How A Photo Breaks

A JPEG has a header at the front that describes the image, then the picture data in order from the top row down. If the header is damaged, nothing opens even though every pixel is still there. If a block in the middle is missing or belongs to another file, the viewer shows the picture correctly to that point and grey or garbage from there. A camera card that was full and busy writes photos in scattered pieces, and a recovery tool that guesses wrong about which piece comes next produces exactly this.

RAW photos from a DSLR, such as CR2 and NEF files, behave much the same, with a bigger header and often a small JPEG preview tucked inside. That preview is sometimes the only whole picture left in a damaged file.

How A Video Breaks

Video is harder. An MP4 or MOV from a phone or camera stores the frames in one part of the file and an index in another, usually at the end, that says where every frame sits and how long it lasts. Cameras write the frames as they record and the index when you press stop. A card pulled out mid-recording, a dead battery or a deleted and partly overwritten clip leaves frames without an index, or an index pointing at the wrong places. The player reads the index, finds nonsense and refuses to play. The footage is largely there.

What Repair Actually Does

DRE Pro repairs damaged photos and videos while the scan runs, not as a separate step afterwards. For a photo, it checks each one as it is found, rebuilds a header where that is the problem and, when a complete picture is hidden inside a broken file, keeps that picture as a file of its own. The repaired file takes the damaged one's place in the results under its name, so the list does not fill with duplicates.

For a video, it follows the clip's own index to find where each frame really sits on the drive, even when the frames are scattered among other files, and puts the clip back in order. Where part of the footage has been overwritten, the rebuilt clip stops at the last real frame. You get a shorter video that plays rather than a long one with someone else's frames spliced in.

What Repair Cannot Do

No jpeg repair tool can invent pixels that were overwritten. If the middle of a photo was reused by another file, that part is gone and the repaired photo shows what remains. The same goes for a video whose frames were overwritten. The marks in the results tell you where you stand before you save. Good means the file checks out. Risky means it opens but part may be damaged. Overwritten means the space was reused and the file cannot come back whole.

Working From A Camera Card

To fix corrupted video files and photos properly, the card they came from has to be scanned. Here is the order that works.

1. Stop shooting on the card the moment something looks wrong. New photos land on the old ones.
2. Put the card in a reader connected straight to the computer and open DRE Pro. The card appears under Drives And Locations as a memory card.
3. Run a Deep Scan. Photos and videos are repaired as they are found.
4. Filter the results to Photos or Videos and preview. Look at the mark on each file.
5. Save to the computer, into a new empty folder, so recovered photos do not mix with ones you already had.