I think the NIP for long form content, I forget the number but want to say something like 23, stipulates markdown as the format, and markdown has support for image links, so I think you should be fine to use that for inline pictures in a blog post. Note, however, that a lot of clients default to a different NIP, one of the first few, for... I think they call it something like short form text or short notes, and I don't think that requires or expects markdown.