Image pixels: full, medium, small

[daveleo]

I have a question that I knew the answer to at one time, but need confirmation.

Consider a camera with an APS sensor, 16Mp.
Set it at "full resolution" or "large picture size" and you get a 4899X3266 image, using the full sensor area.
Set it at "medium" or "small" resolution and you get an image with less pixels.

Since the lens always produces the same image circle and that is at least as large as the sensor, it must be that the reduction to "medium" and "small" is a camera algorythm. This would be the same concept as "scaling down" a full size the image on your compter.

Specifically, the medium and small resolution images do NOT occupy less sensor area. They are reduced after the picture is recorded. Same as your computer.

Correct?

 

[ruby.monkey]

Yes and no. If you're shooting in a cropped mode then you're capturing a smaller area of the sensor (though it may well be that the cropping occurs after capture, rather than by ignoring the outer sensors at the time of capture). If you're shooting the full frame size at a lower resolution then the camera is down-sampling the image after capture.

 

[lonemantis]

Can an APS sensor have an extra cropped mode?

It's entirely possible. My Olympus E-M5 has a "digital teleconverter" function, which enlarges the image 2x with half the resolution. This essentially takes the central portion of the already 2x crop sensor, leading to 4x total crop. (vs 35mm full frame)

 

[daveleo]

Thanks for the replies.
I had been a bit off balanced by a comment in another forum, which is why I asked.