Zooming Again

The whole idea of digital zooming has been suspect from the word go. As you effectively crop an image (which is what you are doing when you digitally zoom) you are left with only a tiny fraction of your original pixels. This means that the final image undergoes a drastic loss of both size and density. 

Thus the conventional advice suggests zooming the image in post processing using software which interpolates pixels as you go. Interpolation involves creating more pixels to slip between the existing ones to fill up the zoomed image, replenishing size and apparent density.

I have researched my new smart phone. When it digitally zooms, at the point of image capture, it purports to increase the number of original pixels by a factor of four, such that if an image is effectively cropped to (say) 25% of the original composition at the point of capture, one is left with the same number of pixels that one began with, theoretically retaining the original image's density and size. This is why (apparently) the sensor is described as 48mp while only actually delivering manageable 12mp files.

If this is actually what happens, then a picture shot using digital zoom SHOULD in fact look better than one blown up by interpolation in PP. 

Now the other day I shot a picture of a yellow cleaner's sign using 8x digital zooming which looked pretty muzzy. I worried that the real reason this occurred was because I hadn't held the phone steadily enough. So I did the exercise again. This time I secured the phone by jury rig to a tripod.

The LEFT most image (above) shows the unzoomed image of an unpainted timber indoor plant pedestal in my living room. The CENTRE image shows a cropped section of the image blown up by interpolation in PP software. The RIGHT most image is a completely different exposure, shot while using 8x digital zooming.

No sharpening was applied at any time. No changes were made to colour, brightness or contrast. What you see is what I got. I must admit that I cannot explain why the colour is different between the centre and right images. More experimentation needed. In any case PLEASE VIEW IN LARGE.