The python imaging library is pretty good for this kind of thing.
http://www.pythonware.com/library/pil/handbook/
Here's an (untested) example. Hope it helps.
Jake
#!/usr/bin/env python
from pylab import scatter, save
import Image
#get the background image, and find out how big it is
im_bg = Image.open("background.png")
bg_width, bg_height = im.size
#make a white canvas on which to paste the background image and the
scatter plot
#this will allow you to, say, have the x- and y-axis values fall outside
of the background image's limits
im_canvas = Image.new("RGBA", (bg_width+60, bg_height+60), (255, 255,
255, 0))
#create the scatter plot from x and y data with matplotlib
scatter(x, y, s=sizes, alpha=0.75)
#save the scatter plot, and then retrieve it for use in PIL, convert to
RGBA so that alpha levels will work
#there is probably a better way to do this with gcf() or gci()...
savefig("scatter_plot.png")
im_scatter = Image.open("scatter_plot.png").convert("RGBA")
#resize the scatter image to make it fit nice
im_scatter.resize((bg_width+10, bg_height+10))
#bring all of the images together by pasting them onto the white canvas,
use the overlayed image as the mask (third element)
im_canvas.paste(im_bg, (30, 30), im_bg) #play around
with the paste locations (30, 30)
im_canvas.paste(im_scatter, (10, 30), im_scatter) #these won't be
perfect the first time (10, 30)
#save it
im_canvas.save("combo_image.png")
________________________________
From: __ [mailto:[EMAIL PROTECTED]
Sent: Sunday, June 10, 2007 5:22 PM
To: matplotlib-users@lists.sourceforge.net
Subject: [Matplotlib-users] Simple scatter plot over an image
Hello,
I'm trying to plot a simple list of x/y coords over an image (.png). I
can show the image, or plot the data, but cannot find a way to layer one
over the other. I would greatly appreciate someone pointing me in the
right direction. Thanks.
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