BORROWING IMAGES FROM THE TEE VEE

The SUNSET VIDEO DIGITISER for the Spectrum brings out the best artist in me. I don't know how I do it, but within a couple of seconds I can create the most realistic

pictures ever seen on a Spectrum screen.

SUNSET VIDEO DIGITISER
Price: £128.00 inc P&P
Sunset, 3 New Road, Famham, Tongham, Surrey GU10 1DF

The possibilities are enormous. Just plug in the family video camera or the rent-a-video recorder and you'll spend hour after hour tracking down interesting subjects

and shading them to perfection for the final print-out. The video frame can be the starting point for an exceptional games loading screen, which can be manipulated

with any screen graphics utility to the point at non-recognition. Or ultimately, the digitiser can be part of the home desk-top publishing system, incorporating

pictures into editorial text for your local family rag. Either way, the SUNSET VIDEO DIGITISER provides lots of fun.

THE PIXEL OF THE MATTER

Now everybody knows that the Spectrum screen is not a bottomless cup of pixels, but a mere conglomeration of 256 x 192 lonely points, so the TV resolution picture

loses somewhat in definition when converted to the Spectrum format. Busy or overcrowded pictures end up rather unrecognisable, but if larger subjects are focused on the perception is definitely good. The lower resolution provides a grainy artistic touch, highlighted by the many shading facilities. Taking a picture results in each point or pixel on the Spectrum screen being allocated one of sixteen values representing the brightness level. This master file is stored outside the screen area and requires no less than 24576 bytes.

As the screen dots can only assume two states, on or off, intermediate levels can be displayed in various patterns of dots. Three grey scale modes are available.

'Black and white' provides just two display levels. The brightness of the picture can be adjusted by setting the trip level between black and white to any of the

sixteen values. 'Black white and grey' divides the sixteen levels into black, white and one grey level. Again, the two boundaries may be set to accentuate the darkness

and the amount of grey zones in the picture. 'Full grey scale' provides black, white and three grey levels and imitates the photographic image on the Spectrum screen

as closely as possible. Again, the grey scaling can be set by varying the grey, black and white boundary levels.

THE DIGITISING UTENSILS

Yes, I'm afraid part of the equipment is encapsulated in the usual black interface box with an insignificant phono socket as a major landmark. A cassette tape for the

software support together with a NLQ print manual comes with the package. A phono cable with two converters ensures access to any type of video equipment (phono plug, BNC socket and plug). Push interface into lifeless Spectrum, link up to video unit, switch on Spectrum and load software from cassette. Camera roll... ACTION!

THE SOFTWARE SCENE

Who doesn't like to be driven by a menu? (It's all that drives Gary Liddon - ED.) Eight options are available - only one modifies the master file containing the basic

picture information. TAKE PICTURE set the 8-bit A/D converter in motion and transfers the video picture to memory. During six seconds, the software has to convert the 8-bit value from the converter into 4-bit data acceptable to the Spectrum memory size. No flash conversion means a rock steady picture required for the six second duration. No wobblies, NO ACTION, in front of the video camera and a pretty good freeze frame facility on the ol' video recorder. Noise bars need to be fought into the bottom edge, or even better into oblivion.

Unsuccessful attempts at grabbing a frame are met with a beep, followed by the PICTURE ANALYSER screen, which displays anything from a missing frame sync to a signal format error; this could be wrong number of lines, wrong line length or wrong field format (Interlace, odd, even).

Successful frame grabbing can be improved upon by SET INPUT LEVELS. Maximum and minimum levels representing the contrast of the current picture are analysed and evaluated for a further take. The second scan converts the 8-bit data with a corrected ratio into 4-bit giving maximum contrast.

MOVE INCOMING PICTURE takes into account the fact that only part of the TV picture is transferred to the Spectrum and allows the conversion window to be positioned

over the relevant TV screen area for a further take.

GREY SCALES enables the selection of the parameters responsible for the interpretation of the master file data into screen representation. All three grey scaling modes have a bar graph for the selection of the boundary levels (brightness and grey shade control) while PRINT PICTURE ON SCREEN converts the master file data into a screen picture using the aforementioned parameters.

Having lost all the colour information of the original TV picture it might be a good move to display the mono picture in different colours. CHANGE DISPLAYED COLOURS

does this at a touch of a key. Unfortunately, there is no provision for changing the border colour. Individual colouring can be accomplished at a later stage once the

screen has been stored to tape or cartridge using SAVE/RETRIEVE PICTURE to save the screen picture as a screen file or save and load the master file for further

manipulation at a later stage.

Provision is made for producing a backup copy of the software onto cassette or Microdrive cartridge. The reverse side of the cassette contains a print driver routine

which can be set up for various printers and printer interfaces. The manual gives a detailed explanation of the control program and provides the programmer with call

addresses for the various machine code routines.

CUE AND REVIEW

The SUNSET VIDEO DIGITISER is not a cheap add-on for the Spectrum. Unfortunately it is one of those devices which grab your imagination and you'll find yourself spending far too much of your valuable time designing excellent looking screens with the least possible artistic requirement. No news yet on the printer ribbon that allows you to make iron-on transfers of your pictures for application to shirts - more details next month, hopefully.

SUNSET VIDEO GETS IMAGE CONSCIOUS

Just when I thought I'd seen every possible use for the Spectrum, Sunset came along and turned it into a camera.

The Sunset Video Digitiser takes still images from a video camera or video recorder and displays them on screen - and costs £128.50.

Once the picture is in the Spectrum you can manipulate it by altering the grey scale - each pixel is stored at one of sixteen levels - and print it to a printer. This last feature was omitted from the review model but all you have to do is Copy the screen.

As the Spectrum cannot display the whole of a normal video picture you can select a part of the incoming image, roughly two thirds, as the picture.

Generally speaking, the whole process is fairly automatic. You control the overall grey scale but basically you must input a still frame, press a key, and in theory the picture appears.

In practice it proved a little more difficult than that. The first attempt worked find first time, while the second took half an hour to achieve only a poor quality picture. The problem is that you need a high-quality picture and a home video recorder usually isn't up to it.

For the enthusiast, with the necessary video hardware, the Sunset Digitiser is a must. You could create all sorts of images, load them into a graphics program and end up with some stunning pictures.

For the home user, think carefully before you buy.

Sunset, 3 New Road, Tongham, Farnham, Surrey. Tel: 01-681 8702.