Normalmap from Grayscale changes Sizes

Hi,

I'm working on a 2D game and i made a Shader that uses Normalmaps on Sprites. now when i draw a heightmap for my sprite and und mark it as a Normalmap and check the box for "Create from grayscale" it generates the right normalmap, but in the wrong size.

for example:
i have a Sprite 10x10 Pixel,
i have a heightmap 10x10 Pixel,
if i now generate a Normalmap from that the normalmap is 8x8 pixel.

okay when thinking about normalmaps and what they realy are its right, i have 10 pixel so there are 8 gradients between.

but now comes my problem:
when i make a heigtmap of 12x12 pixels to get the 10 gradients inbetween unity produces a normalmap with 16x16 pixel from that.

is there anyone who can explane to me why this is happening and/or can tell me how to change that?

 

It happens because your textures are NPOT. (Not Power Of Two.)

Older desktop GPU's and current mobile GPU's only support textures with a width and height that equals 2, 4, 8, 16, 32, etc. I'd say that would pretty much be on the first page in a book on computer graphics.