[R] missing lines when using image()

[Tom Bloemberg]

When making an image of a rather big matrix, containing a lot of NA's 
and not that much real numbers, like in the following (rather simple) 
example

M <- matrix(NA,1000,1000)
M[,seq(1,1000,length.out=50)] <- 1
image(M)

information (in this case: horizontal lines) is missing in the resulting 
image. This probably is because the vertical screen resolution is 
smaller than the number of rows in the matrix.

Does anyone know of a general method (apart from the obvious and not 
really general methods of buying a bigger screen, zooming in on part of 
the matrix, and simply not making an image of such a big matrix) that 
causes the missing lines to be visualized?

When I visualized the same matrix in Matlab (my sincere apologies to 
those considering this to be blasphemy), looking at a mesh plot from the 
top, all the lines were nicely visible, so it should be possible in some 
way...

Regards,

Tom Bloemberg