I'm trying to get my Kindle to display some of my photographs as screensavers when it goes into sleep mode. Currently when it goes into sleep mode it displays an ad as a screensaver, so I tried replacing some of them with my photos (I don't want to cheat Amazon out of their ad revenue, I'm leaving most of the ads alone). The screensavers were kept in separate folders on the device and were all titled "screensvr.gif", so I renamed my photo screensvr.gif and replaced the ad with it. Unsurprisingly, it didn't work and I got a screen saying "Please connect to wifi to download latest ads". I had wifi turned off when I did this, so the device had no communication with Amazon's servers. I tried altering the "Date Modified" property of my photo to match that of the ad, and that didn't work either. How does the system know the difference between one "screensvr.gif" and another "screensvr.gif", and how do I make them equivalent in the system's eyes?
Added (1). Yeah, I don't think I'd like the non-ad default screensavers any better. They don't have only one gif file, there's a different one for each ad, and I've verified that they all contain only one image. They're all 600x800, and I've converted my images to that width and height. What do you mean by "custom identifier"? I don't suppose it's anything I could hope to apply to my photos, is it?
Read more: Exactly what information does a.gif file contain?