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fix rescaler vertical interpolation

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* vertical expansion now uses bilinear interpolation
  * heavily assumes that the alpha plane is decoded in full, not row-by-row
  * split the RescalerExportRow and RescalerImportRow methods into Shrink
    and Expand variants.
  * MIPS implementation of ExportRowExpand is missing.

There's room for extra speed optim and code re-org, but let's keep that for later patches.

addresses https://code.google.com/p/webp/issues/detail?id=254

Change-Id: I8f12b855342bf07dd467fe85e4fde5fd814effdb
This commit is contained in:
Pascal Massimino
2015-09-18 10:45:03 +02:00
committed by James Zern
parent cd82440ec7
commit 5ff0079ece
10 changed files with 553 additions and 388 deletions
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8
src/dec/vp8l.c
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@ -420,7 +420,7 @@ static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) {
const int in_height = io->mb_h;
const int out_height = io->scaled_height;
const uint64_t work_size = 2 * num_channels * (uint64_t)out_width;
int32_t* work; // Rescaler work area.
rescaler_t* work; // Rescaler work area.
const uint64_t scaled_data_size = (uint64_t)out_width;
uint32_t* scaled_data; // Temporary storage for scaled BGRA data.
const uint64_t memory_size = sizeof(*dec->rescaler) +
@ -436,7 +436,7 @@ static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) {
dec->rescaler = (WebPRescaler*)memory;
memory += sizeof(*dec->rescaler);
work = (int32_t*)memory;
work = (rescaler_t*)memory;
memory += work_size * sizeof(*work);
scaled_data = (uint32_t*)memory;
@ -456,7 +456,7 @@ static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace,
int num_lines_out = 0;
while (WebPRescalerHasPendingOutput(rescaler)) {
uint8_t* const dst = rgba + num_lines_out * rgba_stride;
WebPRescalerExportRow(rescaler, 0);
WebPRescalerExportRow(rescaler);
WebPMultARGBRow(src, dst_width, 1);
VP8LConvertFromBGRA(src, dst_width, colorspace, dst);
++num_lines_out;
@ -574,7 +574,7 @@ static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) {
const int dst_width = rescaler->dst_width;
int num_lines_out = 0;
while (WebPRescalerHasPendingOutput(rescaler)) {
WebPRescalerExportRow(rescaler, 0);
WebPRescalerExportRow(rescaler);
WebPMultARGBRow(src, dst_width, 1);
ConvertToYUVA(src, dst_width, y_pos, dec->output_);
++y_pos;