When using a retina/hidpi version of a PGraphics (or PImage, for that matter), all pixel operations happen in 2x space. This has an effect on:

• updatePixels(...)
• get(...)
• set(...)
• copy(...)
• blend(...)

The pixelFactor variable is 2 for retina, 1 normally. The pixelWidth and pixelHeight fields cover the actual size of the pixels[] array.