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I'm trying to increase the pixel density of an image so that when I shrink it, the image will keep the same resolution, except the pixels themselves are smaller.

Its current dimensions are 1024x512 and I'd like to scale it down to 64x32

And please don't blow up at me for those dimensions, and yes it's a Minecraft Skin.

I have access to Gimp and Inkscape on both a Windows 10 PC (Slower) and a Windows 7 PC (Faster).

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OK - no blowing up - but a simple basic comment:

If you downscale a raster graphic (made of pixels) this doesn't make the pixels smaller, this decreases the number of pixels you use in your raster to make up the graphic.

Hence your intended target size - 64x32 - is a per-edge-pixel-COUNT - as in, it will be 64 pixels wide by 32 pixels tall.

This means that you are going the other direction from your request - that is, the pixel-density (aka resolution) is going down as you scale your graphic, not up.

The use case in which shrinking an image down pushes up the pixel density is printing, in which yes, you can push the pixel density upwards to whatever the high end limit of the target printer is - often in excess of 300 DPI, some go well over 600 DPI.

If you scale your image in Photoshop, Gimp, Affinity Photo etc, but keeping in the same 72 PPI for-web file, you will see it resample the image once scaled and see the resolution drop drastically; similarly, if you export out from your native file as .png and force the export dimensions down to your target size, then open the resulting file in an image viewer or Gimp, you will see directly what happens: giant pixels relative to your image - you know - Minecraft style!

Maybe this will help this make more sense - I threw it together pretty quickly, but I think it should do:

Here's my image at original resolution (10x16 pixels) the red grid marks my pixels: enter image description here

I downscale the image to 5x4 pixels, and in this process the pixels remain the same size (cos that's what pixels do - they're always the same size on a given display) and the software analyzes groups of four pixels to determine the new pixel in that relative location - hence the loss of details and subtlety of colour treatments when you drop pixel counts.
enter image description here

Hopefully this helps you wrap your head around it a bit more.

Good luck.

  • Ok... what I wanted to know if it were possible to bump the pixel density back up to keep the same look like the original, just with fewer pixels. Still, you did an amazing job on the explanation, and I commend you for it. Thanks! EDIT: And to clarify: I know the pixel density will go down as I shrink the image, I just want to know if I can move it back to the same pixel density. – CStafford-14 Apr 16 at 22:05
  • @CStafford-14 - the reason this is hard to answer for you is that it makes no real sense. Imagine restating it with physical units: “I have made a piece of art with 36 apples, of many colours, in a 6 by 6 square, to photograph from directly above. If I consolidate my design down idea to a 3 by 3 square, can I somehow keep the detail in my original 36-apple arrangement in my 9-apple arrangement?” – GerardFalla Apr 18 at 15:19
  • @CStafford-14 one could say “yes” only if the design aligns perfectly with the lower number of apples, and if there was no small scale detail in the design. – GerardFalla Apr 18 at 15:21
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"Resolution" is a number of pixels per unit of length. A digital image has no physical dimension per se(*). The resolution is determined when that image is shown on a physical device, and cannot be better than the resolution of that device (100-300 pixels/inch for a screen).

When your image is shrunk to 64x32, whether it is done in ahead of time with Gimp or at run time by Minecraft it will lose **detail* because you cannot show the same thing in 2K pixels than in 512K. Doing it ahead of time save the disk space and probably also saves some CPU.

(*) what is the definition of photograph? is it the same for an insect or a mountain?

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