D I G I V I E W H I N T S Version 1.0 September 1988 . . . .Bob Downs [Ed: Anyone interested in digitising should read this article by Bob, who's really giving us the benefit of his long experience here. Bob's put together a number of disks of his digitised images, available from him or us. He'll also undertake commissions if required - ask him. The "Digi_Dance.pic" is his of course.] This article is released in the Public Domain on the proviso that it remains intact and is not used for commercial gain. Considering the power of Digiview it is probably one of the most straightforward programmes to use. Yet without exception all users have difficulty producing quality results. This article will show you what hard- ware will be required and how to set it up. To get the most out of the programme will require practice, and plenty of it! This manual was originally intended to be "The Definitive Article," but with product upgrades and continuing R & D by users this could not be done. For this reason upgrades will be circulated as new information and techniques are made available. The current level of developement would not have been possible had it not been for invaluable help and advice from the following; Tim Strachan, Knud Pedersen, Graham and Stuart Boyd, Jon Benjamin, Tom Whiteley, Richard Wynn, Peter Mills and the Technical staff at Channel 9 in Sydney. HARDWARE When you purchased Digiview a plastic four colour frisby was provided to entertain the kids while you were busy at the computer. Unfortunately it is not particularly durable and will quickly break. I suggest that the makers consider using a softer plastic material! Or perhaps discontinue the idea altogether! Before you consider digitizing seriously your first additional purchase should be for the following camera filters. They are obtainable from any well stocked photographic store. Expect to pay about $30 each. For ease of use 55mm or larger should be ultilized. Size is important as you may find it easier to hand-hold the filters rather than to custom build a suitable frame. The filters must be glass. For quality results, DO NOT USE PLASTIC ALTERNATIVES! Red R (25a) Green G (X1) Blue 80b (You will need two screwed together) Matched sets of three filters (RGB POP) are available if you are prepared to wait while they are ordered in. The set will cost about $60, about half the cost of buying them individually as indicated above. Quality glass filters will eliminate most of the "fringing" (red or green bleed where light and dark meet) and will improve the image resolution. If you use an unmatched set of filters you may find it necessary to increase the green value with the slider in the colour adjustment section of the software to improve pictures containing yellow. The green filter recommended is commonly available, but it needs to be slightly darker. When light passes through an object it defracts, different components of the colour will take a different route. For example red will reach it's destination in a different position to blue. Consequently the picture will not be sharp and will contain information not present in the original. To varying degrees the lens you are using with the camera was designed to cancel out this phenomenon by incorporating additional elements. As a rule of thumb, the more elements the better final result. The integrity of the lens will be degraded if a substandard medium is placed in front of it. DIGI-VIEW INTERFACE This unit will plug directly into the parallel port of the A1000, but will require a "Gender Bender" to operate on later machines. LIGHTING This is the second most important area that must be considered and probably the most difficult. Although good results may be obtained with other globes the best results to date have been obtained using two 500W colour corrected Photo Copying globes. These are readily available from well stocked photographic dealers. They will set you back about $30 each. You will also require two screw type globe mounts which are available at Dick Smith and in the electrical section of SOME large hardware stores. Lower output globes such as 250W may do the job but you will find that you will be restricted. In a typical situation 500W globes will give you enough light. Generally the F stop setting would be somewhere between the range of f4 - f8, giving plenty of latitude either side of this setting. LIGHTING SETUP Although each setup is different, use these recommendations as a guide to get you started. The camera should be central between the two globes. That is, the globes and the camera should form a straight line. The globes MUST be behind the face of the lens and should be directed at the subject at an angle of 45 degrees. The globes should be positioned about 1.3 metres apart. Wider settings can be used, requiring a wider opening of the iris (aperture) in the lens of the camera. CAMERA The people from Newtek recommend the National WV-1410N/A security camera. This is an excellent camera. However for digitizing it suffers a serious drawback, it does not support manual override of the Auto Light Compensation. It is not possible to modify the camera to disable this function because the circuitry involved is contained in a chip. Good pics can be produced with this unit but they will appear flat, lacking brightness and contrast. Grain will also be more evident because insuff- icient lighting levels will be passed on to the computer. Whats more, good results can take longer to produce when compared to the recommended camera below. The National camera provides 550 lines of resolution measured at the centre, which is quite good for most purposes. A ready made camera for digitizing is the Hitachi HV720K which has superior resolution (600 lines) and an internal switch to disable the ALC mentioned above. With the correct set-up and experience this camera will produce results comparable