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

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

addition information to the report below:

I **can** properly plot the rgbimage in octave, even though this octave
3.2.0 uses exactly the same gnuplot binary.

(   in octave I simply do:  imshow('bla.pnm')   )




fredfriend wrote:
> 
> 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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