Parents point is, even if the software to read the format disappears or is much more difficult to run for some reason- if there are published specs, you can recreate it. This is why non proprietary formats are such a great thing.

I would bet that the vast majority if not all image formats that can't be read anymore are due to their spec never being published.

> Survivorship bias

GIF, JPEG, MP3... these are all patented technologies whose patents have expired into the public domain. That they're still used and useful today is a very strong indication that they'll be available in another 50 years. I think that having public patents for image and audio formats helps to demonstrate that it's more than just survivorship bias.

i was going to collate a list, but instead https://www.lemkesoft.info/files/manuals_gc12/GraphicConvert...

That supports 200 image file formats as inputs, and you can then export it to PNG or GIF or BMP.

Your question, on its face, seems ok, but really, there's probably millions of image file formats lost to the sands of time. Shareware image creation programs, tiny fly-by-nite company's software that only ever had one major release (probably some cad formats in there. Those were where i used to always have problems 22 years ago when i did this for work.)

however, at least 200 of them are preserved through that "company's" dedication to this topic.

> How many image formats CAN'T you read today that you could read 50 years ago?

I don’t know. How many?