Round edges of pixel-art ?

Hello !
I am struggling to find a way to make a pixel grass billboard have round edges.
You can see the grass billboards style I want here : http://img4.wikia.nocookie.net/__cb20140611075434/unturned-bunker/images/5/52/Grass_sniffer.png it's from unturned.
I would really want to do something like this.
What I tried : Do a pixel art grass on low resolution image then change the resolution to a high value without anti-aliasing.
The only thing I need is a filter, a blur or something which blurs the edges without anti-aliasing in order to have only one color.
I am using Gimp 2.8 but I also have Photoshop sc 2, yeah that's old but free. Sure.

Your help would be very appreciated.

 

Try Cutout shader, with the texture as bilinear (not point)

 

Is this a tool in Unity or Gimp ?
I would prefer something with the picture itself than doing something upon it in unity.
I need my game to be very optimized.
Thank you .

 

In unity,
it then looks like this:
http://unitycoder.com/blog/wp-content/uploads/2015/03/pixel_rounded_edges_shader.jpg

 

I tried but I am a bit confused.
Where am I supposed to find the menu at the bottom right ?
I set the image to Sprite then ... ?

 

Which unity version you are using? (that screenshot is from 5.0)
Or are you going to use it on terrain, as sprites or ..?

in 4.x
Create new material,
assign grass texture
assign "shader: Transparent/Cutout/Diffuse" (or others from cutout/)

 

Unity 5.0 :
I want to use a normal 2D texture as a terrain's billboard grass texture.
So, does your cutout technique work with my situation ?
Because from what I could see, you can't use a material as a 2D texture for a grass billboard on a terrain.
Thank you.

 

At least it looks similar (without any custom materials or shaders):
- Select terrain
- Paint details tab
- Edit details
- Add grass texture
- Assign texture2D, Add
- Paint to terrain

 

But the issue is that by doing that my texture is the same as I started. I know how to add a billboard on a terrain, I just was asking for the filter or a technique to get the result I want (here ).
I can't apply a cutout filter on that Grass Texture once I have added it or even before without making it a material, plus I think the only way to use the cutout is by making a material out of the texture.
I am sorry if I am bothering you so much, I am very confused because I yet have no experience in this subject.
I really appreciate your help and the fact that you take your time to explain me

 

It looks like this for me on terrain:

 

Wait, I am wrong then.
What you did is :
Take a texture, make it bilinear and cutout, to do cutout you have to make a material from it.
Then you put the material as a 2D texture in the terrain.

 

Actually didnt do anything
- Added texture to project (attached the sample image)
- Painted it to terrain

 

Yeah lol, I was so confused, anyways thank you very much.
Kiwi

 

I'd be really interested in a shader that rounds the edges but not what's inside.