: Calculating dots per pixel when printing an image There is a nice article I found explaining dots, pixels, ppi, dpi etc. Here it is. Very good overall, but I got confused at one point where

@Nimeshi706

From the article:


For example, if you are printing a 150ppi image at 600dpi, each “pixel” will consist of 16 dots (600 dots/150 “pixels” = 4 rows of 4 dots per “pixel”).


600 divided by 150 is 4, so the numbers make perfect sense.


From what I gather it should have been 4 dots / pixel. Why "4 rows of 4 dots per pixel".


What you have to remember is that the numbers work in both dimensions. So there is 4 dots per pixel, but in each dimension, so you actually have (4 × 4) 16 dots. To get 4 dots per pixel the image would need to be half the resolution.

To illustrate the point, take the following simple image, increased (and resampled) from 150 PPI to 600 PPI. You can clearly see each "pixel" is made up of 16 (4 × 4) pixels:



The article is massively over simplifying things though as that's generally not how printing works. A printed dot does not align with the pixels in an image. But as an over-simplification for illustrative purposes, the statement makes sense.

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