Extract PreviewImage from JPEG (not thumbnail)

[Viper2001]

JPEG files that come from digital cameras often have an additional higher resolution preview image.

I'm testing some Sony A73 and Fuji X-H1 files, and ExifTool tells me there is a PreviewImage like this:

$ exiftool DSC00507.JPG | grep Prev
Preview Image Size : 1616x1080
Preview Image : (Binary data 1050996 bytes, use -b option to extract)

This is a larger preview image in addition to the thumbnail. It'd be great if we can retrieve this preview image from various manufacturers.

Please see forum discussion:
http://dev.exiv2.org/boards/3/topics/3341?r=3371#message-3371

[boardhead]

This is not a small task... There are about a zillion different ways that various camera models store the preview. Fuji seems to be still putting the preview in the archaic FlashPix metadata, while recent Sony models are putting it in the newer MPF metadata. But these are just two possible ways that the preview is stored.

[clanmills]

Ah yes. I know about this and discuss it in my book.

I think we need an intensive effort to deal with this. I don't think it's realistic to undertake this in 2021. I am attempting to either assign open issues to v1.00 or close them. This will have to left remain open for the future. Very desirable future feature.

[8i8]

Hello, I was just wondering if there could be a way of adding an interface to abstract the task of adding new schema for preview images, and to also reuse existing ones? Once done this would make the issue a non issue for future formats. The interesting thing about the preview with my cannon raw/tiff, is that it would appear to be using the tiff format correctly or as was intended; Using the layers that were specifically`1 for this sort of thing.