[Gnuplot-info] Issue with "image" plot function and incomplete matrix

[<jac...@fr...>]

Hi,

I am using GNUplot Version 4.6 patchlevel 4.
I would like to create a "false" 3D graph: a 2D graph with a color as Z entry.
I find that it could be done easily with "image" keyword (http://gnuplot.sourceforge.net/demo/heatmaps.html)

But my data are not a perfect and simple matrix.
In this case, GNUplot interpolate the data and graph sometime a parallelogram instead of a square...
I would like that nothing is displayed when the point "does not exist" in the matrix.

See 2 following examples, where the graph obtained are false ;-(

How can I correct this ?
Should I use something else than "plot w image" ?

Example 1:
Issue: the yellow square is centered in (2 ; 9) instead of (2 ; 11 )
plot '-' using 1:2:3  with image
1  1  1
1  2  2
1  3  3
1  4  4
1  5  5
1  6  6
1  7  7

2  1  2
2  2  3
2  3  4
2  8  5
2  9  6
2  10 7
2  11 8
e



Example 2:
Issue: the yellow parallelogram is centered in (2 ; 9) instead of (2 ; 11 )
plot '-' using 1:2:3  with image
1  1  1
1  2  2
1  3  3
1  4  4
1  5  5
1  6  6
1  7  7

2  3  2
2  4  3
2  5  4
2  8  5
2  9  6
2  10 7
2  11 8
e

Thanks,
Jacques