[Rd] image (PR#11493)

[Joseph Scandura]

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)


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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
>
>