Image visualization: should first pixel be centered at (0,0)

[PierreRaybaut]

In camera imaging software, pixels are always centered at their position. For example, the first image pixel (top-left corner) is centered at (0,0). In guiqwt, this pixel is not centered at (0,0): the top-left corner of this pixel is at (0,0).

[ldo]

Pixels don’t have “corners”. Pixels are not little squares. In ideal sampling, pixels are points.

[PierreRaybaut]

But pixels are not in indivisible in image processing. So this is about how we handle subpixels, for example when zooming in (or when handling images with binning other than 1x1).

So, pixels do have corners, from a certain point of view (with the necessary language précautions).

[ldo]

Resampling a set of pixels produces another set of pixels. The original samples are points, the new ones are points, too.

[PierreRaybaut]

Yes but as long as there will be subpixel measurements, there will be people that ask me where is the pixel origin, formerly either at its center or at its top left corner (the latter being a non intuitive answer, unfortunately for me: because it would require some work to properly implement this in guiqwt). And I can't simply answer them a Jedi-style "there is no corner, there is no center, there's only a pixel" 😁.

[ldo]

It doesn’t have to be Jedi Zen-style; just point them at Alvy Ray Smith if they want more of an answer. He knows more about it than you or I.