image (PR#11493)

Sorry for lack of clarity in my original message but I'm new to this  
list and I couldn't find away to upload images.

I am running Mac OS 10.5.2, R 2.7.0
The problem arrises when using anything that depends upon image()  
using the Quartz() device. This sounds very much like what you are  
describing with the background showing through (most obvious with  
tiny boxes in the example, n=100000). The problem does not occur  
when I use an x11 device. It sounds like this is an old problem  
without a good solution. What puzzles me is that I did not have the  
problem using quartz as a screen device prior to upgrading to 2.7.0.

Do you know of a workaround? I have tried setting  
quartz(antialias=F) but still have the problem.

tempF<-function(n) {
im<- matrix(0,nrow=n,ncol=5)
for (i in 1:5) {
 im[,i] <- seq(1,n)
}

image(im , col = topo.colors(100))
}

tempF(10)
tempF(1000)
tempF(100000)


<Summary.001.png>

On May 21, 2008, at 10:22 AM, Simon Urbanek wrote:

On May 20, 2008, at 8:05 PM, jms2003 at med.cornell.edu wrote:

Full_Name: Joseph Scandura
Version: 2.7.0
OS: Mac 10.5
Submission from: (NULL) (140.251.50.94)


Since updating to 2.7.0 all plots that use image() (heatmap,  
etc...) now draw
visible boxes around each rectangle in the plot. When there are  
many rectangles
the surrounding color becomes dominant over the rectangle color  
and the overall
image is borderline useless.

Can you, please, specify exactly which graphics device you are  
using and possibly a snapshot of the problem? I don't see any  
additional boxes being drawn on any device.

The only issue I'm aware of are anti-aliasing effects around the  
edges of adjacent rectangles which don't fall on the pixel boundary  
(if anti-aliasing device is used). Depending on the subpixel  
location of the edge, the background color may shine through very  
slightly. It's not what you describe, but it's closest to what I  
can imagine you could mean. However, AFAICS this has not been  
changed recently and is a rendering artifact which is hard to get  
rid of in the current setup as devices are resolution-independent  
(the only cure I'm aware of [short of disabling anti-aliasing]  is  
to distort the original plot such that rectangles are aligned with  
the pixels of the output medium).

Cheers,
Simon