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fix rescaling-with-alpha inaccuracy

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(still missing YUVA decoding case for now)

https://code.google.com/p/webp/issues/detail?id=160

Change-Id: If723b4a5c0a303d0853ec9d839f995adce056095
This commit is contained in:
Pascal Massimino
2013-07-26 12:05:42 -07:00
committed by skal
parent 11249abfc7
commit 8dcae8b3cf
10 changed files with 342 additions and 37 deletions
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64
src/dec/vp8l.c
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@ -18,6 +18,7 @@
#include "./vp8li.h"
#include "../dsp/lossless.h"
#include "../dsp/yuv.h"
#include "../utils/alpha_processing.h"
#include "../utils/huffman.h"
#include "../utils/utils.h"
@ -417,12 +418,13 @@ static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) {
// We have special "export" function since we need to convert from BGRA
static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace,
int rgba_stride, uint8_t* const rgba) {
const uint32_t* const src = (const uint32_t*)rescaler->dst;
uint32_t* const src = (uint32_t*)rescaler->dst;
const int dst_width = rescaler->dst_width;
int num_lines_out = 0;
while (WebPRescalerHasPendingOutput(rescaler)) {
uint8_t* const dst = rgba + num_lines_out * rgba_stride;
WebPRescalerExportRow(rescaler);
WebPMultARGBRow(src, dst_width, 1);
VP8LConvertFromBGRA(src, dst_width, colorspace, dst);
++num_lines_out;
}
@ -430,18 +432,22 @@ static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace,
}
// Emit scaled rows.
static int EmitRescaledRows(const VP8LDecoder* const dec,
const uint32_t* const data, int in_stride, int mb_h,
static int EmitRescaledRowsRGBA(const VP8LDecoder* const dec,
uint8_t* in, int in_stride, int mb_h,
uint8_t* const out, int out_stride) {
const WEBP_CSP_MODE colorspace = dec->output_->colorspace;
const uint8_t* const in = (const uint8_t*)data;
int num_lines_in = 0;
int num_lines_out = 0;
while (num_lines_in < mb_h) {
const uint8_t* const row_in = in + num_lines_in * in_stride;
uint8_t* const row_in = in + num_lines_in * in_stride;
uint8_t* const row_out = out + num_lines_out * out_stride;
num_lines_in += WebPRescalerImport(dec->rescaler, mb_h - num_lines_in,
row_in, in_stride);
const int lines_left = mb_h - num_lines_in;
const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
assert(needed_lines > 0 && needed_lines <= lines_left);
WebPMultARGBRows(row_in, in_stride,
dec->rescaler->src_width, needed_lines, 0);
WebPRescalerImport(dec->rescaler, lines_left, row_in, in_stride);
num_lines_in += needed_lines;
num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out);
}
return num_lines_out;
@ -449,11 +455,10 @@ static int EmitRescaledRows(const VP8LDecoder* const dec,
// Emit rows without any scaling.
static int EmitRows(WEBP_CSP_MODE colorspace,
const uint32_t* const data, int in_stride,
const uint8_t* row_in, int in_stride,
int mb_w, int mb_h,
uint8_t* const out, int out_stride) {
int lines = mb_h;
const uint8_t* row_in = (const uint8_t*)data;
uint8_t* row_out = out;
while (lines-- > 0) {
VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out);
@ -530,11 +535,12 @@ static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos,
static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) {
WebPRescaler* const rescaler = dec->rescaler;
const uint32_t* const src = (const uint32_t*)rescaler->dst;
uint32_t* const src = (uint32_t*)rescaler->dst;
const int dst_width = rescaler->dst_width;
int num_lines_out = 0;
while (WebPRescalerHasPendingOutput(rescaler)) {
WebPRescalerExportRow(rescaler);
WebPMultARGBRow(src, dst_width, 1);
