If I don’t have access to the object that was turned into the PNG in the first place, I do the following:

Open the image file in IrfanView.
Go to Image menu > Resize/Resample.
Pick a percentage for a new size that changes the image by a number that’s the quotient of two small integers.
For example, 75% (3/4) or 80% (4/5) are better than 78%. This isn’t as critical as it once was.
Use the resample not resize method.

Then I save the new image with a new name. I always retain the original without adulterating it.

It may take some experimenting to get it to look okay.

Once it’s encoded in JPG, the damage has been done. Your choices are to leave it as a JPG, or recreate it from the original as PNG.

My bad. I must have been looking at an older image file, which never got uploaded. The JPG image is 6141 bytes.

Tim & Teylyn -

I rarely use transparent images in my web site anymore. My pages are white, my image backgrounds are generally white. On the rare occasions I need a transparent image, I rely on the trusty old GIF format.

I’ve never had a problem with a PNG not being visible in my browser (I’ve switched to Firefox, but used IE6 until about six months ago), and no readers have complained about it.

Right. Absolutely correct.

And in some cases the ancient GIF format is even better than PNG. Especially when using transparency and tartetting an audience that may still be using Internet Explorer 6. This browser, which is still very common out there, does not fully support transparency in PNGs and has some other issues with the format, too, so sticking to good old GIF gives you a higher probability that your page will show up on their browser the way you intend it to look.

So despite all the wonderful things that you can do with PNGs, there’s a slight risk that your viewer won’t see it.