Icon resolutions: Pixels vs DPI

3
votes

When I try to do some research on making icons for Windows, and what size/resolution images I should leave in my .ico files before saving, there's too much weird information.

Some say put 16x16, 24x24, 32x32, 48x48 ... and so on in 96 DPI.

This is what irks me, and I feel it doesn't make any sense.

Isn't 1 pixel = 1 pixel?

Why do they insist on mixing DPI into this?

1
windowsiconspixelresolutiondpi
DPI is a rough measure for how big the pixel is on the user's screen. And if he bought a nice expensive "retina" display then your pretty 48x48 icon turns into but a fleck of dust. You don't have to fix it, Windows will rescale the icon to keep it useful. But of course that doesn't look as good as an unscaled 256x256 icon. There's usually limited wisdom in disappointing users that are willing to spend money. – Hans Passant
Thanks for the input. Sorry for the ambigous question, but to clarify: I did say " ... and so on", that means all the way up to 256 which is the max recommended on Windows 7... What I wondered was WHY they say something like "Make the icon x pixels wide and x pixels high in x DPI". I thought one pixel was one pixel no matter what, but this made me wonder... – svin83

1 Answers

2
votes

What is always true is that 1 pixel = 1 pixel. What does change is how big that pixel is one various displays that have different screen densities. That is what DPI describes - number of dots (pixels) per inch. But using DPI in context of image size only makes sense when you use it in combination with inches (centimeters). For instance "create image 10x10 inches at 300 DPI" and from that statement you can calculate that image has to be 3000x3000 pixels in size.

As far as Windows is concerned what does count is font scaling setting that can be set from 100% to 200%

So when you are creating your icons make sure that you have at least 1x and 2x dimensions. If the icon has to be 16x16 pix under normal resolution, that means that you would also create 32x32 pix icon. Other commonly used scaling are 125% and 150%, so it would be good idea to provide icon for those sizes too.

You can freely ignore statements like "Make the icon x pixels wide and x pixels high in x DPI" because those people have no clue what they are talking about.