Question posted in 
Can’t directly take screenshots from an iPad simulator/device. Thus, resorting to rescaling crisp iPhone screenshots into iPad screenshots. The results are minor width stretching.
1242×2208 (iPhone 5.5″) is rescaled into 2048×2732 (iPad 12.9″) using ‘nearest neighbor (preserve hard edges)’ in photoshop resampling.
Currently I don’t mind because the specific iPhone screenshots were very hard to capture & I need them the way they are; replicating them through the simulator/device would be impossible, especially for the iPad.
Will apple have issues with this during review process & reject the app?
Or it doesn’t matter?
2
Answers
So I risked it & attached re-scaled iPhone screenshots as iPad screenshots into iTunes Connect. The app passed the app review process with no problems & is now released into the App Store. Just to clarify, as Mark Thormann has already pointed out, variation is allowed BUT "pixel dimensions do have to meet requirements"!
I can’t speak exactly to the original question about the App Store but I’ve found that they allow some significant variation with screenshots (although obviously the pixel dimensions do have to meet requirements) such as adding marketing text and images around a partial screenshot. You could maybe go that route if you can grab part of an iPad image.
Is your screen resolution too low on your Macbook or external monitor to take simulator shots of an iPad? If so, perhaps you can find a 4K/5K monitor to use temporarily (maybe even at a computer store by being nice to someone 🙂 ). Maybe landscape screenshots would work instead?
Anyways two ways you could grab them (with the Scale set to Pixel Accurate) are:
Hope that helps!