Video/Graphics Workstation

OVERVIEW

The bass.open.dal.ca video workstation is a SUN SPARCstation 1+ equipped with a 24-bit graphics display board from IMS. It operates SunOS 4.1.3 and OpenWindows 3.2 (a.k.a. Solaris 1.1) with an X11R5 server supplied by IMS. This video workstation and its software is capable of the following image/video processing tasks:

displaying video
capturing and displaying single images from video
capturing video sequences and playing them back
converting image formats
outputting images and animation sequences to video

This video workstation is also equipped with a local hard disk drive for storing data to be used on this workstation, mounted on /data. Commands described in this text are stored in /export/bin.
Before using any of the commands outlined in this document, it is suggested that your PATH is altered to include /export/bin using the following:

   bass$ export PATH = /export/bin:$PATH

24-BIT GRAPHICS DISPLAY

What is it?

The IMS 1000/1001 video boards are used to display and compress 24-bit (or "True Color") images. What this means is that the number of colors used to display images is about 16.7 million colors, which results in a better looking display of 24-bit images. Standard 8-bit ( or "Pseudo Color") displays rely on color palettes that limit the number of colors displayed. This basically means that images look more realistic when displayed on bass.open.dal.ca.

How is it different?

This workstation uses a unique X-server (supplied by IMS), and therefore some software might not work as expected. Some programs might require you to tell it that you are working with a 24-bit display, such as mpeg_play. To use it, type:

   mpeg_play -dither color  filename.mpg

Other programs may also require you to set options either on the command line or in a configuration file.

VIDEO INPUT

The Hardware

The IMS 1000 is used to input live video into the computer. This board is located at the far right of the workstation base (when looking at it from behind).

It has 3 video ports numbered left to right, which you can use to plug in video sources. All of these ports are of an s-video type. You can also use composite video (from a normal VCR or camera) by using a custom made RCA to s-video cable. Simply plug the RCA end into the video out of your video source, and the other end into the IMS 1000 board (port 1, if unoccupied) on the computer. If you are using S-VHS equipment, then plug either end of and s-video cable (4 pins and slightly crimped) into port 1 of the IMS board, and the other end into the video out of your video source (VCR or camera).

DISPLAYING VIDEO

To start, type init in an xterm window. This initializes the video hardware. You should soon see a window pop up. This is the Live Video window. This window is the display for data that comes in and goes out of the IMS hardware (see Displaying Images). Click the left mouse button twice inside this window to get the controls window (seen below).

Next, click on the VTR button in the bottom left corner. Then click on the appropriate Format button (ntsc-composite for normal video sources like video cameras or normal VCR's, or ntsc-svideo for S-VHS VCR's).

The source can be from any of three video input ports, depending upon what video sources you have plugged into the back. ExpBus is the expansion bus, which shows you what is coming out of the IMS1001 board (see Displaying Images). Normally port 1 is used, but it doesn't really matter, as long as you have the appropriate one selected from the Source menu (on the left of the controls window).

The size of the window can be changed by either grabbing the corner of the window and pulling it in the usual way, or by using the buttons located near the top of the contols window. It is recommeded that you use the buttons to keep the correct aspect ratio. For the best display, use Full Size because Largest or Max Size distorts the picture.

The Pixel Offset and Row Offset move the image up/down and left/right in the Live Video window only, not the output to the VCR or monitor.

Other video contols are located at the right of the window for fine tuning the picture. These are Gain, Hue, and Bias. You can experiment with these for the best looking picture for you, but default values will usually look fine.

SINGLE FRAME CAPTURE

This will capture a single still image of whatever is being displayed in the Live Video window (see Displaying Video). Type the following commands:

   init                 (see Displaying Video for explaination)

   getstill filename  (.cjp will be added automatically)

The image is now saved as filename.cjp, and can be viewed using showstill. (see Displaying Still Images).

MULTIPLE FRAME CAPTURE

This will capture a sequence of images of whatever is being displayed in the Live Video window (see Displaying Video).
Type the following commands:

   init      (see Displaying Video for explaination)
   getmovie numframes Qfactor filename   (.sjp will be added automatically)

where
-numframes is the number of frames you want to capture.
-Qfactor is the compression factor (smaller means better resolution, while larger means more frames per second).

