Green Woodpecker

[kirisute]

I'm interested, thanks. It's a bit like anti-aliasing from my online gaming days whereby the PC graphics card fills in pixels with what it thinks should be there to smooth high resolution moving images.

 

From my basic back garden test it seems that in terms of detail captured my camera (a Nikon P7100) has similar crop/resizing capability to my PC, there's no real difference. I've yet to understand why the brightness is different, if digital zoom only crops & resizes the image captured at maximum optical zoom then the exposure shouldn't be affected?

Not quite " only crops and resizes". It actually uses a lot of algorithms to "guess" at pixels to produce a good image.

For instance imagine two pixels side by side, at 2dots per inch. On red, one dark red. In order to digitally scale them the camera would split them appart from two pixels per inch to four pixels per inch. In order to do that it must create two new pixels to fill the gap between the two old pixels it's now stretched appart.

The algorithms "guess" at pixel colour by looking at pixels either side and estimating the resulting new pixel.

So in the exemplar it would see red and dark red and hopefully create two pixels, red in colour between them...

This creates the larger image....how well the algorithms work decides how well the digital zoom works....but in practice it tends to darken images and blur them slightly.

A cropped and scaled image from original has a better chance of producing true colour than a digital zoom image due to better software and more power being thrown at it, plus photoshop etc can handle pixel scaling far better.