JpegDigger

JpegDigger recovers deleted and lost JPEG photos from memory cards and drives by reading the raw data rather than the file system. That makes it a carver, the type of recovery tool that ignores whatever a formatted card claims is on it and scans every sector looking for the markers that begin and end a JPEG. It works after a quick format, after files were deleted, and on cards whose file system is too damaged to mount.

Most carvers stop there, grabbing everything between a start marker and an end marker and hoping it is a photo. This one parses the data as it goes, checking that what it found really is valid JPEG structure.

That is how it catches corrupted files before saving them, repairs some of them on the fly, and spots photos that were split into pieces across the card.

Scanning, and reading the entropy map

Pick the card or drive in JpegDigger and start the scan. Found photos fill a list on the right, and selecting one shows its preview, so you can tick only the ones you want before writing anything out. Save them to a different drive, never the card you are recovering from, or you risk overwriting the photos still waiting to be found.

While it scans, an entropy map colours the drive by how random its data looks. Compressed photo data has high entropy, and a card that shows as one flat colour contains nothing but zeros or a repeating pattern.

That means everything was wiped and no tool will bring it back, not even a dedicated card recovery program. It is a fast, honest answer to whether a recovery attempt has any chance.

If nothing turns up, switching off the option that limits the scan to unallocated space is the first thing to try.

Corrupted photos and on-the-fly repair

Photos recovered by simpler tools often open grey halfway down, which is the problem JpegDigger was built around, or refuse to open at all. The repair option fixes violations of the JPEG format so that files at least open and display, flaws included. It does not recreate missing image data, so a photo that lost its lower third stays that way, but a file that would not open anywhere becomes one you can look at.

A skip option leaves out files that are clearly broken, which keeps the results list shorter when you only want clean photos.

Fragmented files and gap carving

Formatting a FAT or exFAT card erases the record of which clusters belong to which file. A photo stored in one continuous run recovers fine. A photo split into two or more pieces comes back as a mess, part image and part something else. Gap carving in JpegDigger tries to find where the first piece ends and where the continuation starts, then stitches them together automatically.

When automatic stitching gets it wrong, a virtual cluster list lets you select clusters by hand within a scan window around the file. Untick the garbage at the end of the first fragment until the image ends cleanly, then tick candidate clusters until the next part appears. It is slow, careful work, but it recovers photos that no ordinary carver can.

For quick undelete jobs on an intact card, a general file undelete tool is faster and simpler.

JPEGs hidden inside RAW files

Many RAW formats, including CR2, NEF, ARW and DNG, carry a full-size JPEG preview embedded inside them. When a RAW recovery tool brings back a corrupted RAW file that no editor will open, this can pull out the embedded full-resolution JPEG instead. You lose the RAW editing latitude, but you keep the picture, at full size, which is often the photo that mattered.

For partition-level problems rather than file-level ones, TestDisk rebuilds lost partitions first.

Conclusion

JpegDigger suits photographers who have formatted the wrong card or lost photos that ordinary recovery software brought back broken. The validation, the on-the-fly repair and the fragment tools address exactly the failures that make other carvers disappointing.

It is a specialist, and it only does JPEG. For a quick undelete on a card that has not been reformatted, a general tool will be faster. When the general tool hands you grey half-photos, this is the one to try next.