MacBook Pro (late 2011) graphical glitches

I am seeing regular graphical glitches when previewing JPGs or RAW files within the finder, quick look and picture viewing software. As a photographer this is really constricting my workflow! The issue was evident in OS X Yosemite but has now continued into El Capitan. I am now concerned this is a hardware issue rather than a software issue. My MBP is maxed out at 16Gb RAM and there is sufficient free hard drive space, so I do not believe there is a load issue on the system. Sometimes glitches only occur when viewing an image 100% within an application, sometimes like the below image it is just a simple thumbnail preview. Appreciate any advice. Here is an example of a jpg thumbnail preview with the Finder column view...

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