From:	CSBVAX::CSBVAX::MRGATE::"SMTP::CRVAX.SRI.COM::RELAY-INFO-VAX"  3-MAR-1989 06:14
To:	MRGATE::"ARISIA::EVERHART"
Subj:	RE: Help! Need to display grey-scale images on VS2000!


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Date:		 3-MAR-1989 09:56:20 GMT
From:		UHAP058%vaxb.rhbnc.ac.uk@NSS.Cs.Ucl.AC.UK
To:		Info-Vax <@NSS.Cs.Ucl.AC.UK:Info-Vax@kl.sri.com>
Subject:        RE: Help! Need to display grey-scale images on VS2000!
Sender:         "JANET UHAP058@UK.AC.RHBNC.VAXB" <UHAP058%vaxb.rhbnc.ac.uk@NSS.Cs.Ucl.AC.UK>
Message-Id:     <20A02E49_00097F84.009213237F37C420$18_1@UK.AC.RHBNC.VAXB>
Originally-to:  $INFO-VAX
Originally-from:UHAP058      "Zahid Hussain"
Mailer:         Janet_Mailshr V3.3a (02-Feb-1989)


Dear INFO_VAX,
    I think the problem Rick McTeague mentions with UIS$IMAGE arise 
from probably not setting the writing mode (UIS$SET_WRITING_MODE). 
The attribute block 0 has defaults which makes it work for a mono WS, 
however for a color WS, this attribute block has to be modified.

For example, the following code (in PASCAL) should work. First, assume 
you have the following image definition:

const
   xsize = 255;
   ysize = 255;

type
   image = array [0..xsize,0..ysize] of integer;

(* The image is a 256x256 array of integer, modify this to the size 
you need and the virtual display and viewport *)
First get the hardware information:

UIS$GET_DISPLAY_SIZE('SYS$WORKSTATION',ws_xwidth,ws_ywidth,xres,yres);
UIS$GET_HW_COLOR_INFO('SYS$WORKSTATION',,indices);

Next crete the virtual display and viewport:

vd_id := uis$create_display(0,0,xsize,ysize,(xsize+1)/xres,
                            (ysize+1)/yres,vcm_id);
wd_id := uis$create_window(vd_id,'SYS$WORKSTATION','PICTURE');

indices will tell you the number of color or grey level you can 
have. NExt create a color map (UIS$CREATE_COLOR_MAP) and load it with 
a color map using either (UIS$SET_COLOR or UIS$SET_COLORS).

Having done all this, you can display the image using the following 
procedure.

procedure display_color_image(vd_id, wd_id : unsigned; var im : image);
var
   i,j : integer;
   buffer: packed array [0..xsize,0..ysize] of byte;
begin
    uis$set_writing_mode(vd_id,0,1,uis$c_mode_copy);
    for i := 0 to xsize do
        for j := 0 to ysize do
            if (im[i,j] > 249) then
                 buffer[j,i] := 249
            else if (im[i,j] < 0) then
                 buffer[j,i] := 252
            else buffer[j,i] := (im[i,j]) :: byte;
    uisdc$image(wd_id,1,0,0,xsize,ysize,xsize+1,ysize+1,8,buffer);
end;


Hope, this helps. Enjoy!

                      ** Zahid.

Zahid Hussain, Ph.D.
Royal Holloway & Bedford New College,
University of London,
Dept. of Physics,      E-mail : JANET:  UHAP058@uk.ac.rhbnc.vaxb
Egham Hill, Egham          BITNET/EARN: UHAP058@vaxb.rhbnc.ac.uk
England, U.K.