CODEWITHSUNDEEP
cimageformat
Mutai Mwiti
Mutai Mwiti

Reputation: 487

How to discover an image that was converted from one format to anothter?

Is it possible to trace back an image say a png image to a jpg? For example an image x.jpg that was converted to x.png. Is there a way of telling that x.png is essentially x.jpg, with the difference being formats?

If l convert img.jpg to img.png is it posssible for me to get back img.jpg? I intend to check this in C.

Upvotes: 1

Views: 44

Answers (1)

Paul Ogilvie
Paul Ogilvie

Reputation: 25286

As to your first question, the meta-information stored in PNG can tell what the original format or file was. But there is no requirement to store this meta-information in the file.

As to your second question: PNG is a lossless format. So if you decompress a Jpeg image into a bitmap and then encode that bitmap as PNG, you can at least get back from th PNG to the bitmap of the jpeg.

Getting back to the jpeg essentially means re-encoding (compressing) the bitmap, but to arrive at the bitwise identical Jpeg file means using the same compressor settings that were used to create the original Jpeg. As you probably don't know those settings (and it may depend on the compressor code too), I would say "No, you can't get back to the original Jpeg."

Upvotes: 2

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