[Rd] image (PR#11493)

[Simon Urbanek]

Joseph,

please try a more recent R, I have addressed the issue in R-devel/ 
R-2.7-patched after your report.

Cheers,
Simon


On May 27, 2008, at 6:07 PM, Joseph Scandura wrote:

> 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
>>
>>
>