how to automatic reduce png colors?

[fuchaoqun]

Dears,

I have a png file here:

http://img.hixue.com/test/p1.png

It's so big, I use fireworks to rebuild its color table, and it got much smaller, how can I use imagemagick to reduce the image file size? It seems that the file only have some unique colors, less than 256.

Thanks very much.

[fuchaoqun]

the optimized png file is here: http://img.hixue.com/test/p11.png

how can i use imagemagick to do it?

[fmw42]

see http://www.imagemagick.org/Usage/formats/#png_quality

or

http://www.imagemagick.org/Usage/formats/#png_non-im

[fuchaoqun]

Dear fmw42,

I have tried those tools, but I can not work it out? can you give me a command that I can convert p1.png to the size of p11.png without lose much quality

there are many gray and truecolor images, so I can not just set them gray.

[fmw42]

sorry I am not an expert on optimizing png. I have been told that optipng is one of the better tools.

[fuchaoqun]

thanks, can somebody help me to fix it?

[fmw42]

you can convert to png or gif with reduced number of colors and get about the same filesize as your optimized png


convert p1.png -colors 16 p1_c16.gif

convert p1.png -colors 16 p1_c16.png

[fuchaoqun]

there are turecolor and gray images, I can not just set the same color numbers.