Corrected the gamma correction in my images. It turns out that I used the Gamma() function for Image Magick incorrectly. Aparently, Gamma(gamma=>2.2) doesn't adjust the image so that it's gamma is 2.2 but in fact, adjust the gamma by a factor of 2.2! This made my photos look really washed out. I didn't notice at first because I was doing the conversion in Linux (I dual boot my mac system MacOS/YellowDog). The photos didn't look too washed out (because the gamma in Linux is usually around 2.5), so I made the mistake of thinking that maybe the default gamma for YellowDog was set the same as the Mac's. It wasn't until I viewed the photos in MacOS that I noticed how terrible they looked. They seemed far more washed out then they normally would if I did the correction in MacOS. So, I went back and instead used Gamma(gamma=>1.2) because going from 1.8 to 2.2 is an adjustment by a factor of about 1.2. This seems to be correct now but I haven't double-checked it yet on a PC system. However, the photos are now slightly lighter on the Mac and seemed slightly darker in Linux, so I think I've got it right this time.