printersolved wrote:
A few practical notes for anyone landing here with damaged CR2s that weren't caused by bad sectors:
1. Know what's inside. CR2 is a TIFF-based container. IFD0 holds a large embedded JPEG preview plus EXIF, IFD1 a small thumbnail, IFD2 a small uncompressed RGB image, and IFD3 the actual raw data (lossless-JPEG compressed). Damage to the raw strip doesn't necessarily touch the preview, and vice versa.
2. Check the start of the file first. A healthy CR2 starts with 49 49 2A 00 ("II*") and has 43 52 ("CR") at offset 8. If the first sectors are zeros or belong to another file, the file was allocated wrongly (typical after undelete or a damaged FAT), not "corrupted".
3. Pull the preview before trying anything else. exiftool -b -PreviewImage file.CR2 > file_preview.jpg (or -JpgFromRaw). On most Canon bodies that preview is full-size or close to it, and it's often intact when the raw data isn't. That's all the "CR2 repair" tools really do.
4. Header grafting only works with a matching donor: same body, same image size/quality setting, ideally the same firmware. Copy the donor's header up to the raw strip offset (StripOffsets in IFD3), keep the damaged file's raw data, and fix StripByteCounts if the sizes differ. Then test the decode with dcraw -v -T or LibRaw's raw-identify. Corruption in the lossless-JPEG stream shows as a smear or shift from the damaged point down, and no tool can rebuild that part.
5. If many files are broken the same way, look at the card or file system, not the files. Fragmented exFAT allocations on a card that was written by a different device are a classic cause, and carving with a camera-aware tool (CR2 files are usually contiguous on the card) gives better results than repairing extracted copies.
Another ID10T not reading or incapable of processing what was written in the thread.
_________________
Joep -
http://www.disktuna.com - video & photo repair & recovery service
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