iraf.net

> Ok, version 2.9, sun operating system 403, imtool window size = 512x512,
> image size before 62x58, after 123x115. Display it then zoom in using the
> mouse, to maximal magnification. The pixels do not look square, in fact they
> vary over the image. ^^^^
^^^^^^^^^^^^^^^^^^^Eric, I think you are seeing adjacent pixels with the same mapped
greyscale/color value. IMTOOL on an 8bit workstation uses 200 greylevels
for image pixels (see the imtool manpage). Consequently, if there are more
than 200 pixel intensities in the input image as mapped by DISPLAY and sent
to IMTOOL, even if every raw image pixel had a different value, there would
likely be a number of adjacent pixels having the same color/greyscale, making
it look like a rectangular pixel. To test this, turn on cursor position
reporting with the F6 key with the mouse in the imtool window, and look at
the pixel number (shown as a real number, e.g. 61.56 is pixel 61, .56 of the
way through) as you move the mouse around. When the mouse is in what you
have been thinking of as a non-square pixel, the pixel number should change
as you move the mouse from one end to the other of the pixel.Steve Rooke (iraf@noao.edu)