Scaling ratio in Android images?

Question

I am developing a simple informative system which will use a lot of images. The problem is I do not know how to scale them to the folder of ldpi, mdpi, hdpi, and hdpi.

I read that android uses a scaling ratio like 3:4:6:8. Can some explain to me what is this 3:4:6:8 scaling ratio? How do I use it, and what is the logic behind it?

Suppose I have a 50x50 px image in ldpi folder. If I am going to use 3:4:6:8 ratio. What will be the next image size for my mdpi folder and hdpi folder?

Please help. I dont realy understand that scaling ratio. Sorry for this, I'm only a newbie in android design.

Answer 1

Mostly they use these standard sizes:

ldpi: 36*36 mdpi: 48*48 hdpi: 72*72 xhdpi: 96*96

Answer 2

Its so simple.

If image size is 50*50 for Ldpi then:

MDPI => 67*67

HDPI => 100*100

XHDPI => 125*125