image size (drawable-hdpi/ldpi/mdpi/xhdpi)

Hope this will help...

mdpi is the reference density -- that is, 1 px on an mdpi display is equal to 1 dip. The ratio for asset scaling is:

ldpi | mdpi | hdpi | xhdpi | xxhdpi | xxxhdpi
0.75 | 1    | 1.5  | 2     | 3      | 4

Although you don't really need to worry about tvdpi unless you're developing specifically for Google TV or the original Nexus 7 -- but even Google recommends simply using hdpi assets. You probably don't need to worry about xxhdpi either (although it never hurts, and at least the launcher icon should be provided at xxhdpi), and xxxhdpi is just a constant in the source code right now (no devices use it, nor do I expect any to for a while, if ever), so it's safe to ignore as well.

What this means is if you're doing a 48dip image and plan to support up to xhdpi resolution, you should start with a 96px image (144px if you want native assets for xxhdpi) and make the following images for the densities:

ldpi    | mdpi    | hdpi    | xhdpi     | xxhdpi    | xxxhdpi
36 x 36 | 48 x 48 | 72 x 72 | 96 x 96   | 144 x 144 | 192 x 192

And these should display at roughly the same size on any device, provided you've placed these in density-specific folders (e.g. drawable-xhdpi, drawable-hdpi, etc.)

For reference, the pixel densities for these are:

ldpi  | mdpi  | hdpi  | xhdpi  | xxhdpi  | xxxhdpi
120   | 160   | 240   | 320    | 480     | 640

MDPI - 32px
HDPI - 48px
XHDPI- 64px

This Cheat Sheet might be handy for you. check the image :-)

https://i.stack.imgur.com/kV4Oh.png

I have a full explanation already posted here

Basically, General guidelines for designing images are:

ldpi is 0.75x dimensions of mdpi
hdpi is 1.5x dimensions of mdpi
xhdpi is 2x dimensinons of mdpi

Usually, I design mdpi images for a 320x480 screen and then multiply the dimensions as per the above rules to get images for other resolutions.

Please refer to the full explanation for a more detailed answer.

See the image for reference :- (Soruce :- Android Studio-Image Assets option and Android Office Site )

https://i.stack.imgur.com/dagIk.png

Tablets supports tvdpi and for that scaling factor is 1.33 times dimensions of medium dpi

    ldpi | mdpi | tvdpi | hdpi | xhdpi | xxhdpi | xxxhdpi
    0.75 | 1    | 1.33  | 1.5  | 2     | 3      | 4

This means that if you generate a 400x400 image for xxxhdpi devices, you should generate the same resource in 300x300 for xxhdpi, 200x200 for xhdpi, 133x133 for tvdpi, 150x150 for hdpi, 100x100 for mdpi, and 75x75 for ldpi devices

low dpi is 0.75x dimensions of medium dpi high dpi is 1.5x dimensions of medium dpi extra high dpi is 2x dimensinons of medium dpi

It's a good practice to make all the images in vector based format so you can resize them easily using a vector design software like Illustrator etc..

As of Octoer 2020, the dimensions for Launcher, ActionBar/Tab and Notification icons are:

https://i.stack.imgur.com/5MrnU.png

A very good online tool to generate launcher icons : https://romannurik.github.io/AndroidAssetStudio/icons-launcher.html

you can use Android Asset in android studio , and android Asset will give you image in this size as a drawable and the application will automatically use the size based on screen of device or emulate

Not just tab icons, notification and launcher lives an app. I was confused about the sizes of the other icons used for different situations in the app.

I'm using 32px mdpi (Action Bar icons) dimensions and I cannot say if it would be correct.

https://i.stack.imgur.com/0U8i6.png