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when scaling between different formats is it width or height that counts???
I have a PP CS6 project that will demand mixing 4K, 1080P, 720P and 480i footage in a 720p timeline.
But I don’t know if it’s the width or the height that counts when scaling between formats.
And the scaling % changes when you’re dealing with formats that have different aspect ratios.
For example 4K (4096 x 2160) is a 1.9 aspect ratio whereas 1080p (1920 x 1080) is 1.78 aspect.To calculate the correct percentage when scaling down 4K to 1080P should I be looking at the width or the height?
1920 is 47% of 4096, but 1080 is 50% of 2160. So is it 47% or 50% that I should be scaling down to?
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2 Replies
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4K and 2K are optimized as digital cinema formats for different aspect ratios that either skirt max height or max width so delivering with shadow boxes or shadow columns are common. 1.9 as an aspect ratio is not a common cinematic ratio. Someone shooting full 4K or 2K should strongly consider using frame lines and safe areas.
What it comes down to is if you are converting aspect ratios. If you’re keeping 1.9 then you end up with shadow boxes. If you’re converting to 1.78 then you’ll crop the existing frame.
Either are acceptable unless you’re going to, say, TV where it would be unusual to see such slender shadowboxing. A full frame 1.78 crop would be preferred.
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1920 is 47% of 4096, but 1080 is 50% of 2160. So is it 47% or 50% that I should be scaling down to?
– Choose the larger percentage to fill the screen without black bars.
– Use the smaller percentage to maintain the entire clip with black bars.The best choice will depend on the source footage and the nature of the content. Unless there is vital information along both edges of the 4k footage, I recommend scaling at 50%.
If the 480 footage is not 16:9, the scaling factor will depend on image quality. Enlarging a high bitrate 720×480 anamorphic widescreen clip to 1280×720 will probably be OK, but upscaling compressed 640×480 footage by 200% might be too much.
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