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Disable some reductions at low levels

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Andrew 2023-05-29 20:43:07 +12:00 committed by Josh Holmer
parent e33a5cfb1d
commit 6cd3783775
1 changed files with 10 additions and 2 deletions
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12
src/reduction/mod.rs
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@ -1,6 +1,7 @@
use crate::evaluate::Evaluator;
use crate::png::PngImage;
use crate::Deadline;
use crate::Deflaters;
use crate::Options;
use std::sync::Arc;
@ -21,6 +22,13 @@ pub(crate) fn perform_reductions(
) -> Arc<PngImage> {
let mut evaluation_added = false;
// At low compression levels, skip some transformations which are less likely to be effective
// This currently affects optimization presets 0-2
let cheap = match opts.deflate {
Deflaters::Libdeflater { compression } => compression < 12 && opts.fast_evaluation,
_ => false,
};
// Interlacing must be processed first in order to evaluate the rest correctly
if let Some(interlacing) = opts.interlace {
if let Some(reduced) = png.change_interlacing(interlacing) {
@ -98,7 +106,7 @@ pub(crate) fn perform_reductions(
// Attempt to convert from indexed to channels
// This may give a better result due to dropping the PLTE chunk
if opts.color_type_reduction && !deadline.passed() {
if !cheap && opts.color_type_reduction && !deadline.passed() {
if let Some(reduced) = indexed_to_channels(&png, opts.grayscale_reduction) {
// This result should not be passed on to subsequent reductions
eval.try_image(Arc::new(reduced));
@ -125,7 +133,7 @@ pub(crate) fn perform_reductions(
}
// Attempt to sort the palette using an alternative method
if opts.palette_reduction && !deadline.passed() {
if !cheap && opts.palette_reduction && !deadline.passed() {
if let Some(reduced) = sorted_palette_battiato(&png) {
eval.try_image(Arc::new(reduced));
evaluation_added = true;