Joris, On Feb 14, 2011, at 10:05 AM, Joris Meys wrote:
> Dear all, > > I noticed in the latest R version (R.2.12.1) that the readPNG gives > following warning when running the example code in the help file (or > when using any other png for that matter) : > > 50: In rasterImage(img, 1.2, 1.27, 1.8, 1.73) : > Per-pixel alpha not supported on this device > > No picture is shown, and code I used to be able to run, doesn't run any more. > You may want to use a device that supports alpha. The R logo in the example uses alpha so are probably the images you are using. If you don't want to (or can't) use a device that supports alpha, you'll have to flatten the alpha, - i.e. plot just img[,,1:3] However, most images don't have color where alpha is zero, so you'll have to replace it with the background color, e.g.: r = as.raster(img[,,1:3]) r[img[,,4] == 0] = "white" Cheers, Simon >> sessionInfo() > R version 2.12.1 (2010-12-16) > Platform: i386-pc-mingw32/i386 (32-bit) > > locale: > [1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United > States.1252 LC_MONETARY=English_United States.1252 > [4] LC_NUMERIC=C LC_TIME=English_United > States.1252 > > attached base packages: > [1] grDevices datasets splines graphics stats tcltk utils > methods base > > other attached packages: > [1] png_0.1-2 svSocket_0.9-51 TinnR_1.0.3 R2HTML_2.2 > Hmisc_3.8-3 survival_2.36-2 > > loaded via a namespace (and not attached): > [1] cluster_1.13.2 grid_2.12.1 lattice_0.19-13 svMisc_0.9-61 > tools_2.12.1 > > > -- > Joris Meys > Statistical consultant > > Ghent University > Faculty of Bioscience Engineering > Department of Applied mathematics, biometrics and process control > > tel : +32 9 264 59 87 > joris.m...@ugent.be > ------------------------------- > Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php > > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
