C#: Take Out Image Portion of JPEG to Backup Metadata?

This will be a little backwards from the typical approach.

I've used ExifTool for metadata manipulation before, but I really want to keep the best metadata backup I can before I make anything permanent.

What I want to do is remove t开发者_开发问答he compressed image portion of a JPEG file to leave everything else intact. That's backing up EXIF, Makernotes, IPTC, XMP, etc whether at the beginning or end of the file.

What I've tried so far is to strip all metadata from a copy of the original JPEG, and use it as a basis of what bytes will be taken out of the original. After looking at the raw data, it doesn't seem like the stripped copy is contiguous in the original copy. There may be some header information still remaining in the stripped version. I don't really know. Not a good way to do it, I suppose.

Are there any markers that will absolutely tell me where the compressed JPEG image data starts and ends? I understand that JPEG files have 0xFFD8 and 0xFFD9 to mark the start and end of the image, but have come to find out that metadata is actually between those markers.

I'm using C#.

Thank you.

To do this properly you need to fully parse the JPEG/JFIF format and discard anything you don't want. Metadata is all kept in APP segments or trailers after the JPEG EOI, so presumably you will toss everything else. Full parsing of a JPEG/JFIF is not trivial, and for this I refer you to the JPEF/JFIF specification.

You can use the JpegSegmentReader class from my MetadataExtractor library to retrieve specific segments from a JPEG image.