Transparency in png format

[amirian]

Any guidelines to solve this problem would be appreciated:
I want to save my converted image via IM to a 4(or 3) bit-depth png format supporting transparency, but I can't: it's bit depth increases to 32 even if I have just one or two colors in the image. Does IM support such a png? This is my final image:


and I want it have the same format as this one(this is not generated by IM):

[amirian]

No comments??!
If impossible in IM, then please introduce a light command line software to convert to 4-bit transparent png format

[fmw42]

best i can suggest is to check out other png tools listed at http://www.imagemagick.org/Usage/formats/#png_non-im

[amirian]

Thanks, I succeeded using pngquant