Recovered "Excellent" files do not open

I used Recuva FREE to find files on a bad CF memory card used in a Canon camera. It found 800+ jpeg files as being "Excellent" so I selected all of them and clicked RECOVER. The recovered files will not open in Windows or PhotoShop. These recovered files have jpg as file type and appropriate file sizes in the 4-5 MB range. The file names are unusual with an underscore and a bracket in them (e.g., _IG[4010 and IIG[8310). Help!!

Excellent means that there is no conflict between the file clusters and any other live file clusters (I don't know about any other deleted file clusters). The underscore for the first char is FAT's way of denoting a deleted file.

Recuva will recover whatever data is in the file clusters. The data may have been overwritten several times by other files that have subsequently been deleted. FAT tables also keep a list of all the clusters in ascending order. If a file has been fragmented, as is possible with 4 to 5 mb files, then the chains linking the cluster fragments in the FAT can be broken on file deletion, leading to invalid data being recovered.