Downsizing technique

[chauncey]

I'm still pondering a Canon 5DsR, the 50 MP beast, in search of the ultimate IQ from the camera.

It is communally accepted that downsizing a high MP image to one of a lower one will produce a
better IQ than one would achieve by using a lower MP camera.

Question is, are you better off doing it in-camera as the Canon has the ability to drop down to a
1.3 or 1.6 crop in camera or, accomplish the whole thing in Photoshop by increasing the ppi?

BTW, what happens to noise levels with either technique?

[xpatUSA]

I'm still pondering a Canon 5DsR, the 50 MP beast, in search of the ultimate IQ from the camera.

It is communally accepted that downsizing a high MP image to one of a lower one will produce a
better IQ than one would achieve by using a lower MP camera.

Question is, are you better off doing it in-camera as the Canon has the ability to drop down to a
1.3 or 1.6 crop in camera or, accomplish the whole thing in Photoshop by increasing the ppi?

Changing the ppi does not change of size of the image.

BTW, what happens to noise levels with either technique?

For cropping, nothing. For down-sizing, noise is reduced proportionally by something like the square root of the reduction factor. Thus, downsizing to 1/2 gets you 1/1.414 of the noise. Obfuscation will set in as soon as anyone mentions gamma or your choice of down-sizing algorithm . . .

[george013]

I'm still pondering a Canon 5DsR, the 50 MP beast, in search of the ultimate IQ from the camera.

It is communally accepted that downsizing a high MP image to one of a lower one will produce a
better IQ than one would achieve by using a lower MP camera.

Question is, are you better off doing it in-camera as the Canon has the ability to drop down to a
1.3 or 1.6 crop in camera or, accomplish the whole thing in Photoshop by increasing the ppi?

BTW, what happens to noise levels with either technique?

I don't know if downsizing produces a better IQ. I don't believe that on the forehand.

To be sure I searched for what you meant with the crop factor. It's nothing more as using a part of the sensor. With exactly the same result as doing in PP. http://www.kenrockwell.com/canon/5ds.htm I'm sure it's also in the manual.

PPI is not a property of the image, more of the output device.

Since you just crop a part out of the sensor/image and the exposure doesn't change, the noise level will stay the same.

My thoughts.

George

[Manfred M]

The best possible image one can get is the "native resolution" of the image. The moment one either upsizes or downsizes, we get scenarios where the captured data is altered. When we downsize, we throw away data.

The reason some people seem to think the image "improves" is that we get what really amounts to "sharpening" in the image. The transition from light to dark areas become more apparent when the downsizing algorithms do their work. People often interpret this as a "better" image, but this is of course not true.

[Manfred M]

I don't know that much about the Sigmas, but as the original question dealt with the Canon Canon 5DsR. I'm not sure how relevant it is to this thread.

The internal processing of the cameras is going to vary a bit from model to model, but (in theory) the image that is interpolation free is going to give you the highest image quality.

[xpatUSA]

I don't know that much about the Sigmas, but as the original question dealt with the Canon Canon 5DsR. I'm not sure how relevant it is to this thread.

The internal processing of the cameras is going to vary a bit from model to model, but (in theory) the image that is interpolation free is going to give you the highest image quality.

It was posted for general interest to give a wider view of re-sampling, etc. I'll delete it for lack of relevance.

[ajohnw]

What comes out of a shot depends on the lens as well - and other factors. Downsizing can improve the results but as Manfred mentions when images are downsized they are generally sharpened. This is because downsizing will have an effect on detail. It doesn't generally loose it.

In terms of letting the camera do on jpg's I wouldn't however I have never tried downsized raw which some offer now.

John
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