looking for simple utility to convert images (jpgs etc.)

[flexy]

problem is..i can very well do that with PSP pro (i mean i am not that stupid - but the problem is that when i convert some jpgs i have, eg. a picture with a white background to a GIF (or PNG) and then set palette transparency the images have an ugly seam.

ALso playing around with noise-filtering etc. doesnt really look that great.

I need a way to eg. set transparency with a certain threshold, and/or maybe there are tools which to that quicker and better as with PSP Pro.

thanks