[R-SIG-Mac] add a bitmap graphic onto a plot

[Simon Urbanek]

On Jun 5, 2008, at 7:36 AM, Denis Chabot wrote:

> Hi,
>
> a bit frivolous, I know, but I thought of adding a small picture of  
> each species of fish onto the upper right corner of plots dealing  
> with metabolic rate of several species of fish.
>
> The only information I could find about doing this involved a  
> package named pixmap. But from what I understand, I must first make  
> the picture of each fish (diverse original formats, gif, jpeg, pdf)  
> into a pnm format.
>
> How do I manage this on Mac OS X? I had never come across this  
> format before.
>

IMHO the simplest solution is to save your image(s) into uncompressed  
TIFFs (e.g. open the image in Preview and Save As.. , Format: TIFF ,  
Compression: None). The you can use this simple function to read TIFFs  
into pixmaps:

read.tiff = function(con, ...) {
     if (is.character(con)) {
         con = file(con, "rb")
         on.exit(close(con))
     }
   sig = readBin(con, 1L, 1, 2)
   if (sig != 0x4949 && sig != 0x4d4d) stop("Invalid signature")
   end = if (sig == 0x4949) "little" else "big"
   if (readBin(con, 1L, 1, 2, endian=end) != 42) stop("Invalid  
signature")
   o = readBin(con, 1L, 1, 4, endian=end)
   data = readBin(con, 1L, o - 8, 1, signed=FALSE, endian=end)
   ifds = readBin(con, 1L, 1, 2, endian=end)
   info = list()
   for (i in 1:ifds) {
     tag = readBin(con, 1L, 6, 2, endian=end)
     if (tag[1] == 257) info$height = tag[5]
     if (tag[1] == 256) info$width = tag[5]
     if (tag[1] == 259 && tag[5] != 1) stop("compressed TIFFs are not  
supported")
   }
   if (is.null(info$width)||is.null(info$height)) stop("missing width/ 
height tags")
   res = array(data/255, dim=c(3, info$width, info$height))
   z = pixmapRGB(0, ncol = dim(res)[2], nrow = dim(res)[3], ...)
   z at red = t(res[1, , ])
   z at green = t(res[2, , ])
   z at blue = t(res[3, , ])
   z
}

Cheers,
Simon


> I have seen another way using grImport to import postscript vector  
> graphics. Does anyone here know if this will also work if I  
> transform my original pictures and drawings into postscript format  
> (which obvisouly won't be vector based)?
>
> Thanks,
>
> Denis Chabot
>
> _______________________________________________
> R-SIG-Mac mailing list
> R-SIG-Mac at stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>
>