some software to reduce png file size without altering much its quality?

been searching for long but cudnt find a descent one

The simplest way would be resizing it in width and height without loosing too much quality.

i want to keep the canvas size as it is, yet i want to reduce the file size at least 50% so the sigs can fit into the jsp sig rules

in that case I would say no. if you want to reduce 50% size of the file without rezizing canvas or image it would lose really much quality.

just change it to a gif, then it will be about 50% of the size

well gif doesnt seem to support well the transparency. a pop out sig in gif format will just look like shit

no1 knows?

if 256 colors enough save it as gif