I'm not the OP, but I've had trouble with the JPEGOptim feature of ImageOptim. It created JPEG files that crashed the JPEG decoder on some older android phones.
The files worked fine elsewhere, so I think it was an decoder bug not an invalid file, but I had to avoid optimizing JPEG files to avoid the problem.
This was about two years ago, so I don't recall version numbers or phone models.
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"Selective JPEG Compression" was a new one for me.
For PNG, always run your images through ImageOptim (http://imageoptim.com) before committing your work.
And for large PNGs, ImageAlpha (http://pngmini.com) lets you reduce bit depth, keep transparency and maintain a decent image quality.
Why only PNG?
I'm not the OP, but I've had trouble with the JPEGOptim feature of ImageOptim. It created JPEG files that crashed the JPEG decoder on some older android phones.
The files worked fine elsewhere, so I think it was an decoder bug not an invalid file, but I had to avoid optimizing JPEG files to avoid the problem.
This was about two years ago, so I don't recall version numbers or phone models.
Anecdotally, I find the best image compression using ImageOptim for PNGs and JPEGmini for JPGs. However, ImageOptim can also compress JPGs.