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avif: new quality settings

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Prior libavif 1.0, quality was set using two numbers
(minQuantizer and maxQuantizer).
New versions of libavif recommend using
new/single quality parameter instead.
Compression using the new settings is different
compared to the old.
For example, new quality 68 gives similar compression
like old default 52.
This commit is contained in:
Daniel Novomeský 2023-12-13 17:40:21 +01:00
parent ce8383e5fd
commit da8ed31aec
1 changed files with 53 additions and 5 deletions
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58
src/imageformats/avif.cpp
View File

@ -16,9 +16,34 @@
#include <cfloat>
/*
Quality range - compression/subsampling
100 - lossless RGB compression
< KIMG_AVIF_QUALITY_BEST, 100 ) - YUV444 color subsampling
< KIMG_AVIF_QUALITY_HIGH, KIMG_AVIF_QUALITY_BEST ) - YUV422 color subsampling
< 0, KIMG_AVIF_QUALITY_HIGH ) - YUV420 color subsampling
< 0, KIMG_AVIF_QUALITY_LOW ) - lossy compression of alpha channel
*/
#ifndef KIMG_AVIF_DEFAULT_QUALITY
#define KIMG_AVIF_DEFAULT_QUALITY 68
#endif
#ifndef KIMG_AVIF_QUALITY_BEST
#define KIMG_AVIF_QUALITY_BEST 90
#endif
#ifndef KIMG_AVIF_QUALITY_HIGH
#define KIMG_AVIF_QUALITY_HIGH 80
#endif
#ifndef KIMG_AVIF_QUALITY_LOW
#define KIMG_AVIF_QUALITY_LOW 51
#endif
QAVIFHandler::QAVIFHandler()
: m_parseState(ParseAvifNotParsed)
, m_quality(52)
, m_quality(KIMG_AVIF_DEFAULT_QUALITY)
, m_container_width(0)
, m_container_height(0)
, m_rawAvifData(AVIF_DATA_EMPTY)
@ -519,9 +544,17 @@ bool QAVIFHandler::write(const QImage &image)
}
}
if (m_quality > 100) {
m_quality = 100;
} else if (m_quality < 0) {
m_quality = KIMG_AVIF_DEFAULT_QUALITY;
}
#if AVIF_VERSION < 1000000
int maxQuantizer = AVIF_QUANTIZER_WORST_QUALITY * (100 - qBound(0, m_quality, 100)) / 100;
int minQuantizer = 0;
int maxQuantizerAlpha = 0;
#endif
avifResult res;
bool save_grayscale; // true - monochrome, false - colors
@ -567,13 +600,15 @@ bool QAVIFHandler::write(const QImage &image)
break;
}
// quality settings
#if AVIF_VERSION < 1000000
// deprecated quality settings
if (maxQuantizer > 20) {
minQuantizer = maxQuantizer - 20;
if (maxQuantizer > 40) { // we decrease quality of alpha channel here
maxQuantizerAlpha = maxQuantizer - 40;
}
}
#endif
if (save_grayscale && !image.hasAlphaChannel()) { // we are going to save grayscale image without alpha channel
if (save_depth > 8) {
@ -646,8 +681,8 @@ bool QAVIFHandler::write(const QImage &image)
QImage tmpcolorimage = image.convertToFormat(tmpformat);
avifPixelFormat pixel_format = AVIF_PIXEL_FORMAT_YUV420;
if (maxQuantizer < 20) {
if (maxQuantizer < 10) {
if (m_quality >= KIMG_AVIF_QUALITY_HIGH) {
if (m_quality >= KIMG_AVIF_QUALITY_BEST) {
pixel_format = AVIF_PIXEL_FORMAT_YUV444; // best quality
} else {
pixel_format = AVIF_PIXEL_FORMAT_YUV422; // high quality
@ -807,6 +842,8 @@ bool QAVIFHandler::write(const QImage &image)
avifRWData raw = AVIF_DATA_EMPTY;
avifEncoder *encoder = avifEncoderCreate();
encoder->maxThreads = qBound(1, QThread::idealThreadCount(), 64);
#if AVIF_VERSION < 1000000
encoder->minQuantizer = minQuantizer;
encoder->maxQuantizer = maxQuantizer;
@ -814,6 +851,17 @@ bool QAVIFHandler::write(const QImage &image)
encoder->minQuantizerAlpha = AVIF_QUANTIZER_LOSSLESS;
encoder->maxQuantizerAlpha = maxQuantizerAlpha;
}
#else
encoder->quality = m_quality;
if (image.hasAlphaChannel()) {
if (m_quality >= KIMG_AVIF_QUALITY_LOW) {
encoder->qualityAlpha = 100;
} else {
encoder->qualityAlpha = 100 - (KIMG_AVIF_QUALITY_LOW - m_quality) / 2;
}
}
#endif
encoder->speed = 6;
@ -870,7 +918,7 @@ void QAVIFHandler::setOption(ImageOption option, const QVariant &value)
if (m_quality > 100) {
m_quality = 100;
} else if (m_quality < 0) {
m_quality = 52;
m_quality = KIMG_AVIF_DEFAULT_QUALITY;
}
return;
default: