It is true that if you turn antialiasing off on GV then the effect seems to disappear but that is just a cosmetic thing. Other aspects of the figure are subsequently degraded, however. I am really interested in converting the postscript to good JPEG images and I can't get rid of the annoying lines when I use display or convert (in LINUX). If I could figure our how to get a good JPEG figure I would be satisfied. Thanks for any help.
paul murrell wrote:
Hi
Full_Name: Jonathan Lees
I am having trouble with the postscript output of images.
They have lines on them that are not supposed to be there.
I have noticed this on numerous trials of printing various images.
I looked at the postscript and I see that it
appears to plot each individual block - so perhaps occasionally the
space between the blocks "leaks" through do to round off,
thus contaminating the image.
this could be solved if the image software used postscript
image plotting functions.
Here is an example of some code:
postscript(file ="test.ps" , onefile=FALSE, print.it=FALSE)
w<-5 #width of central square
m=w
xn<- 128; yn<- 128
im<- matrix(0,nrow=yn,ncol=xn)
xc<-floor(xn/2)+1;
yc<- floor(yn/2)+1 # centers of the image
im[(-m:m)+xc,(-m:m)+yc]<- 1
image(im , col = cmap ); title('im=Original image')
dev.off()
view this output with any postscript viewer (or printer)
and you will see extra lines on the plot.
Is this just caused by antialiasing on the postscript viewer. I see this with anti-aliasing on, but it goes away if I turn antialiasing off. Of course, that wouldn't explain the effect when a document is printed, but I don't get that. Paul
=============================== Jonathan M. Lees Associate Professor University of North Carolina Department of Geological Sciences CB#3315, Mitchell Hall Chapel Hill, NC 27599-3315 VOICE: (919) 962-0695 FAX: (919) 966-4519 EMAIL: jonathan.lees@unc.edu http://www.unc.edu/~leesj