Dichromacy isn't exactly a unique mammalian condition

What is this?

A Javascript tool for plotting a circle on a square grid.

Just enter the radius or diameter. Decimals allowed.

Typically even diameters should have "centre on cell" enabled and odd diameters have it disabled, such that the red circle runs through the centre of the grid cells.

Your browser doesn't support canvases. I can't help you, sorry :(