a large number of PNG images are used in the Cocos Project, and the PNG file size typically accounts for about 90% of the size of the release package, and compressing the PNG file size plays a key role in reducing the size of the release package.
we know that PNG files can be roughly divided into three formats: PNG32, PNG24, PNG8. Color richness (picture quality) from high to low, file size is also from large to small. Art from the PS, Maya and other tools to export pictures are usually the PNG32 format, the usual practice is to use fireworks and other tools between PNG32 into the PNG8 format.
here we recommend a PNG image compression tool, named: Pngyu. : http://nukesaq88.github.io/Pngyu/
Pngyu can batch PNG32 format picture file into PNG8 format, and it will use a set of image compression algorithm, so that the converted image quality distortion is not so serious (the specific picture loss situation, we can feel about it, this with the art to do a diagram also has a certain relationship, Plainly, it is related to the number of colors used in art, the less the number the better. Most importantly, the converted image file size is only about 35% before conversion, which is quite impressive.
However, the software in the use of the process also has a point to note, with a translucent effect, and a color gradient of the picture, after compression will appear very serious ripples, which is mainly PNG8 the number of colors he less caused (mishap, no way), So this kind of picture still honestly use PNG32 format bar (this kind of picture usually not too big), also have the art to do effect time, try to avoid this kind of expression technique.
There is also a small suggestion, you can finish the atlas, then use Pngyu to compress the final Atlas file:)
Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.
PNG image compression Tool recommended-----Pngyu
