Re: Action for 4.2 [was Re: with image and reversed x-axis]

[Daniel J S. <dan...@ie...>]

Attached is a patch to adjust the orientation of the image as I suggested in the last email.  Now, this isn't CVS quality.  But it can give you an idea of how to fix this issue.  I've checked x11, PNG, postscript.  Please try other to check if the orientation is correct.

You may notice there is a slight issue with pixel offset by one on depeneding on axis direction.  This weekend I will look at fixing that.  But since we are on this and looking at image innards, we could also address a crossroads Ethan and I came to with a couple things:

1) Flipping in the y direction according to the pixel 1,1 in the upper left corner versus lower left.  It tied in with...

2) Exactly how should position the image?  With respect to the pixel center or the outer edge of a pixel?  That is imagine plotting an image so that it's lower left corner is at (0,0).  Should pixel M,1 (in terms of matrices) center be at (0,0)?  Or should the bounding box of the image be at (0,0)?

To understand what I'm talking about, try this example that puts the borders tightly around the image:

set xrange [-0.5:127.5]
set yrange [-0.5:127.5]
set tics out
set label 1 "Selection of the input channels via \`using\`" at 140,160 center
set title '"I do impersonations..."' offset 0,-0.5
plot 'blutux.rgb' binary array=128x128 flip=y format='%uchar' using 1:2:3 with rgbimage

Zoom in real close with the mouse at the origin.  Since there is no x,y info in this data, gnuplot assumes x=0,1,...,127.  Same for y.

Dan