Corrupt CR2 and NEF files due to file fragmentation

By | March 12, 2018

There are many tools available to recover lost or deleted digital photos from memory cards. Most of them are unable to recover non contiguous or fragmented files. As a result fragmented files recovered by such tools will be corrupt.

In such cases JPEG Recovery LAB can help you recover fragmented files. However, recovered files may be corrupt due to other reasons, such as being partially overwritten by new photos.

Typical image corruption after recovery of fragmented photos

This page lists fragmented JPEG, CR2 (Canon RAW files) and NEF (Nikon RAW files) as they typically look after recovery by other photo recovery software.

Assume a file is split in 3 fragments. Fragment 1 accounts for 50% of the data, fragment 2 another 10% and the last fragment contains 40% of the data.

Conventional file recovery and undelete software (assuming a FAT32 or exFAT formatted memory card) will only recover the first fragment, so 50% of the data. The same goes for simple header/footer carving photo recovery software.

JPEG Recovery LAB will find and stitch all file fragments together into one coherent picture.

Protected: JPEG Recovery LAB

JPEG Recovery LAB is only available for professional service providers. To request a demo email joep@disktuna.com.

Overall requirements:

  • Operating system: 64-bit Windows 7 or later with .NET 4.5.
  • CPU: Whatever best desktop CPU you have available. There is no minimum CPU requirement, but processing speed is almost exclusively limited by CPU performance. You can carve the media on a laptop CPU, but it will take longer.
  • RAM: 2 GB per CPU core, 8 GB minimum.
  • An internet connection. JPEG Recovery LAB requires internet access for license validation and telemetry.

CPU selection considerations:

Complex carving is CPU-intensive. Therefore, if you happen to have a choice of several PCs, pick the one with best CPU.

  • Choose server CPUs (Xeon) over desktop CPUs (i5/i7), if you have a server CPU available;
  • Choose higher number of cores. Carving is highly parallelized, therefore more cores directly equates to more performance;
  • Choose CPU with largest possible L2/L3 cache;
  • Only after that, go for highest possible frequency.

JPEG

Contiguous or as recovered by JPEG Recovery LAB

25% of data missing

35% of data missing

Cr2 (Canon RAW)

Contiguous or as recovered by JPEG Recovery LAB

25% of data missing

50% of data missing

Nikon RAW

Contiguous or as recovered by JPEG Recovery LAB

30% missing

Combined Images

Due to file fragmentation file recovery and undelete software may combine parts of different images into one.

Parts of two JPEG files combined into one image

Parts of two Canon RAW files combined into one image. Looks very similar to data missing however pink area starts with obvious corruption!

Two partial NEF files into one

Intact Previews!

Note that previews of these corrupt photos or the image as displayed by “Windows Photos” may look intact! You can use a tool like JpegDigger to ´recover´the JPEG preview files.

Windows Explorer shows intact previews

This corrupt CR2 file looks fine in the Windows Photo App.

These previews can be ´recovered´using a tool like JpegDigger