One issue you might come across with DVI signal is the occasional/momentary presence of lines or flashes of light color (in my experience often a light green, purple, or blue). The flashes often only appear for a second or less, and may, if you look closely, recur at the same point in a video roll or at the same slide in a presentation, every time its on screen.

DVI image spikes, a rough representation

I can reasonably confidently put the issues I’ve experienced down to being a bandwidth issue and/or being related to electrical/electromagnetic interference between source and projector/display.

I’ve come across two methods for decreasing the occurrence of these issues:
1. Lower the brightness at the source: This will, in turn, lower the ‘output levels’ from the source, and will require less bandwidth (and is less likely to hit ‘peak levels’) once the signal gets to the projector. There are other ways to lower the output levels or prevent peaking, but this is a cheap and nasty way and it’s a good trick to know if you’re limited on resources.

2. Use a DVI signal regenerator/equalizer in line between the source (vision mixer/switcher) and projector. Something like a DVI Gear DVI Detective should, in theory, do the trick. Although there are so many of these devices out there and often it’s difficult to determine what each device actually does beyond simply joining two cables together. You should look for a device that’s specifically designed to reduce or eliminate electrical interference.

Most of the issues of this type that I’ve experienced have been while using Barco/Folsom mixers and switchers, often with Apple MacBook Pro or Mac Pro machines via DVI (although I’ve seen it with HDCAM sources connected via HD-SDI), and running DVI-D over fibre-optic cable to a projector (Christie, Projectiondesign, Barco). I’ve seen the issue at 1400×1050, 1920×1080, and 1920×1200.

If anyone else has other ideas or ways to address the issue please feel free to comment!