Q: when trying to download photos  from my digital cameras I keep getting the message that pics can't be downloaded because of an unrecognizable format. It shows that they are all jpeg files. One camera is a Canon, the other a Panasonic.

As a Test:

Hold down the option (or alt) key and launch iPhoto. From the resulting menu select 'Create Library'

Import a few pics into this new, blank library. Is the Problem repeated there?

Post back with the result.

Same problem as jimmoul...

OS X 10.9.2

IPhoto 9.5.1

Never encountered this problem before, just returned from vacation with new pictures. I am able to view pictures on my Camera display only, files appear as JPEG icons when camera connected to macbook (or memory card inserted directly into reader), when imported error message appears stating files are of unrecognizable format precluding import.

I was able to download jpeg files to desktop, however the files cannot be viewed/opened as they are not recognized by Preview or other apps...

I tried importing files from memory card directly as well as desktop files to newly created iphoto library, which was unsuccesfull (same issue as above)

I downloaded card raider recovery from App store, & the app did not identify any files on the card (scan attempted with card both locked and unlocked), which I thought was odd...

It appears to be a memory card issue...I inserted a new card into same camera, took several pictures and had no difficulty importing photos...

Just wondering if there are anyoptions at this point to recover pictures, any advice would be greatly appreciated...

If the memory card is corrupted I don't think there's any way to "recover" the photos in an uncorrupted state. 

Try the demo version of GraphicConverted to see if it can open and display those files.  If it can save it as a new file and import into iPhoto.

OT

I am having the same problem which has happened very infrequently before. Generally it's one photo and happened when my battery died.

However today I tried to download six photos.

None would download including several others for a total of 21 that would not download.

Since I had just installed a new powered hub and added three new external 4T hard drives, I got concerned that it was the hub. Then got really worried that I'd have problems with the data I have been backing up.

However following this sequence of events, I've determined it's not the hub, but still don't know what is causing the problem.

(1) Put a fresh battery in the camera - same results

(1.5) Used a different port in the new hub - same results

(2) Put the card in the card slot in the back of my iMac - no problems except that one image I knew about last week. The six new images imported.

(3) Tried again using the cable - still same error

(4) Changed cables - my husband has the same camera - still same error

(4) Put the card in his camera with his cable - still same error

(5) Put the card in a card reader and used the same slot in the new hub - no problems - same one wouldn't import but message that there are no new photos to import.

(6) Moved the offending one image to the Trash while the card was in the card reader

(7) Put the card back into my camera and used my cable. iPhoto had no error and displayed the message there are no new photos.

Conclusion:

Not the camera

Not the cable

Not the hub

Must remove bad photo from the card

However, I have not had to do that before. I went through several imports on vacation when there was one bad image and just ignored it each time.

Any idea why this is happening now?

Thank you

I should have mentioned that the corrupted image was DSCN4099 while the next 20 that would not imported were DSCN4139-4157.

They were not immediately after the bad one.