It depends
Basically, it depends. It depends on how the memory was formatted and what file system it is using. It also depends on whether the actual memory space the photos occupied was overwritten.
Many digital cameras use the FAT or FAT32 file systems. These file systems do not delete files, they simply change the file header leaving the original data intact. If that is all that happened the photos might be able to be recovered (good recovery software can often retrieve files of this nature).
However, if the actual memory location of the photos was overwritten with other data, the pictures are most likely lost. (Depending on many factors, sometimes even this can be recovered.)
If they are very important to you, and you have the cash to spend, I would recommend a data recovery service. They are expensive, but they have the tools and the know-how to recover just about anything if it is possible.
|