I think that simply asking the question, what was the impact of photography on the world of fine arts and graphic designs do not quite grasp the full reality of how photography really altered the world in how we know it now. Since the invention of photography the world of graphic design and fine arts has just shot off the map. Before photography artist had to deal with people posing and they were forced to work with objects that were always moving. Artist could never get a 100% still shot to try and re-create on a canvas. After painting came about artist were able to see a completely still shot and were able to produce more consistency in there painting.
On the other hand since the invention of photography fine artist were not needed like they were before. Families could just go have there portrait taken with a camera instead of paying an artist to paint there family. But fine artist were needed to produce a quality picture with a camera also. The right background and poses were needed.
Graphic design has reached above and beyond what was ever dreamed of because of photography. Graphic artist are now able to take a picture and re-arrange it to make something else or move objects in the picture to create a certain need like advertising for example. Graphic artist are able to take numerous pictures of different objects/products and place them in a magazine ad for people to compare and contrast with very high accuracy of what the product actually looks like in real time. So the real question we should be asking ourselves is not what was the impact of photography but rather what was NOT impacted by the invention of photography.