2D plots with filled in pixels should put tick marks at center of pixels

[DanielSank]

Right now, the tick marks are on boundaries between pixels. This makes it annoying to pick out the numerical value of a pixel in the 2D plot.

[maffoo]

Pixels are not necessarily all the same size; how would you propose to handle that?

[maffoo]

That is, data may be taken on a non-uniform grid.

[DanielSank]

I don't understand this question because I don't understand how drawing the ticks in the wrong place as we are now is more correct for ragged data.