Information processing system. controller, and control method for diffusion of a quantization error

A controller that drives pixels arranged on an electrophoretic display panel based on a quantized value indicating gradation for each of the pixels,

• the controller being configured to
• quantize a gradation value of each pixel included in a dynamic region of each element of a display image notified by a host system at a bit depth lower than a bit depth of a pixel included in a non-dynamic region to compute the quantized value,
• diffuse a quantization error of each pixel to other pixels arranged within a predetermined range from the pixel in the dynamic region of the element and update the quantized value of the other pixels,
• diffuse, with a spatially discontinuous distribution, the quantization error of pixels arranged at an edge of the dynamic region and update the quantized value of the pixels arranged at the edge, and
• not diffuse the quantization error of the pixel outside the edge.

A control method for an information processing system including a host system and a display unit, wherein the display unit includes a controller and an electrophoretic display panel, and the controller is configured to drive pixels arranged on the electrophoretic display panel based on a quantized value indicating gradation for each of the pixels, the control method comprising:

• via the host system,
• detecting an edge from a display image, and
• determining a region that is surrounded by the edge and in which display content dynamically fluctuates for each element as the dynamic region, and
• via the controller,
• quantizing a gradation value of each pixel included in the dynamic region at a bit depth lower than a bit depth of a pixel included in a non-dynamic region to compute the quantized value,
• quantizing the gradation value of each pixel included in the dynamic region with 1 bit to compute the quantized value,
• diffusing a quantization error of each pixel to other pixels arranged within a predetermined range from the pixel in the dynamic region of the element and updating the quantized value of the other pixels,
• diffusing, with a spatially discontinuous distribution, the quantization error of pixels arranged at the edge and updating the quantized value of the pixels arranged at the edge, and
• not diffusing the quantization error outside the edge.