We are not decoding image ourself, rather using ImageIO, if it fails for particular image then no check is performed. Could you, please, attach the image file?

Thank you, does the 'img' element used outside root element?

Please, check that image height/size problem is detected when img is under root tag.

Hmm, do I understand you right:

In 4155 it does only work, when the jsp file is a valid html file and not, as in my case, where the outer tags (html, body, ...) are generated by scriptlets. You fixed that, so the upcoming 4161 version also support that in my case?

To be sure that your problem is fixed please put img tag to the beginning of the jsp file, the width/height problem should be detected.
The problem is fixed in 5.1.1

Yes, when I copy the {{<img src="...">}} line to the top of the line, different widths and heights are detected.

Of course, I meant "top of the file".