to those produced with a broadcast camera. They are distributed by AWA and as an added bonus are cheaper than the National unit mentioned. Quite good results can be obtained with a colour video camera, but not in its standard form. Without modification, pictures will contain strong diagonal lines closely set together. These are caused by the Colour Sub Carrier. This can easily be removed prior to digitizing with a 75ohm Rejection Filter notched at 4.43 Mhz. This should be fitted between the camera and the computer. BNC connectors are provided on the unit. Tube type (as opposed to CCD) colour video cameras generally produce a resolution less than the B&W cameras already mentioned. Check your camera manual. If a colour camera is used vertical mounting will probably be impractical due to the narrow field of view of the lens, requiring the source object to be placed at a greater distance from the camera than would normally be the case. SECOND MONITOR If you have a VCR that allows video in/out and a B&W (or colour) television on hand you will be able to use the television as a focusing monitor. Connect the camera output to the VCR video input, VCR video output to the computer via the digiview interface. Connect the VCR RF output to the television. You will need to tune the television to receive the VCR RF signal. MEMORY To use all the modes of Digiview (PAL version) you will require 1.5 Meg of RAM. However, 1 Meg will provide you with all modes except Hi-Res colour. The programme will not load on a 512k machine. Up to and including version 3.0 release of the software only 16 colours are supported in Hi-Res. This mode is not particularly useful for general work. With Version 2.0 the best quality results will be produced using Interlace. A preliminary appraisal of Version 3.0 seems to indicate an improvement in image quality (over Version 2.0) when using Lo-Res. CAMERA CARE Video cameras give the best results in bright light, yet this can be harmful to the tube, particularly its light sensitive surface. A camera with a manual iris is particularly vulnerable (the Hatachi HV720K has manual override). Tube burns are caused by bright light producing a dark spot on the surface of the tube. Depending on the severity of the burn, it may be removed by turning the camera on and aiming it at a brightly lit white surface for an hour or so. If this has no effect, try leaving the camera operating for a day or two with the lens cap in place. Some spots on the image may be caused by specks of dirt on the lens, or even on the target surface of the camera tube. Use a lens cleaning tissue when cleaning these surfaces. Do not apply pressure as this can remove the lens coating. Take particular care if cleaning the face of the tube as undue pressure will disturb the tube alignment. New and old camera tubes should be inspected. SCREEN WIDTH Use a sheet of stiff (for durability) white cardboard. Draw different sized circles or squares on the card. This will allow settings to be made at different camera distances. Make a single pass and measure the height and width. Adjust the WIDTH in the CAMERA window until both measurements are the same. Each mode (resolution) will require different settings. LIGHT BALANCE As the above mentioned card is white it can also be used to test the lighting balance. For speed in setting-up, use the Lo-Res 5 second scan. Make a single pass and adjust the lights until an even shade on the image is obtained. To get good results you will need to spend some time in this area. JITTER Not to be confused with flicker, jitter is a vertical section of the image up to about 5cms wide that moves rapidly up and down. This is not a problem in Lo-Res. However, in other modes it can be a major disaster. Reducing image sharpness will help but will not eliminate it. The high light levels required with digitizing also accentuate the vertical movement. In the CAMERA window there is a TRACK slider. Like most users you were probably unable to see any modification to the image when you moved this. It's function is to move the offending section of the image out of the screen area. Make a single pass with the red filter in place. If there is any vertical movement in the image, move the TRACK slider one click in either direction. Keep repeating this until a stable image is obtained. Don't dispair, sometimes it can take quite a while. When the red component of the image is correct, try the green (while retaining the red image on screen as normal). If that is unstable you will need to go back to red to make some minor adjustments. If there is any movement when you get to the blue component, display the picture. In most cases it will be stable. UNEVEN COLOUR Sometimes it is possible to produce an image with a darker vertical section on the left hand side about 2cms wide. This is caused by placing a filter in front of the lens just before digitizing. The camera requires a few seconds to adjust to the different lighting. Allow about 5 seconds. FILTER LOCATION The filters should be located as close as possible to the lens. This will help improve the image and will also reduce lens flare caused by light reflecting off the top of the filter. Don't overlook room lighting if you experience problems in this area. CONTRIBUTIONS If you feel that you have tips that can help other users, write to the author via Tim at MEGADISC. As mentioned previously, this article will be upgraded as new information becomes available. If enough interest is indicated (through your letters) other services could be made available. Consideration is being given to compiling a dedicated disk that would include example pics (including faults) ranging from a basic setup to those produced on a $200,000 camera. Let us know what you want, share your work, but most importantly, share your tips! XXXXXXXXXXXXXXXXXXXXXXXXX END OF ABOUT_DIGITISING XXXXXXXXXXXXXXXXXXXXXXX