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Newsgroups: comp.graphics.apps.gnuplot
Date: Mon, 28 Jan 2013 19:31:13 -0800 (PST)
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Subject: Re: plotting data over png image
From: awimagic@gmail.com
Cc: sfeam@users.sourceforge.net
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Xref: csiph.com comp.graphics.apps.gnuplot:1589

On Monday, January 28, 2013 8:22:28 AM UTC+5:30, sfeam wrote:
> 
> You can assign an origin and scale to the PNG image using the keywords
> 
> origin=		coordinates of the lower left corner
> 
> dx=		units per pixel
> 
> dy=		units per pixel
> 
> 
> 
> The online demo collection has this example:
> 
> 
> 
>     http://gnuplot.sourceforge.net/demo/barchart_art.html
> 

excellent! many thanks 

p [-1:15][-1:15] 'cave.png' binary filetype=png origin=(-1,-1) dx=0.032 dy=0.032 w rgbimage, 'all.txt' u 2:3 w l

achieves what i want. except the overlaying of a grid on top. guess the png is hiding the grid lines.