A file showing the times of the captures will also be written to disk as a file named capture_times (thanks to Dan Kelley).
To play back this file, use showmovie (see Displaying Animations).

DISPLAYING IMAGES

When displaying any image or series of images, you must have the ExpBus selected as the Source on the Live Video window in order to see what is being outputted. Also, refer to Displaying Video for instructions on setting up the necessary video parameters.

Displaying Still Images

To display a still image (.cjp) on the monitor or in the Live Video window, you must first input that image into the framebuffer. This can be done by using the showstill command.

   showstill filename.cjp

If you instead want to view the image directly on the screen using a standard image viewer, you must convert the .cjp file to a .jpg file (see converting images).

Displaying Animations

Animations in the IMS format (.sjp) can be viewed using showmovie.

To display .sjp files, type:

   showmovie filename.sjp [delay_time]

delay_time (time between frames) defaults to zero, but the playback can be slowed down by specifying a number of milliseconds between 0 and 1000.

VIDEO OUTPUT

Hardware

The ims 1001 board uses a framebuffer and a JPEG compression routine to output images to the VCR or monitor.

Setup

The IMS 1001 board is located at the far left (when looking from the back of the computer).

It has 2 ports. The one on the left is for composite video (VCR or monitor) and the one to its right is for s-video (S-VHS VCR's). To use the composite video port, you must use the supplied rca to S-VHS cable (shouldn't be far from the workstation).

Output to VCR or Other Devices

Anything that is inputed to the framebuffer by using showstill or showmovie (see Displaying Images will be immediately outputed through these 2 ports. this means that anything you can see in the Live Video window will go to a VCR or other device, assuming correct connection (see Setup).

Advise on Creating Images

Images created on the computer will not look as good when put on video. This is because videotape does not have the same resolution (sharpness) as computer monitors. This means that care must be taken when creating the images in the first place.
Some things you can do to improve output are:

make objects within your image as large as possible (within 640x480 pixels)
leave a border around your image so that it doesn't get cut off at the edges (35 pixels from each side, 45 pixels from the top, 20 pixels from the bottom)
use large and thick typefaces for words
use yellow or white lettering on dark backgrounds
use dark blue or black on light backgrounds
outline letters in colors that contrast the background (black background, blue typeface outlined in white)
use contrasting colors to make things distinct
use colors that aren't extremely bright (such as the brightest red, white, or yellow)
check to see that colors translate to video properly (usually they don't)
don't try to put too much information in a small area
use thick lines (at least 2 pixels wide) instead of thin ones
outputting to S-VHS looks much better than normal VHS, although you can use normal VHS tapes in an S-VHS machine, you cannot put S-VHS tapes in normal VHS machines

CONVERTING IMAGES

Images can be converted using NetPBM, or by using ImageMagick's convert program. Also, for converting to/from IMS format, the ppmtoims and imstoppm programs are used.

NetPBM is a set of programs of the form ppmto??? or ???toppm.

ImageMagick's convert program uses many of the existing programs such as NetPBM, ghostscript, but has an easier command line structure that allows converting in one step.

IMS format conversions

.ppm -> .cjp
To convert from .ppm to IMS format(.cjp), do the following:

   init                       (see Displaying Video for explaination)
   ppmtoims filename.ppm
   getstill filename         (.cjp will be added automatically)

.cjp -> .sjp
To convert a series of single frame images into a single movie-type file, use the following:

   cjp2sjp starting_frame ending_frame filename_prefix.sjp [output_filename]

The starting and ending frames should both have 4 digits (use leading zero's). The filename_prefix is the path and beginning part of the names of all of the files. The default output_filename is outfile.sjp.

Here is an example:

   cjp2sjp 0001 0100 /data/frame /data/movie

will concat files from frame0001.cjp through frame0100.cjp into /data/movie.sjp.

