REVIEW: Videoface

This is a device designed for use with the ZX Spectrum 48/128/+2 computers. It’s purpose is to capture composite video, digitize it and present the digitized screens to the computer.

The VIDEOFACE digitizer will successfully operate with the TS2068 through the use of a RAINBOW interface. Other devices which convert the TIMEX 2068 bus to the Spectrum configuration may also work as long as a Spectrum ROM or emulator is used.

Instructions are readable, however not as detailed as might be desired. The user is told how to set up the unit and what video sources may be used. Instructions are also given on loading and using the menu based software which facilitates the control of the digitizer and the viewing of the captured pictures. By carefully following these instructions exactly everything worked as explained.

I set up a modular TV tuner next to my 2068 and experimented with capturing pictures from local channels. While in the scanning mode, digitized pictures are presented rapidly one after the other on the monitor and give the impression of watching a black and white movie projected at a very slow frame rate.

The individual pictures are displayed at a rate of about 2 per second, just slow enough to let you respond to one you like by pressing the SPACEBAR to freeze the display. When you do freeze the display, the previous 7 pictures are stored to allow you to step through them to select one to save. This takes care of the problem of not being able to hit the SPACEBAR quick enough to catch the picture you wanted.

Now that you have captured a picture, what can be done with it? The instructions say that it can be immediately sent to the 2040 printer (if one is currently connected of course). I found that this does not work with either of my 2068’s. If I tried to load the VIDEOFACE software with a 2040 printer attached, it would not load and run! Pictures can be stored on cassette tape as SCREEN$ however, so all is not lost. (The saved SCREEN$ files can be loaded later either in Spectrum or 2068 modes when you are not running the VIDEOFACE software, and can then be viewed and printed just as you would with any other SCREEN$.)

These pictures make great graphics for use as loading screens or in the body of your programs. I have added several to both purchased programs (as loading screens) and to programs which I wrote. This really dresses up your software and is impressive to see. If you have access to a video camera you can also send pictures of yourself, your TIMEX equipment or anything else you like to your friends on cassette! Another use is to create header panels (pictures) which can be put on your VCR tapes. By making your own custom headers your VCR tapes can start with your own special artwork with your name, date, name of the tape or what-have-you!

I did have one problem using the VIDEOFACE unit. One of my 2068’s had difficulty in that the pictures would be distorted with vertical lines. This was resolved by changing the original Z80 chip in the 2068 to a Z80B which has much greater bus drive capability. It seems that the VIDEOFACE digitizer presents a heavy load to the bus which may also explain why I can’t load their software when the 2040 printer is also attached. If you should try one of these digitzers and have problems with distortion keep this fix in mind.

I have really had a lot of fun with the digitizer. Special effects are possible by using the video threshold adjustment on the unit. This sets the video brightness level at which each pixel becomes black. (Remember that we do not have gray scales with our computers, the only choices for the pixels are ‘on’ or ‘off’. Adjusting the threshold level can be thought of as the exposure level when taking black and white photographs. You can make the pictures look quite different by how you set this adjustment. Other ways of creating special effects are through use of graphics programs which allow loading of existing SCREEN$. I used SMALL SCREEN PAINTER (SEPTEMBER 1986) which is ideal for reworking digitized pictures.

G. W. Goegelein
Phoenix, Arizona

Editors: Check out the SLIDE SHOW made with ACTUAL SCREEN$ digitized with VIDEOFACE!

From:
DATA SKIP
Lange Willemsteeg 12-14
2801 WC GOUDA
Holland