using rasterImage within image

On Feb 9, 2011, at 2:36 PM, Henrik Bengtsson wrote:

On Wed, Feb 9, 2011 at 11:25 AM, Simon Urbanek
<simon.urbanek at r-project.org> wrote:

Ben,

I have committed something analogous to R-devel (your rotation code was not unlike mine, I replicated the color handling from R internals to be consistent, I fixed the drawing limits and added a check for x/y conformance). Note that useRaster can only be used when x, y form a regular grid. Although I tried a lot of corner cases (requiring quite a few fixes), I'm sure I did not test all of them, so volunteers please give it a go and compare it with non-raster output.

The only thing I'm not quite happy about is the argument name: useRaster. Personally, I hate camel case in R (it has crept in more recently making it horribly inconsistent) so please feel free to suggest a better name ;).

It.is.spelled.camelCase.

Fortunately not in English ;)

What about style=c("image", "raster")? ?This allows for future extensions too.

Hmm.. it's not really a "style" - the output doesn't change (ideally) - it's more of a back-end specification .. also we already have oldstyle argument in image() adding to the confusion ...

Thanks,
Simon

Thanks,
Simon


On Feb 9, 2011, at 10:06 AM, Ben Bolker wrote:

On 11-02-08 10:03 PM, Simon Urbanek wrote:

Ben,

did you actually look at the result of your function with useRaster=TRUE ? ;) [Hint: don't use an image that is symmetric]

Apart from that nice bug there are more issues as well, try
image(matrix(1:4,2),col=1:3)
The underlying issue is that as.raster() is not quite what you would hope.
Unfortunately I'm not aware of an easy fix (that doesn't involve going

back to RGB decomposition).

In general, I think it's a nice option, but I don't think you'll get away with only a few lines...

Cheers,
Simon



On Feb 8, 2011, at 8:49 PM, Ben Bolker wrote:

Has anyone yet tried incorporating rasterImage into the base image()
function? ?It seems to make a *huge* difference, with
a very small number of added/changed lines of code. ?(Of course I have
barely tested it at all.)
Is there any reason this *shouldn't* go into the next release?

source("image.R")
z <- matrix(runif(1e6),nrow=1000)
image(z)
image(z,useRaster=TRUE)

(Patch against SVN 54284 attached; people can contact me if it doesn't
go through and they want it.)

Ben Bolker

<image_diff.txt>______________________________________________
R-devel at r-project.org mailing list

?Trying again. Rotated counterclockwise within R (although this *could*
be coded in C if speed were important?)
?Some brute-force testing suggests it is *slightly* slower for small
images (7 vs 8 seconds for 1000 reps) and still much faster (and
produces much smaller images, which don't suffer from antialiasing junk
in my PDF viewer) for large images.
<image_diff.txt><imagetest.R><image.R>