iMac Graphics Update fixes an issue that may cause iMac computers to become unresponsive when viewing certain very large JPEG images.
If you're using OS X Yosemite v10.10.3 and one of the following iMac models, viewing certain very large JPEG (.jpg) images in the Finder or Preview can cause your iMac to briefly stop responding, display a black screen, and restart to a message that your computer restarted because of a problem.
