Hi jsmith5379!
The file is just uncompressed to view at your monitor's viewing resolution (75ppi in this case). A 20x30 inch image with a resolution of 75 is actually the same file size as one that is 7.5x5 inches at 300 ppi (pixels per inch). Remember, the file is made up of x number of total pixels derived at by multiplying the width (in pixels) times the length (in pixels). So, the file size remains the same. The size of the file you've noticed indicated in your camera is the "compressed" size. Once you "open" the file, it uncompresses so-to-speak. Confusing, I know. But I hope this helps.
