Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Lossy PNG for true-color images (Velocity Conf ...
Search
Kornel Lesiński
November 18, 2014
Design
2
880
Lossy PNG for true-color images (Velocity Conf EU 2014)
Kornel Lesiński
November 18, 2014
Tweet
Share
More Decks by Kornel Lesiński
See All by Kornel Lesiński
SudWeb
kornel
0
190
Modern PNG compressors
kornel
13
1.2k
Handling binary data in JS
kornel
1
390
Mobblestouch — W3C Touch Events and gestures
kornel
2
720
Server-Sent Events
kornel
5
960
"HTML5" Transport Protocol
kornel
3
380
Front-end Performance
kornel
5
470
Other Decks in Design
See All in Design
Kid Cowboy 103
marilutwin
0
250
業務効率化だけじゃ物足りない AIと一緒にプロトタイプ開発
shingo2000
1
1.5k
AI時代に淘汰されないデザインのしごと
akinen
0
120
バイアスを凌ぐデザインとコード ―異動直後にどうふるまうか―
kkaru
0
430
富山デザイン勉強会_デザイントレンド2025.pdf
keita_yoshikawa
0
310
“使いやすい”が生産性を変える!業務を効率化するためのUX/UI設計ポイント
ncdc
2
380
NAHO SHIMONO_Portfolio2025
nahohphp
0
820
ポートフォリオ_藤田歩希(ほまれ)
akifujita_homarecreate
0
580
セブンデックス カルチャーブック
sevendex
2
16k
AI動画生成ガチャ紹介
piyo7
1
110
タイミーでフィールドワークしたら、サービスデザインが始まった
kenichiota0711
1
1.6k
線で考える画面構成
natsuume
1
870
Featured
See All Featured
What's in a price? How to price your products and services
michaelherold
245
12k
Gamification - CAS2011
davidbonilla
81
5.3k
Build your cross-platform service in a week with App Engine
jlugia
231
18k
Easily Structure & Communicate Ideas using Wireframe
afnizarnur
194
16k
Java REST API Framework Comparison - PWX 2021
mraible
31
8.6k
Performance Is Good for Brains [We Love Speed 2024]
tammyeverts
10
920
Fight the Zombie Pattern Library - RWD Summit 2016
marcelosomers
233
17k
Raft: Consensus for Rubyists
vanstee
140
7k
Making Projects Easy
brettharned
116
6.2k
Adopting Sorbet at Scale
ufuk
77
9.4k
For a Future-Friendly Web
brad_frost
179
9.8k
Designing for Performance
lara
609
69k
Transcript
Lossy PNG Kornel Lesiński 2014
PNG Lossless JPEG Lossy
PNG PNG JPEG Lossless Lossy PNG Opaque Alpha Channel WebP
JPEG 2000 JPEG XR JPEG XT if you need lossy and alpha, it becomes complicated. You may need to serve 4 different files for every image!
flickr.com/photos/ama711/8760361969 0% 100% Lossy PNG is a hack, but it
works like a truly lossy format
Pixels Math gzip Standard PNG
None
gzip finds and removes repeated sequences of identical pixels
00000000 00000001 00000010 00000011 00000100 00000101 00000110 00000111 00001000 00001001
00001010 0 10 110 1110 11110 111110 1111110 11111110 111111110 1111111110 11111111110 → → → → → → → → → → → Instead of storing 8 bits per byte, gzip uses variable-length sequences. Most popular bytes are given shortest sequences.
Some images don’t have repeated pixels and few very popular
colors
0 1 2 3 4 5 6 7 8 9
0 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 = = Instead of storing uncompressible absolute values PNG can store difference between neighboring pixels
5 6 4 6 5 5 6 4 5 4
5 + 1 -2 +2 - 1 0 + 1 -2 + 1 - 1 = = 5 0 0 0 0 0 0 0 0 0 0 Noisy images won’t compress well… unless you fake the data and remove the noise
Pixels Math gzip Lies Lossy PNG trick is about replacing
math with lies. Only the encoder changes, so it’s 100% compatible.
? When PNG “guesses” what the next pixel will be,
it can make the guess based on average of 2 neighbors, which in lossy PNG causes blur
flickr.com/photos/tundra-ice/5124841152 Original: 2MB 0.6MB 0.3MB
Original: 2MB 0.6MB 0.3MB
Original: 221KB Lossy: 67KB ed_g2s
182KB flickr.com/photos/_tar0_/6223343149
27KB flickr.com/photos/_tar0_/6223343149 The algorithm can decide quality of every pixel,
so it tends to preserve sharp edges, especially text
28KB flickr.com/photos/_tar0_/6223343149 Top of the file has 0% quality, bottom
80% quality
• Works everywhere—fully backwards-compatible • No color limit—supports 24 and
32-bit PNG • Preserves edges—per-pixel quality control • Very fast—small tweak in the encoder • Streamable—only needs 2 lines of the image
pngquant -Q 75-100 --skip-if-larger \ -o out.png in.png || posterize
-b -Q 75 in.jpg out.jpg pngquant is often more efficient, but can’t guarantee quality. You can combine the two for best results.
pngmini.com — ImageAlpha GUI github.com/pornel/mediancut-posterizer CLI logicnet.dk/Analyzer — Image Analyzer
GUI @pornelski pngmini.com/lossypng.html