IDL PS errors



email: gsg@debye.mit.edu
I have noticed that the imaging routines in IDL when using "set_plot,'PS'" do not display certain rows and columns i
the following gif images AR-all 2000x500 images that should show continuous lines of 50 raster segment that go up one raster every 50 rasters. In the particular cases I show, the gaps are obvious, some times only occasional, some times being more than the visual lines.

In each set, the two images are just rotations of each other. In each case the lines were generated going from left to right in the left image. The right image I just rotated the array before plotting it.

I think that this might why the spectrograms I have produced using IDL have not shown detail I expected. I am questioning how to proceed to make and print spectrograms without GIPS. I will at least come into MIT and try different devices in IDL. Clearly 'PS' is not reliable. What devices have other people tried? For your info, the IDL procedure I used to generate these images is "test_im.pro" I think the error stems from PS using integers, resulting in roundoff errors.
To make things even wearder, I increased the y axis by 1 to 501 (This allows an extra segment on each scan) and see what I got.