windowed vs scaled?

[tom lombard]

I could use a bit of education on the differences between "windowed" and "scaled".  For example, shooting at a higher frame rate at 1080 being either scaled from 2k or windowed.  Scaled is full sensor image just reduced in size (and quality)?  Windowed is smaller, center portion of the sensor (but original quality)?  Am I close?  Specific to BM P4K FWIW.  Thanks, Tom

[David Mullen ASC]

Not quite right about "original quality" -- ideally your camera would properly scale down a large pixel image into smaller sizes for recording in smaller-sized formats so that the entire sensor is used for the image (give or take depending on your aspect ratio) and you get the benefits of oversampling.

Some cameras use other methods to retain the whole view of the sensor like pixel binning and line skipping to knock down the resolution but this leads to artifacts like aliasing.

Other cameras simply crop the sensor area to the smaller pixel dimensions but then you lose the field of view of the larger sensor area and the image can look noisier and fuzzier simply from using fewer pixels. But it also depends on the particular camera and the degree to which you are cropping.

Generally rescaling looks better due to oversampling to get the smaller size file but it depends, a tiny amount of rescaling can be worse than cropping a tiny amount. For example, if you want to end up with a UHD file (3840 x 2160), ARRI recommends recording 3.2K rather than the max 3.4K on the Alexa because the rescaling math is better when you go from 3.2 to 3.8 than from 3.4 to 3.8.

[Phil Connolly]

On the pocket 4k. I believe scaled full sensor is limited at 60 fps and the cropped windowed mode allows 120 fps. 

In 1080p mode scaled looks better but windowed looks good too. It's a tight crop though, difficult to shoot wides

[tom lombard]

thanks for the input.  i've been wanting to narrow down my options and settle on something consistent so that i can focus on other aspects of filmmaking rather than thinking about different codecs & such.  for now, i'm going with ProRes 422 1080p and scaling if i need higher frame rate.   will kick it up to ProRes 4K when i need better quality.