]); |
| u[x] = BLEND_10BIT(U0, u[x], alpha); |
| v[x] = BLEND_10BIT(V0, v[x], alpha); |
| } |
| } |
| memset(a_ptr, 0xff, pic->width); |
| } |
| } 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 |
| |
| //------------------------------------------------------------------------------ |