[R] Remove "gray grid" from levelplot

[Martin Sandiford]

On 06/03/2006, at 10:40 PM, Prof Brian Ripley wrote:

> On Mon, 6 Mar 2006, Martin Sandiford wrote:
>
> [...]
>
>> P.S. To me, the png() device does not appear to do sub-pixel
>> rendering.  The postscript() and pdf() devices do.
>
> What could you possibly mean by that?
>
> The postscript() and pdf() produce vector graphics and have no concept 
> of a pixel.  There are filled polygons as part of the language they 
> output. (Of course the coordinates are output to finite resolution, in 
> fact 0.01dp = 1/7200", so you could think of that as the positioning 
> quantum.)
>
> The png device writes on a bitmap.  It outputs a rectangular grid of 
> either pre-defined colour indices or RGB values.  There is nothing in 
> the PNG standard to allow anything finer.

Sorry, sloppy and inaccurate description.  The Mac Preview app 
antialiases based on the translated fractional device coordinates when 
viewing PDF/PS files.

I don't believe the png device does antialiasing directly.

Martin