(This article was first published on Quantitative Ecology, and kindly contributed to R-bloggers)
This is how to use the Pixmap library to read in an image as a matrix.
> library(pixmap)
# the next command may only work on Linux
> system("convert foo.tiff foo.ppm")
> img <- read.pnm("foo.ppm")
To get info on your new object:
> str(img)
Although included in the previous output, the size of the image can be extracted by:
>img@size
Then to extract the red channel from the image for the first ten rows:
> myextract <- img@red[1:10,]
Or to extract the entire red channel to an actual matrix:
> red.mat<-matrix(NA,img@size[1],img@size[2])
> red.mat<-img@red
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