I'm not sure I understand your question, but can you just use par("usr") to get the x,y-limits of your image plot and dim() on your matrix for the number of pixels? Then all the points on the image (in your user coordinates) should be known.
I don't know if this would help but I think you can convert jpeg images to bitmaps for R to read using ImageMagick. --- Peter Stencel <[EMAIL PROTECTED]> wrote: > Dear R users, > > I've two questions: > > 1) Does anybody have a clue how to convert pixel from a jpeg graphic (e.g. > something like a square of 100x100 pxs) into axis coordinate values in R? > > 2) Is there any possibility to extend the R locator function in a way that > locator( ) outputs all coordinates from a plot at once, without clicking on > the graph? > > Thanks for any hint. > > Regards, > P. Stencel > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ____________________________________________________________________________________ Get your own web address. ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.