Method and apparatus for improving the image quality of variable rate shading using gradients

A method to post-process variable pixel rate output using gradients in a Graphics Processing Unit (GPU), the method comprising:

• determining, by the GPU, that variable rate shading is enabled for a draw call of an application;
• determining, by the GPU, that gradient processing is enabled for variable rate shading;
• determining, by the GPU, a block of pixels that corresponds to a predetermined kernel size in the draw call;
• instantiating, by the GPU, a pixel shader run to generate pixel shading values for at least two pixels located within the block of pixels;
• and
• generating, by the GPU, a gradient output for the block of pixels based, at least in part, on an interpolation of the pixel shading values for the at least two pixels over the block of pixels, wherein the predetermined kernel size and a location of the two pixels located within the block of pixels are based on a variable rate shading rate profile.

A graphics processing unit (GPU), comprising:

• a graphics pipeline configured to increase a pixel rate of rendered content;
• and
• a controller coupled to the graphics pipeline, the controller being configured to:
• detect a block of pixels that corresponds to a predetermined kernel size for variable rate shading in a draw call of an application,
• instantiate a pixel shader run to generate pixel shading values for at least two pixels located within the block of pixels, and
• generate a gradient output for the block of pixels based, at least in part, on an interpolation of the pixel shading values for the at least two pixels over the block of pixels, wherein the predetermined kernel size and a location of the two pixels located within the block of pixels are based on a variable rate shading rate profile.