Dear Thibaut, I am not sure what you want to do and what for you want to have a compressed version of an image in R. You can try the EBImage package, which is in the devel branch of bioconductor http://www.bioconductor.org/packages/bioc/1.8/html/EBImage.html It uses ImageMagick for image I/O and processing (so you need that, including header files and Magick++). It is still early in this package's life-cycle, so consider it an "alpha" version.
library(EBImage) y = read.image(system.file("data", "cat.jpg", package="rimage"), rgb=TRUE) object.size(y) [1] 702888 > dim(y) [1] 418 420 and this is 4 Bytes (a 32 bit int of which only the lower 24 bits are used) per Pixel, rather than 24 Bytes (3 doubles) in the case below. object.size(x) ## your example from rimage [1] 4214240 And there are some 2D filtering and image processing functions. Cheers Wolfgang ------------------------------------- Wolfgang Huber European Bioinformatics Institute European Molecular Biology Laboratory Cambridge CB10 1SD England Phone: +44 1223 494642 Fax: +44 1223 494486 Http: www.ebi.ac.uk/huber ------------------------------------- Thibaut Jombart wrote: > Hello list, > > here is a question relative to pixmap pictures in R. Manipulating such > objects is quite demanding for the RAM, as large matrices are created. > > For instance, try to execute the example of rimage library : > > ### R code ### > library(rimage) > x <- read.jpeg(system.file("data", "cat.jpg", package="rimage")) > plot(x) > object.size(x) > save.image() > ### end of R code ### > > Moreover, the '.RData' will be approximately the size of 'x' (around 4 > MB), despite the jpeg size is only 16 KB. > Of course it is possible store only the expression reading the pictures > instead. > For instance: > > ### R code ### > y=expression(read.jpeg(system.file("data", "cat.jpg", package="rimage"))) > object.size(y) > object.size(eval(y)) > plot(eval(y)) > ### end of R code ### > > But... does anybody know if compressed pictures could be stored in R? > And if yes, how ? > > Thanks, > > Thibaut. ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel