[R] convert pixels into axis coordinates in R

[Peter Stencel]

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