smith%eri.DECnet@MGHCCC.HARVARD.EDU ("ERI::SMITH") (06/29/87)
I have been trying to use the 2 bitplanes of the vt240 to display a grey-scale image that has been thresholded to contain only 4 levels (00, 01, 10, 11). According to the VT240 programmers reference manual, the beast has 2 bitplanes. It is obvious that there actually is 2 bitplanes since I have observed blank, low intensity, medium intensity and high intenstiy graphics on the screen. I am downloading the image to the vt240 using sixels. I have verified however, that when I download the sixel data, it is going into both bitplanes, and therefore I am only getting 00 and 11 as my levels. Therefore, I thought that if I go into ReGIS mode and mask the appropriate planes (using the ReGIS W(F0-3) commands), I can allow writes to plane 0 only send the 1st bitplane allow writes to plane 1 only send the second bitplane. Unfortunately, every time I exit ReGIS mode and go back into sixel mode, the screen is erased !! I actually have done a 4 level display using ReGIS, however this method is SIXTY times slower than sixels. I am hoping that someone can tell me how to do it using sixels. ---------------------------------------------------- Bob Goldstein goldstein%eri.decnet@mghccc.harvard.edu Eye Research Institute of Retina Foundation 20 Staniford St Boston, MA 02114 (617) 742-3140 x404 ------ ------ ------