[Gnuplot-bugs] rgbimage shift-rotates the image along the x-axis

[fredfriend <van...@il...>]

Dear all,

I'd like to overplot data with gnuplot via "rgbimage". The image that is
inserted is however always shift-rotated.

Normally I use 'with rgbimage' to import some graph of a published article,
but here I'll talk about a 'silly' example:

As an example I generate a postscript file with gnuplot of y=sin(x). I crop
the postscript file in Gimp (for instance) to remove the tick labels etc so
that I'm left with the sin(x) plot and the borders (which run from -10<x<10
and -1<y<1). The cropped image is then saved as PNM image which I can read
into gnuplot if I know the size in pixels.

Then I want to 
plot "bla.pnm" binary array=639x887 format="%uint8" flipy not w rgbimage

and I get the following result:

  http://www.nabble.com/file/p25472029/gnuplot.png 

please ignore the silly 90deg rotations of the axes, this is just due to the
'convert' program. The explanation is as follows:

The image is **properly** put from 0 to 639 on the X-axis and from 0 to 887
on the Y-axis. As you can see the top of the imported image (i.e. the top of
the sine wave) is cut off and put below the bottom. 

It is therefore 'shift-rotated' along the X-axis.

I looked at the imported image (the PNM) with different programs and there's
no shift apparent in the image itself, so I think it's a gnuplot thing. I'm
using gnuplot 4.3.0 and had this problem with several imported images from
different sources.

Can anybody reproduce this error? Is this a bug of gnuplot?

any help would be much appreciated! 


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