Digital Image Recovery Utilities
A number of intelligent programs are available for different operating systems
John R. Joyce, Ph.D.
With the proliferation of digital cameras and flash memory drives, instances of data loss in these devices is becoming more frequent. This column recently took a look at disk undelete utilities. In many instances, these same utilities will work to recover files accidentally deleted on solid state memory media. In instances where the data has actually become corrupted, whether through formatting errors or other effects, a new class of utilities comes to the fore.
These can be classified as intelligent file recovery utilities. In addition to having an 'understanding' of the defined disk formats, they also have an intrinsic knowledge of the allowed data file formats. By combining these two libraries of information, the applications can do a much better job of restoring the data. Most of these applications are optimized for the recovery of graphic files, but we also are starting to see ones that support audio and other application formats.
A Web search will turn up a number of these programs for different operating systems. Some are shareware, most are commercial applications. I suspect a number of them are commercialized versions of applications developed for commercial file recovery services. Most of these applications are available as demo versions that typically have the same functionality as the full program, except that they are limited in the number of files they retrieve or in not being able to save the recovered images.
One of the best programs of this type that I've tried is ImageRecall 2.0 ($39.95). Distributed in the U.S. by FlashFixers, it recognizes at least 20 different file formats, ranging from JPEG and PNG to ZIP and MP3, and is available in both Windows and MacIntosh versions. It also includes a unique blend of utility features, the most interesting of which is CD Writer, which allows it to save recovered files directly to CD. Somewhat more expected are Card Check, which can scan for bad memory locations, and Secure Erase, which permanently erases all data from memory cards. This was the slowest program to execute, but the vendor indicated that this was due to the application ignoring the FAT and relying on a detailed scan of the media. The thumbnail viewer of this product seemed the most elaborate of those examined, but did not always function properly in my tests. The viewer's behavior appeared to be operating-system dependent, functioning well under Windows 2000, but not always displaying the thumbnails under Windows ME.
PhotoRescue ($29/$39), from DataRescue Inc., is another strong contender that is available in both Windows and MacIntosh versions. They do provide a performance guarantee, in that once the demo version of the program previews your pictures, the full version will recover your pictures or your money back. It includes the capability to create card images for backup purposes. This program displays the most complete structural information regarding the target media, including such information as the total number of sectors and clusters, cluster size, FAT type, the root directory size and the number of directories found, as well as the number of files found, the number of damaged files, and the number of contiguous files. While the typical user who is just interested in recovering pictures might not care about this information, it helps give a good starting point for those who have to make an effort at manual recovery. Unlike the other programs, it appeared to differentiate between readable files on the media and recovered files, which I found useful. It also has the simplest install, being just an executable file with no registry settings.
The final program I want to highlight today is File-Rescue Plus ($39.95/$44.95) from Software Shelf International. This application, which runs on Windows 95 and above, is a more general file recovery program that includes enhanced photo recovery functionality. It supports FAT12, FAT16, FAT 32, and NTFS directory structures as well as a variety of solid state media. The thumbnail viewer of this product also displayed the file time stamp as well as the name, which could be a very useful feature in verifying that you'd recovered the needed files. This is the only one of the three products you have to relaunch in order to perform another media scan.
A caveat when using these programs is that the amount of data you can expect to recover can be limited by the camera system. If the camera follows the DOS tradition of just erasing the directory entries and marking the clusters as available, then there is a good chance that all of the data can be recovered. The preceding also holds true if the camera performs a traditional DOS-style format. If, instead, it follows the behavior of the Fuji FinePix 3800, and most other Fuji, Sony, and Olympus digital cameras, where an internal format of the media first zeroes all of the media locations, then it is impossible to retrieve any information.
In these tests, all three products were successful at retrieving the file information off the chip. However, I had only a limited number of simple test cases at my disposal. In real life situations, you can get a number of bizarre effects taking place at once. In those cases, it may well be that one of these programs would be more successful than another. As to which program it would be, I suspect that would depend on the specific error. In view of that, if you use digital media extensively, I'd try the demos of all these programs and purchase the one you feel most comfortable with so that it is readily at hand. I'd also keep the other demos handy to try for those instances where you have a data loss and your preferred program won't recover it. At least with these tools, you have the advantage over typical hard disk recovery programs that you are usually dealing with external media and can still safely install the program to your hard drive AFTER the data loss occurs! In the meantime, you might want to review the list of items on the ImageRecall Web site about how to minimize the chances of data losses.
Image Recovery Utility Web Sites
ImageRecall www.imagerecall.com
www.flashfixers.com
PhotoRescue www.datarescue.be
File-Rescue Plus www.softwareshelf.com
John Joyce is the LIMS manager for Virginia's State Division of Consolidated Laboratory Services. He may be contacted at sceditor@scimag.com.
