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


is possible trace image png image jpg? example image x.jpg converted x.png. there way of telling x.png x.jpg, difference being formats?

if l convert img.jpg img.png posssible me img.jpg? intend check in c.

as first question, meta-information stored in png can tell original format or file was. there no requirement store meta-information in file.

as second question: png lossless format. if decompress jpeg image bitmap , encode bitmap png, can @ least th png bitmap of jpeg.

getting jpeg means re-encoding (compressing) bitmap, arrive @ bitwise identical jpeg file means using same compressor settings used create original jpeg. don't know settings (and may depend on compressor code too), "no, can't original jpeg."


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