[R] Using an image background with graphics
Waichler, Scott R
Scott.Waichler at pnl.gov
Tue Oct 21 07:12:27 CEST 2008
> The rimage package has functions for reading in and plotting
> jpeg files that you could use for displaying the photograph.
> If you then can find 2 points in the image (not on the same
> horizontal or vertical line) for which you know the
> coordinates in the coordinate system that you want to plot
> in, then you can use the updateusr function from the
> TeachingDemos package to set the user coordinates, then use
> points/lines or other functions that can add to the current
> plot (e.g. contour with add=TRUE) to overlay the information
> of interest to the plot.
I tried this, and your approach works great except for one thing. I
would like to plot to a pdf device, and when I do so my grayscale image
takes on a gridded appearance, with thick horizontal and vertical lines
of lighter gray. These don't appear of course if I use jpeg() instead
of pdf(). How can I get rid of those?
scott.waichler at pnl.gov
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