ImageMagick: Zoom an image by integral zoom factor without any smoothing?

Question

I have a 256×256 PNG image in a.png that just consists of black and white pixels.

What I want is just to zoom it by a factor of 4, so that each pixel becomes a 4×4 block of the same color. So what I did is:

> convert a.png -geometry 1024x1024 a4.png

The problem is that the resulting image a4.png is blurred and is no more 2-colored black-and-white.

What does not work:

With -colors 2 I am getting an output with only 2 colors, but they are grey-ish, not black + white. And the image looks dithered even with -dither none.
-dither none has no effect.
-quantize-colorspace has no effect.
-solarize 128 has no effect either.
-depth 1 does not work (shreds the image).

Thanks in advance for any hints.

score 2 · Accepted Answer · answered Feb 03 '23 at 20:57

2

Try:

convert input.png -scale 1024x1024 result.png

answered Feb 03 '23 at 20:57

Mark Setchell

1

Or if he wants it scaled 4x, then `convert input.png -scale 400x400% result.png` – fmw42 Feb 03 '23 at 21:48

1 Answers1