.sjp -> .cjp
To convert a movie-type file (.sjp) into a series of single images files (.cjp), use the following:

   sjp2cjp filename.sjp [frame]

Frame is optional, and the default is 1. By specifing a number other than 1, only every nth frame will be written.
The filenames of the single frame images will be saved as filenameframe_number.cjp

.cjp -> .ppm
The imstoppm program is what you need to convert the images. This program uses the internal image buffer to convert the image. An example of how to use this program to save images in PPM format is as follows:

   init                      (see Displaying Video for explaination)
   showstill filename       (.cjp will be added automatically)

   imstoppm filename.jpg       (to save the file in PPM format)

Other Notes

Some colors in the original image may not turn out to be the correct colors when put to video. You generally have to experiment with your images colors to get the desired ones.

Another problem with colors being different may be caused by different color maps on different X-windows sessions. This can be corrected by converting the original images to a more general format on the same machine which they were originally created. this is because of a problem with the xwd program.

Image Manipulation Systems (IMS)

17595 Partridge Street Northwest
Andover, MN 55304-1456

techsup@imageman.com

techq@imageman.com

(612) 753-5602

I have been in contact with Larry Lindy from IMS about the IMS 1000/1001 boards, and he tells me that they no longer support them. The above e-mail addresses are valid, but any reply has yet to be received. Their phone and fax support may prove to be different. (Doubtful)

I have been told by Dennis Dingeldein (see Other Users) that someone at IMS named Chris Meier has hacked most of the software. You should probably ask for Chris if you have software problems. They don't really supply software, more like example programs that give you pointers on how to write your own programs, so don't expect any major program advancements.

NOTE: The support software (X11R5 server and sample programs) only work under SunOS4.1.x and OpenWindows 3.x (a.k.a. Solorais 1), and therefore the video workstation (bass.open.dal.ca) will not be upgraded to Solaris 2.x.

OTHER USERS

After requesting information about the IMS boards on the net in comp.graphics, I received only one response. It was from Dennis Dingeldein of ZGDV Computer Graphics Center in Germany. He is currently working on a multimedia project called Theseus++, which uses the IMS 1000/1001 boards. Theseus++ is freely distibutable but since it requires Motif libraries it will not be installed on this workstaion (bass.open.dal.ca).

Dennis Dingeldein

dingelde@igd.fhg.de


ZGDV Computer Graphics Center

Wilhelminenstr. 7

D-64283 Darmstadt, Germany

Phone: +49/6151/155-112

Fax: +49/6151/155-450

He has generously supplied the programs jf2cc and cc2jf, which convert between JPEG and IMS format.

IMAGEMAGICK

This is an image processing package ftp'd from ftp.x.org in /contrib. It will display, convert, animate, scale, rotate, color reduce, and many other functions. It may be useful when processing images to output to video.

These commands are located in the /export/bin directory, and documentation about ImageMagick is available in the /export/docs directory, as well as the /export/man directory.

APPENDIX I, Command Summary

Instructions on how to use these commands can be found in the /export/man directory, or by clicking on the appropriate one here.

init initializes the video hardware.
getstill record single image in framebuffer to disk.
showstill put single image from disk into framebuffer.
getmovie record series of images and stores it to disk as a single file.
showmovie playback series of images from disk recorded with jpshrec.
cjpeg compress pnm files into jpeg.
djpeg decompress jpeg files into pnm or gif.
ppmtoims put a PPM file into framebuffer.
imstoppm take image in framebuffer and output to a PPM file.
convert program that converts just about any standard file format to another (except IMS .cjp format) This program is from the ImageMagick package
sjp2cjp will convert IMS movie files (.sjp) to IMS still images (.cjp)
cjp2sjp will convert a series of IMS still images (.cjp) to an IMS movie (.sjp)
display display almost any standard file format to the computer screen (except IMS .cjp format). This program is from the ImageMagick package
maketitle will make a .ppm title screen from a text file
changenamecjp will change the number of digits in a .cjp file from three to four. It will also add a number to the filename number (if specified)

APPENDIX II, Examples

Converting gmeta frames

This is an example of how to convert a gmeta file into a movie.

