How to index png files?

I have some png files and I would expect Fess can extract text from them.
Then I can make text search.
Is this supported in Fess ?

Yes, Fess utilizes metadata from image files.

Hi shinsuke,

Sorry, I meant the text info to be identified in an image (OCR operation) not the meta data info.
Is it possible to be configured in Fess?

Fess supports Tesseract OCR, but there are no English public documents available.