Convert obsidian type markdown to normal markdown For me
In obsidian markdown, it is ![[path]]. This tool replace it 
This is written <img src="path" /> in HTML.
Target picture file extentions are "jpeg", "jpg", "png", "gif", "bmp", "webp", "tiff", "apng".
You will be able to add some picture extentions. I don't implement now.
In obsidian app view, new line is enabled, but normal markdown ignore new line. So add " " (two spaces) before new line char like \n or \r\n.