Crop/digital zoom quality

Started 11 months ago | Discussions thread
tedolf Forum Pro • Posts: 26,896
Would be true if....

Ionion wrote:


I have an 1080p monitor, which is around 2MP. So, in theory I should be able to crop any 2MP region out of a higher megapixel count camera and the quality should be good.

That would be true if you were working with a non -compressed file such as a TIFF file.

But in practice that doesn't happen. 2MP regions out of my 12MP phone camera look horrible in both jpeg and raw,

You are probably not really displaying a RAW file from your cell phone.  By the time you get it to your desk top it is probably in a compressed form.

and with high end DSLRs the situation is a bit better, but I still can't crop a good looking image in jpeg/raw even from a $5000 DSLR.

Are you sure that you are displaying the RAW file?

That applies to digital zoom as well. With 12MP on my phone camera (S7) and a 3.6MP display, I should be able to do a X3 digital zoom without visible quality loss on that display, and this is not the case.

Why does that happen ? How can they advertise a given megapixel count if I can't use a 2MP crop on a 2MP display ?

The only answer I can think of is that the image quality pixel by pixel is quite noisy everywhere, but the algorithm that downscales the resolution for lower MP displays takes the average out of a given pixel region and the noise is reduced this way.

Are you really looking at the RAW file, or a TIFF file?

Am I correct on this ? What parameter of the camera is that dependent on ? How do I choose a camera that has good crop/digital zoom capabilities ?

Thank you


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