ConvertToYUVA(src, dst_width, y_pos, dec->output_);
++y_pos;
++num_lines_out;
@ -543,28 +549,28 @@ static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) {
}
static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec,
const uint32_t* const data,
int in_stride, int mb_h) {
const uint8_t* const in = (const uint8_t*)data;
uint8_t* in, int in_stride, int mb_h) {
int num_lines_in = 0;
int y_pos = dec->last_out_row_;
while (num_lines_in < mb_h) {
const uint8_t* const row_in = in + num_lines_in * in_stride;
num_lines_in += WebPRescalerImport(dec->rescaler, mb_h - num_lines_in,
row_in, in_stride);
const int lines_left = mb_h - num_lines_in;
const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
WebPMultARGBRows(in, in_stride, dec->rescaler->src_width, needed_lines, 0);
WebPRescalerImport(dec->rescaler, lines_left, in, in_stride);
num_lines_in += needed_lines;
in += needed_lines * in_stride;
y_pos += ExportYUVA(dec, y_pos);
}
return y_pos;
}
static int EmitRowsYUVA(const VP8LDecoder* const dec,
const uint32_t* const data, int in_stride,
const uint8_t* in, int in_stride,
int mb_w, int num_rows) {
int y_pos = dec->last_out_row_;
const uint8_t* row_in = (const uint8_t*)data;
while (num_rows-- > 0) {
ConvertToYUVA((const uint32_t*)row_in, mb_w, y_pos, dec->output_);
row_in += in_stride;
ConvertToYUVA((const uint32_t*)in, mb_w, y_pos, dec->output_);
in += in_stride;
++y_pos;
}
return y_pos;
@ -575,11 +581,11 @@ static int EmitRowsYUVA(const VP8LDecoder* const dec,
// Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and
// crop options. Also updates the input data pointer, so that it points to the
// start of the cropped window.
// Note that 'pixel_stride' is in units of 'uint32_t' (and not 'bytes).
// start of the cropped window. Note that pixels are in ARGB format even if
// 'in_data' is uint8_t*.
// Returns true if the crop window is not empty.
static int SetCropWindow(VP8Io* const io, int y_start, int y_end,
const uint32_t** const in_data, int pixel_stride) {
uint8_t** const in_data, int pixel_stride) {
assert(y_start < y_end);
assert(io->crop_left < io->crop_right);
if (y_end > io->crop_bottom) {
@ -588,11 +594,11 @@ static int SetCropWindow(VP8Io* const io, int y_start, int y_end,
if (y_start < io->crop_top) {
const int delta = io->crop_top - y_start;
y_start = io->crop_top;
*in_data += pixel_stride * delta;
*in_data += delta * pixel_stride;
}
if (y_start >= y_end) return 0; // Crop window is empty.
*in_data += io->crop_left;
*in_data += io->crop_left * sizeof(uint32_t);
io->mb_y = y_start - io->crop_top;
io->mb_w = io->crop_right - io->crop_left;
@ -666,17 +672,17 @@ static void ProcessRows(VP8LDecoder* const dec, int row) {
// Emit output.
{
VP8Io* const io = dec->io_;
const uint32_t* rows_data = dec->argb_cache_;
if (!SetCropWindow(io, dec->last_row_, row, &rows_data, io->width)) {
uint8_t* rows_data = (uint8_t*)dec->argb_cache_;
const int in_stride = io->width * sizeof(uint32_t); // in unit of RGBA
if (!SetCropWindow(io, dec->last_row_, row, &rows_data, in_stride)) {
// Nothing to output (this time).
} else {
const WebPDecBuffer* const output = dec->output_;
const int in_stride = io->width * sizeof(*rows_data);
if (output->colorspace < MODE_YUV) { // convert to RGBA
const WebPRGBABuffer* const buf = &output->u.RGBA;
uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride;
const int num_rows_out = io->use_scaling ?
EmitRescaledRows(dec, rows_data, in_stride, io->mb_h,
EmitRescaledRowsRGBA(dec, rows_data, in_stride, io->mb_h,
rgba, buf->stride) :
EmitRows(output->colorspace, rows_data, in_stride,
io->mb_w, io->mb_h, rgba, buf->stride);