Question Mark Appearing on Canon Selphy printer screen
I encountered this issue with a Selphy CP800 and I presume the reason is the same; it seems to be a common problem. Canon tech support says that Selphy printers need exif data "just so" in order to generate screen previews. If all you do is copy your image to a flash memory device from your camera card, you may well be OK. But if you edit the images (e.g. in Photoshop) you will very likely alter the exif data so that Selphy cannot generate previews from flash media plugged into Selphy. If you are copying images back to a **camera** SD card you may also have to make sure that you don't alter the file structure already present on the card. There are undoubtedly other ways to louse up the exif data of an image so that you can't get a screen preview. Workarounds: 1) official Canon advice is to print the image directly from your computer - that's what tech support told me; 2) if you own Canon's Digital Photo Professional Software you can rebuild the exif data by using File>Convert and save>kind of file = exif-jpeg - this worked for me; 3) Graphic Converter for Mac now has a way of rebuilding exif data according to a poster on the Apple discussion boards; I could not test this out b/c my (old) version of Graphic Converter, 5.4, does not have this capability; 4) if you get a screen question mark, the image will still print - you just can't see the preview. This is only a problem if there's more than one image that generates a question mark on your flash media device because you can't see what image you're printing. So if all else fails and you have to print from flash media, you can put a single image with screwy exif data on a flash drive and be confident that you know what you're printing.