bass$ med gmeta

   gmeta with 500 frames
med> split 500

   split into 500 separate frames
med> quit


bass$ init
   script to initialize IMS hardware

bass$ for file in med*.cgm

> do

> gplot -dPSC $file temp.ps

   convert from .cgm into postscript 
> convert temp.ps temp.ppm

   convert from postscipt into .ppm format
> pnmcut 18 190 558 425 temp.ppm > temp2.ppm

   truncate unneeded sides and top / bottom
   Different for every image 
> pnmpad -black -l21 -r61 -t38 -b17 temp2.ppm > temp3.ppm

   add borders to sides and top to make images 640x480
   Different for every image 
> ppmtoims temp3.ppm 
   put image from .ppm to IMS framebuffer
> getstill `basename $file .cgm`

   save image in framebuffer to .cjp IMS format (must be on bass.open.dal.ca)
> changenamecjp `basename $file .cgm`.cjp
   this will output the number in the filename with 4 digits instead of 3
   necessary because most animations will have more than 1000 frames
> done

At this point all of the files are in .cjp format, and all that needs to be done is to combine all of them into a single movie.

bass$ cjp2sjp 0001 0500 med my_movie

Which will save all of the frames into one movie file called "my_movie.sjp" that can be played using "showmovie my_movie"

MATLAB animation

This is an example of how to convert a MATLAB animation into a movie. When starting MATLAB, invert the video for output to the screen by typing:

>> set(gcf,'inverthardcopy','off')

Then to save the current image.

>> print -dpsc frame.ps

,save a series of frames from within a loop.

>> for i = 1:10
      plot ....
      eval(['print -dpsc frame',int2str(i)])
   end

Then convert those frames into a movie.


bass$ init
   script to initialize IMS hardware

bass$ for file in frame*.ps

> do

> convert $file temp.ppm

   convert from postscipt into .ppm format

> pnmcut 18 190 558 425 temp.ppm > temp2.ppm

   truncate unneeded sides and top / bottom
   Different for every image
> pnmpad -black -l21 -r61 -t38 -b17 temp2.ppm > temp3.ppm

   add borders to sides and top to make images 640x480.
   Different for every image 
> ppmtoims temp3.ppm 
   put image from .ppm to IMS framebuffer
> getstill `basename $file .ps`

   save image in framebuffer to .cjp IMS format (must be on bass.open.dal.ca)
> changenamecjp `basename $file .ps`.cjp
   this will output the number in the filename with 4 digits instead of 3
   necessary because most animations will have more than 1000 frames
> done

At this point all of the files are in .cjp format, and all that needs to be done is to combine all of them into a single movie.

   cjp2sjp 0001 0500 med my_movie

Which will save all of the frames into one movie file called "my_movie.sjp" that can be played using "showmovie my_movie"

PPMtoIMS example of transparent colors

The ppmtoims program can be used very simply by just typing the "ppmtoims filename.ppm" to put an image into the framebuffer.

If you want to overlay titles, or images, on top an existing images in the framebuffer, you can use the "-val rr gg bb" option to mask out the background color.

First you need to put an image into the framebuffer. This can be done using any image, for example the Dalhousie logo.

ppmtoims dal_logo.ppm

Then you need a suitable title image. One can be made using the maketitle script (see title making example).

Finally, to overlay the title type:
ppmtoims -val 0 0 255 title.ppm
( 0, 0, 255 means no red, no green, and 255 blue, which is the background color used by maketitle)

Title Making

This is an example of how to use the maketitle program.

Create a text file of up to 10 lines with the desired text be want for the title. For example, this file called title.txt:

Physical Oceanography
OPEN larval tracking cruise

Nov. to Dec. 1992

David Griffin
Keith Thompson

Dalhousie University
March 1994

Then use the maketitle script to convert this text file into a PPM file.

maketitle title.txt

Now we have a PPM file with our title in yellow lettering with a blue background, and every line centered.

Document by Luke Blaikie

blaikie@phys.ocean.dal.ca

April 1994, co-op workterm