Not sure I understand the question. If you have ever seen a ground glass on the back of a view camera, you will see the image is reversed right to left, and top to bottom. This is how the image is "burned" onto film. So if you were to look at the emulsion side of the film, the image would appear as a mirror image. Viewing from the back side of the film, it appears correctly as the image originally was. When printing, the emulsion of the neg is facing down, and light comes from the back side of the film, thereby making a positive print. Does this answer the question?