Advanced Colour Enhancer

GTH's ACE colour corrector looks 
unsophisticated, but offers an easy 
way to fix video colour problems

(GTH Note: This review naturally takes the videomaker's viewpoint. However the ACE works with ANY video source and will also correct other people's mistakes or equipment faults! Home Cinema owners wanting perfect results also find it ideal.)

Here’s a question. Why, if you had the sophisticated video editing functions provided in the latest computer-based systems would you need a little box of tricks to perform colour correction functions? The answer - to save time.
    One of the more odious problems connected with non-linear video editing systems is the delay between finishing your edit and seeing the results. The rendering time, during which the computer does all the data-juggling required to take into account your cuts, effects and software-generated titles, can run into hours, even for relatively short clips. Therefore, the last thing you want to do is to add to the rendering time by making small but global changes such as altering the colour balance.
    This is where boxes like the GTH Electronics Advanced Colour Enhancer comes in. Whether you are digitising video into your PC, or outputting to tape, it's much easier to use this sort of box to do picture correction than it is to do it in software and to accumulate rendering time. Just as in the music recording process, where it makes more sense to start with a good recording than to try to 'fix it in the mix,' it saves a lot of time and trouble to correct problems or introduce certain special effects before capturing video clips to the computer.

Colour temperature

Perhaps the most obvious use for colour correction is for footage shot using an incorrect colour balance setting. It's easy to forget when you move from outdoors to indoors or vice-versa that the colour temperature may change - unless the automatic colour balance functions on your camcorder are very good, you might be landed with blue-tinged footage outdoors, or orange-tinged footage under artificial light. Even if shooting exclusively indoors or outdoors, changes in lighting may mean that the colour balance of scenes may not match when you come to edit. The Advanced Colour Enhancer can fix all this, and in such a way that minor changes can be made on-the-fly. Though it looks a little home-made, the ACE is a sophisticated unit using digital processing technology, and we're told that reliability is high and the return rate remarkably low. Built using a brick-sized, plastic, breadboard-style enclosure of the sort you might buy in Tandy, it's nonetheless pretty sturdy and should survive the knocks of studio use. The double-sided board seems to be well-enough designed, and the sockets adequately filtered. We didn't experience any problems with outside interference, so you shouldn't have any worries about placing it on your desktop near your monitor.
    The knobs are of a decent size with centre markings. The buttons are small but have a good positive feel. Around the back are connection sockets for video signals and stereo/mono audio. The ACE has no audio processing functions except a fader, but in any case it's handy to have the loop-through sockets. There are audio, composite and S-video inputs for the source machine and a selector switch to choose which video input is used. There are outputs for VCR 1, and a Scart input/output for VCR2. The video outputs are buffered and can be connected to two VCRs without any level loss. There's also a connector for the external 9V power supply which is provided.


On the front are 11 main knobs and 15 buttons, divided into five main areas. Because there are settings on which the picture would disappear altogether, it's good that there's a Bypass button to override all the processor's effects.
    In the Colour Controls section, Saturation enables you to adjust colour level from zero (that is, b&w) to double normal level, while the Balance control affects the colour balance of coloured areas without changing overall white balance, and is useful for correcting skin tones. The Shift function is for correcting the position of the colour element of the picture, which can often slip out of sync with the luminance element, especially on multiple generation tapes.
    In the White Balance section, you have individual controls for Red, Green and Blue colour levels - apart from correcting colour balance faults, these controls can be used for special effects such as creating a twilight hue or a sepia effect.
    In the Video Controls section, Contrast and Brightness can be adjusted, while in Special Effects you can alter picture sharpness. There's also a Digitise function which gradually decreases the number of colour and brightness levels in a picture, producing a 'paint' effect.
    Of the push-buttons, the Invert Video and Invert Colour buttons can be used separately or together to invert the brightness or colour palette of the image - normally useful only for special effects though it can also be used to copy photographic negatives to video. The Pattern buttons are used separately to produce blank blue or red screens, or in combination to produce the standard European colour bar test image. These two buttons over-ride all others except Bypass.
    Finally, there are Fade/Wipe functions. Though very unsophisticated by the standards of non-linear digital effects software, these simple wipe effects can sometimes be useful; the picture can be wiped to black from the left, right, top or bottom (or any combination), or faded to and from black under manual control, or automatically according to the setting of the Speed knob, from around one to five seconds. With the Audio button depressed, the sound is faded along with the video.


At £250 the ACE colour corrector is not exactly cheap. But, considering the amount of time it might save you, it could be a very worthwhile investment.


Computer Video "RECOMMENDED", Overall Rating 90%

Computer Video, January 1999

Click Here to Return to the
GTH Home Page

Email to: Telephone: 01692 402501 International Tel: +44 1692 402501

Keywords: color, colour, digital, video, processor, standard, convert, converter, red, green, blue, white, balance, contrast, brightness, saturation, hue, sharpness, enhance, invert, aspect, ratio, letterbox, zoom, PAL, NTSC, SECAM, DVD, Betacam, DV, Hi-8, S-VHS, VHS, home cinema, home theater, video processor, colour corrector, corrector, edit, fade, bleed, VCR, bars.