Today’s Question: I’m having a difficult time wrapping my head around what you said about deleting photos. You said “When you delete photos from a card or (in most cases) when you format the card, the information isn’t actually deleted.” Is that really true? Will deleted photos always remain on my media cards?
Tim’s Quick Answer: It is true that in most cases deleting images from a media card or formatting that card won’t truly remove the information from the card. However, in order to be able to recover the information, you need to be sure not to write new information (photos) to the card.
More Detail: When you delete a file from a media card or other storage device, and in most cases when you format that media, the information contained on the media isn’t truly removed. Instead, the “table of contents” for the media is updated to indicate that the space that had been used for photos or other data is now available for use.
Because of this behavior, it is often possible to recover deleted photos (or other data) from storage media. The most important caveat is that if you write new information to the media, that information will replace the space that had been occupied by the deleted information.
For example, if you capture a single photo on a media card, and then format that media card, you could use special software to recover the photo that had been deleted.
If, on the other hand, you capture a photo, format the card, and then capture a new photo, the would not be able to recover the first photo you captured. This example over-simplifies the situation, but I don’t think the more involved technical details would really be helpful here. The bottom line is that as long as you haven’t written new data to the “empty” space on the media, files that had been deleted can still be recovered.
For many years I’ve been recommending PhotoRescue as a great application for recovering photos from media cards. A free trial enables you to see which photos can be recovered from a given media card, so you don’t have to purchase a license until you know what you’ll be able to recover. You can find PhotoRescue here:
http://www.datarescue.com/photorescue/
Note that some cameras (and most computer operating systems) also include an option to format media in a way that makes it impossible to recover data from the media. For example, some software allows you to perform what is often referred to as a “zero-fill” format, where all available space on the media is filled with the zero character as part of the formatting process. In other words, all “hidden” data is replaced with meaningless data.
But it really is true that as long as you haven’t written new data to storage media, there is a very good chance you’ll be able to recover lost photos or other data from that media using special software such as PhotoRescue.