This image is 1200px across, twice the size of the click through images, which seem to have a standard size of 600px. So, when I click through on the thumbnail, will I get a huge image, or just the standard 600px wide image... Let's see. Aha! The image is compressed!! This is the first time I've seen Pinterest alter the clickthrough image. Bottom line, no matter how large your images are above 600px, Pinterest will compress is to 600px. Images under 600px are left alone.