IMG Scan

Reviewed by John S Davison

 

Issue 31

Jan/Feb 88

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A scanner could cost you up to 1000 and although digitisers are more reasonable you still need a video camera. Is there a cheaper alternative?

John S Davison finds one that seems to do the job

 

Ladbroke Computing

99.99

 

This has to be one of the most innovative accessories for the ST yet. It's a device for scanning and digitizing images without using an expensive video camera. In fact it's not video based at all, but works on a similar principle to a fax machine. This means IMG Scan can only digitize printed material. It's capable of handling photographs, drawings, pictures from magazines, and similar items.


To achieve this at such a low price the designers obviously had to make compromises. The main one was that they only provide the software and optics of the scanner YOU have to provide the scanning mechanism. This doesn't mean you need a degree in mechanical engineering, as you may already own the necessary equipment without realising it, your printer!


This isn't as crazy as it sounds, just a product of lateral thinking. Consider this for a moment a dot matrix printer can reproduce acceptable pictures and graphics by building them up from rows of dots. What if we could reverse this process and cause the print head to become a 'read head', and recreate an existing printed picture as a pattern of pixels in memory? Well, it's now possible IMG Scan does just that!


In fact IMG Scan goes one better than that. It doesn't simply read dots from the paper it actually measures and digitizes the image brightness levels at many points along each line. This makes it possible to digitize an image containing varying continuous tones such as those found in photographs.


The only requirement is that your printer should be capable of handling one-time variable form feeds no problem for most graphics capable dot matrix printers. IMG Scan comes pre-configured for use with Epson compatible printers, but you can easily reconfigure it for your own printer. My Star SG10 worked fine on the Epson setting after some initial experimentation with its DIP switches.


The package includes an ST cartridge and image cable; a disk containing scanning and ancillary software; a photocopied picture for test scanning; and an inadequate eight page instruction booklet (with a small supplementary README file on disk).


THE HARDWARE


Emerging from the cartridge is the 'image cable' in reality a pair of flexible fibre optic cables each about three feet long. These cables are clipped together at their. free ends, with the two exposed fibres constituting the 'read head'. With the cartridge plugged into the ST's cartridge port and the power turned on, a dull red light can be seen shining dimly from the end of one of the cables. Apparently IMG Scan uses infra-red light to illuminate the image it's scanning, with the light source contained in the cartridge. This is good design, as it provides immunity to variation in ambient light levels.


The other cable 'reads' the light reflected from the image and directs it to an infra-red sensor, again located inside the cartridge. Other circuitry must then convert this analogue signal into digital values and feed them to the software for processing and display.


Before using the system you have to remove the printer ribbon and attach the free end of the image cable securely to the print head, with the fibres pointing straight at the paper. The optimum position can be found with help from the scanning program. With white paper in the printer the end of the image cable may be moved back and forth until the lowest possible reading is obtained on a scale displayed on the monitor. You then fix the cable in place.


The main problem here is that Ladbroke provide no means of attaching the cable to the print head, merely suggesting you use sticky tape. With a bit of thought I'm sure they could have provided something better, perhaps based on Velcro pads? You also have to be careful that the cable can't catch on any of the internal parts of the printer during scanning. Forget this and you could end up with a nasty (and possibly expensive) mess on your hands.


THE SOFTWARE


The disk contains a number of programs, the main ones being those involved in scanning. The scanning program comes in two versions, for high and low resolution displays. The low-res program handles 16 shades of grey and is more advanced than the high-res version, which currently only operates in a simple black/white mode. A new release with grey scale support is promised soon, available free to registered users. I used only the low-res version for this review.


The scanner program is mainly mouse controlled, with keyboard input necessary only when you want to change its basic operating parameters. It has a menu screen and an image display screen, the former containing the system's main controls and the latter used for viewing scanned images.


Before a picture is scanned you have to calibrate the system using the scanner program's 'Auto Grey Adjust' feature. This involves performing a single pass calibration scan across the picture's area of greatest contrast to determine the picture's distribution of grey tones.


A full scan may then be done. With the top of the picture level with the image cable, a click on the 'scan' box causes the menu screen to be replaced by the blank image screen and scanning begins.


The scanning program drives the print head back and forth across the picture. On each left-to-right pass the image cable digitizes a strip of the picture producing up to 320 data points, each set to represent a shade of grey. These are used to plot pixels of the appropriate shade on the screen as the scan progresses. It's fascinating to watch as the picture slowly grows into a recognisable image before your eyes.


After each pass the paper is advanced, the print head returned, and the process repeated. This continues either until you interrupt it or a full screen image (200 lines) has been generated.


Printer and screen scan line widths may be varied independently, so it's possible to 'squeeze' and 'stretch' the image to some extent during the scan. There are also zoom and positioning controls allowing parts of a picture to be picked out and displayed on-screen in different sizes. It takes up to about 6-7 minutes for a complete scan depending on the image size required.


It's possible to interrupt the scan at any point, make the picture lighter or darker, and continue scanning where it left off. In fact, this can be done with completed images too. The program contains clever facilities for adjusting and recalculating the grey scale to produce a contrast range to your liking or to bring out the image's finer detail.


COLOUR IMAGES


IMG Scan digitizes to 16 grey levels, but the ST hardware limits you to displaying only eight of them. This is achieved by pairing levels, which results in loss of image detail. To retrieve the detail you can use shades other than grey. In fact, you don't have to use grey shades at all as it's possible use colours instead. By assigning a colour to each of the 16 grey levels via on-screen RGB sliders you can achieve up to 16 different colours. It's not the same as a true colour scan, of course, but with care and the right subject you can produce pleasing results. The disk contains several examples in grey shades and colour, showing just how impressive the results can be.


The completed image may be saved to disk as raw data, or in DEGAS or NEOCHROME format. This opens up the possibility of further editing and embellishment using those programs. It also gives compatibility with many other graphics oriented utilities now available including desktop publishing systems. So at last there's a low cost method of getting digitized photographs into your publications!


The disk also contains a utility called AIM, designed to improve clarity, extract features and add special effects to scanned images according to the README file. There were no instructions whatsoever for using it, and my attempt to load it was greeted with a message saying it needed more than the available 512K to run in. Pity, it sounds interesting.


Other software on the disk includes a utility to convert image data into AIM format and back again, and one to convert image or AIM files to POSTSCRIPT format for printing on a suitably equipped laser printer. There's also a simple 'picture show' program for displaying the three sample images provided.


IS IT PRACTICAL?


Yes, it works and surprisingly well. It takes practice to produce good results, but it's well worth the effort. The basic hardware and software does everything Ladbroke claim, and if they're true to their word there's even better to follow as the software is developed further.


It's worth noting that all software updates will be available free to registered users, a very enlightened and welcome approach by Ladbroke.


One thing they really must do is produce a decent instruction manual talk about spoiling the ship for a ha'porth of tar! And a quick and effective method of attaching the image cable to the print head is desperately needed too.


These are minor niggles though and if you need an inexpensive method of getting digitized pictures into your ST then this is it.

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