I want to test the unity engine by making a simple 2d platformer level with graphics from Sonic so I ripped the graphics from the game into a .bmp file which I have attached to this post. So what I do is I click on add new tileset, set type to "Based on tileset image" and then set tile size to 8x8 pixels. And once I do that it says "Failed to load tile image"
Have you tried other formats? I remember some map editing tools only taking PNG.
EDIT: I hope you know that Sonic 1 maps aren't built with free placement of 8x8 tiles, but instead of 256x256-pixel chunks made of 16x16-pixel metatiles. That's kind of important to make such large levels possible.
Well, it worked with the PNG, but I don't know why tiled was so picky with this bitmap image, it worked with other bitmaps, and a bunch of other online conversion tools I used to convert my bitmap to PNG wouldn't work with that file. Could it be because those online tools just suck? I doubt it, because even though they're usually filled with ads, they tend to get the job done. I just don't know why all of these tools wouldn't work with my file. Would any of you guys know why? I attached the actual file as an experiment to see if it worked with php which it seems to do just fine.
BMP files come in lots of different flavours, it is probably only set up to load one particular format that BMP can do (e.g. RGB24) and has poor error messages to explain when it can't load a different format.
I remember using a Genesis emulator that saved the VRAM contents as a 16-color BMP, which some applications might not like. Maybe that's what you did?