Android的Icons DPI

Question

I apologize for the simple question, but I am a bit confused.

I am creating my first Android app. Functinally I am done. I am now working on the UI. According to this , I am required to provide multiple icons to support different screens and I understand this part.

So I created a vector image, and was about to export it to generate a number of icons to support multiple resolutions. However, I could not find the require DPI. According to this , I am supposed to support different DPIs, but the article does not explain how to do that.

Can you please advise me on how to select the proper DPI? Does it even matter? I thought it does, but maybe my understanding is wrong.

Thanks.

EDIT:

Just to clarify my question. When I am exporting an image from a vector to a raster image, I have to select its dimension (so in my case, 400px X 200px), and its dpi. So what should I choose for DPI? Is that the same DPI that will create different icon sizes? I am confused. Thanks again.

Answer 1

For what concerns dpi , I use to follow the screen dpi:

640 dpi for xxxhdpi screens
480 dpi for xxhdpi screens
320 dpi for xhdpi screens
240 dpi for hdpi screens
160 dpi for mdpi screens
120 dpi for ldpi screens

This way I'm sure the icons are appropriate to the screen resolution.

I'm also sure that I can skip some (if not all) the lower qualities, once I have the highest resolution graphics, because they will scale down nearly perfectly.

But, since I'm a perfectionist, nearly disturbs me.
So, I do provide all the resolutions graphics.

---

For what concerns dimensions use this cheatsheet: http://petrnohejl.github.io/Android-Cheatsheet-For-Graphic-Designers/#dimensions

---

You can make this experiment:
for an xhdpi screen, prepare a 800px X 400px image at 72 dpi ( and no other images for other resolutions ) and see how does it scale down in a lower resolution physical device, say an ldpi screen (it will look really bad )...
Then prepare a 800px X 400px image at 480 dpi ( and no other images for other resolutions ) and, after scaling (will look very good , on the same ldpi screen), compare the result to the previous one.

The difference will be evident on a physical device, much less on an emulator.

It's a way of doing things when you want to save some bytes on lower resolution pictures: just prepare the highest resolutions ones and let Android scale them down (it will scale down the ones it doesn't find in their folders).

Answer 2

I am writing my conclusion for the greater good. After further reading and investigation. It appears that DPI is not important when I am creating an image for a screen. So when I choose 400px X 200px, and assuming this will be for mdpi, then I should choose 800px X 400px for xdpi (and so on and so forth). The dpi should be ignored in all cases (does not matter if I chloose dpi of 90 or 600, as long as this is not for printing). On the other hand, if I am to print the image, then dpi is important.

---

EDIT

This is a great article about the topic. Please read it, it explains things very well.