title_body: Is there a standardized or recommended image format, size, and resolution when embedding images?
upvoted_answer: The short answer is no, and I don't expect there to be anything like that with a single recommendation.
  
  The reason is that different input material is better rendered in different image file formats. All material handles well in non-lossy formats (among others most of the TIFF formats, PNG), however such format produce large files. When you look at space saving compressed formats, photos handle well in JPEG, and images of scanned text are best represented in DjVu.
  
  My own experience from scanning mangas drawn on paper (so my daughter can take them on her ebook) are that for that, JPEG is a good format and that I best convert the scan to the physical dimensions of her reader. This gives optimal size of the files. And because of the interpolation that is done on the computer vs the one on the device is of better quality, it looks better and is faster in displaying.
  I noticed this when I had generated her drawings in EPUB form for my reader (with a higher resolution) and then read the same EPUB on hers. The images are combined in a simple EPUB file with the stylesheets setting borders to 0. (I do all calculations for that in pixels, not bothering with physical sizes and resolution, which in the end resolves to the same).