Lady, EVOLVED 
is an animated gif an image?
why is an animated gif an image?
@Lady I chose 'intended to be perceived visually' because that's the closest to my reasoning. But my exact reasoning is more like 'labelling it as video seems inaccurate, because it has no audio capability, and it seems excessive to come up with an entirely new category like 'animated image' just to accomodate the idea of an image format with no audio channel (especially since it's just this one format that constitutes most if not all of this category of file formats on the web).
@Lady Oh, also gifs are intended to be used as either static or animated images, so it wouldn't be entirely accurate to use a format type that implied the sole intent of the format was for animation.
@unspeakablehorror why do all gifs have to have the same format type?
@Lady Seems more of a hassle to split them up than just have one single format. Also seems excessive to have a whole type that would be devoted almost entirely if not exclusively to one file format.
@unspeakablehorror on mastodon gifs are actually served as webm format. do you think that is fundamentally a different type of thing just because it isn't image/gif?
@Lady Yes, because the format itself allows audio. To me it's not about any given usecase for a format, but the format's capabilities as a whole
@unspeakablehorror what about physical resources? is a polaroid not be an image, because it has no computerized encoding?
@Lady Sure, it's an image. I guess the question is, is the intent of this category to be used as a formalized labelling (eg. a mimetype) or informally? Because formally, I'd consider gifs images but informally I'm happy to distinguish between an animated gif and a static one.
@unspeakablehorror personally i would say a polaroid is formally an image, not just informally :P
@Lady True. The question of the intent of the categorization still stands though. Is the purpose to be part of a dictionary definition, a formal specification like a mimetype, as use in casual conversation, or something else entirely? The context is relevant for determining what categorization(s) I would use.
@unspeakablehorror i think it is a formal specification, but one that encompasses physical resources in addition to digital ones
@Lady So not a mimetype, then. I'd need more details about the purpose of the specification to know how I'd categorize it, then. Is it for putting in a dictionary to formally define words for definitional purposes, or is there some other different or additional purpose to the categorization?
@unspeakablehorror let’s say it’s so that when users filter their search to only show images, they get back a list which only shows images
@Lady In that case, I'd say there's more than one fairly reasonable choice. Depends on how much work you're willing to do for it. If the goal is a low effort implementation that exhaustively shows all images, then yes, I think considering animated gifs as images is the way to go. If the amount of effort required for the implementation isn't a consideration, then no, I'd give them a separate category like 'short animation' and reserve 'image' for static images.
@Lady for example gif, png, mp3, mp4, avi, webm. Each of these is a type of computerized encoding that has a certain set of capabilities that implies a certain intent they are particularly suited for. Collectively they can fit into larger subtypes which the mimetype is used to indicate.