Create Slashed and dotted image through Rmagick in ROR

Hi friends ,
I have to create four type of images in my application (more like )
4. Gradient

I get succeed in order to create the gradient image through Rmagick
But i don't have any progress in rest of three .
Will anybody tell me how to create the above type of images through
Rmagick . If nayone having any idea please welcome.

Thanks In advance.