Tuesday, 28 May 2013

Facebook "High Quality" Image Upload

I recently uploaded some holiday snaps to Facebook for everyone to have a look at, and noticed something a bit amiss. I made sure to check the "High quality" checkbox. I made sure I exported the image at a size suitable for Facebook without it having to be resized. And yet the amount of noise added by Facebook's "high quality" image algorithms to produce exactly the same image is mind-boggling.

This is the original, weighing in at 102KB:

And this is the one Facebook delivers to viewers, weighing in at 40KB:

Can you tell the difference? Even when zoomed in? No? Well, I can, because I'm a persnickety perfectionist. And so I did an experiment. Taking each image, overlaying one on top of the other and using a "difference" filter, I produced an image detailing the places where the images differ.

Quite a lot of noise considering it's supposed to be delivering high quality images. But wait, there's more. If I use the Levels slider to increase the overall brightness of the noise image, you'll see that there is hardly a pixel in the image that is not affected by JPEG compression artefacts and blocking.

Bonkers. Of course, I only use Facebook for sharing family snapshots with people in a (relatively) private way. I don't much care if it's a bit low quality. But considering this is the much touted "high quality photo experience" that reckons to given higher resolution and better quality, it's not much to shout about.

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