TinyPNG 的压缩 PNG 算法好厉害

[explon]

https://tinypng.com

一个项目的 PNG 素材体积减少了 70%，支付带透明度的图像

[lalawue]

转成索引色了吧

[jun4rui]

很多PNG压缩以后直接和jpg比尺寸了

[snail1988]

我以前用imageOptim压缩，感觉不错
和这个一比弱爆了

[emric]

确实比同类压缩会高一些.

例如项目中某一张图片:
PS 8.55 KB / Yahoo Smushit 5.98 KB / CssGaga 3.14 KB / TinyPNG 2.66 KB

[ihacku]

http://pngquant.org/

[aaaa007cn]

pngquant 了一下那张 example-orig.png
默认参数的结果是 15.5 KB
然后去官网瞄了下 http://pngquant.org/
>> TinyPNG and Kraken.io — on-line interfaces for pngquant
唉？TinyPNG 就是用的 pngquant？

[snail1988]

@aaaa007cn 貌似真的是pngquant

[GPU]

意思是可以抛弃 jpg ？

[emric]

@aaaa007cn 不, 还是有差距的. pngquant 3.93 KB.

[rainex]

How does it work?
Excellent question! When you upload a PNG (Portable Network Graphics) file, similar colors in your image are combined. This technique is called “quantization”. Because the number of colors is reduced, 24-bit PNG files can be converted to much smaller 8-bit indexed color images. All unnecessary metadata is stripped too. The result: tiny PNG files with 100% support for transparency. Have your cake and eat it too!
---------
是说减少颜色数吧？一般ps或firework输出时有点经验的人都会选择合适的颜色数来减少尺寸的，tinypng比这样处理过的文件还小是么？

[aaaa007cn]

@emric
用的什么参数？即使 --quality 10 结果都有 10KB+ 啊

@snail1988
https://news.ycombinator.com/item?id=4168451
pngquant + optipng + advpng
TinyPNG 还有 40 美刀的 PS 插件出售……
pngquant 本身是 BSD 许可的，也有同样 BSD 许可的免费的 PS 插件 SuperPNG
该说 BSD 许可真好用？Note that both licenses are basically BSD-like; that is, use the code however you like, **as long as you acknowledge its origins**.
虽然我没在 TinyPNG 网站上看到有提到 pngquant
pngquant 官网有写 To further reduce file size use optipng or ImageOptim.
不过 Mozilla 没做 pngquant 和 optipng 合用的测试
https://wiki.mozilla.org/Mobile/Janus#PNG_Compression
不知道还能有多少效果

@rainex
https://news.ycombinator.com/item?id=4168796
关键的还是如何进行矢量量化？
http://pngquant.org/#algorithm
和 PS save for web 的对比
http://pngquant.org/vsphotoshop.html

@GPU
话说 HN 那串 https://news.ycombinator.com/item?id=4167964 有张构造得很巧妙的图

我这里唯一能不显著劣化并减少文件尺寸的方法就是另存为 jpg

[efi]

tinypng可能把图中的关键颜色给优化掉。有时需要pngquant手调参数。