Open Radar

 
Summary:
When uploading crisp and clean 1440-by-900 pixel screenshots (in png format) for a Mac App Store app to iTunes Connect, the screenshots displayed in the Mac App Store show artifacts of jpg compression and are blurry. The images are downsampled to 800-by-500 which is fine but the quality of the screenshots is terrible. In particular, pixels in flat-color areas close to text look terrible. Some example screenshots are here:
 
https://www.dropbox.com/sh/stzosuh7rm33zla/AAC4AbVRvd4sEjQ0Pie55Dw_a?dl=0
 
v1 and v2 are identical, this is the screenshot as uploaded and downloaded from iTunes Connect
v3 is a screenshot taken from the App Store app on my mac (OSX 10.10.1, App Store app 2.0 (376.0.5) on a 24 inch display (standard resolution)
v4 is the image directly taken from the Mac App Store app preview (webpage), which is in fact a jpg file
v5 is what I get if I take v1 and scale it to 800-by-500 in Preview, this is much better than v3 or v4
v6 is what I get if I take v5 and save it as jpg with the highest quality setting, again much better than v3 or v4
v7 is what the image looks like in the App Store while resizing the window. It is crisp but also shows compression artifacts.

It would appear that this is probably easy to fix. It should also be high priority since Apple prides itself with the design of its products.

Steps to Reproduce:
Look at the screenshots of any app in the Mac App Store. If necessary, zoom in sufficiently. Look at pixels around text (on flat background color) for most prononunced effects.