Saturday, June 27, 2009

Why Display Port? Part 1 of 2


If you have been involved with computers for any amount of time, you may very well be reaching your point of maximum tolerance for sheer number of connection and slot types available. As the pace of advancement has accelerated in computers themselves, advancement and evolution of the methods of interface with these systems continues to accelerate in kind.

Display interface may not have been changing with quite the speed of hard drives and other peripherals, but for those of us who use computers in video post production, it’s become a chore to determine how to construct a signal path and monitor combination that can be considered “evaluation” quality as CRTs fade into the sunset.


When VGA (Video Graphics Array) was introduced in 1987, it was certainly a step up from its predecessor, EGA, which could choose 16 colors, and added the ability to choose those from a palette of 64 possible shades over its predecessor, CGA.
Of course, then we moved to Super VGA, XGA, WQVGA, WXGA, WSXGA, WUXGA, WQXGA…and on and on…ever increasing pixel count and color precision.



Of course, as displays changed, requirements changed in the way we fed them a signal as well. Flat panel displays had pixels instead of a CRT’s analog scanlines. Enter the Digital Visual Interface, or DVI connector in 1999.



Of course, the great thing about the standard DVI connector is that there are 5 different models. They are each just different enough to make many technicians misidentify them about 50% of the time, but to make them incompatible about 75% of the time.
A DVI-I connector (“I” for “Integrated”) can carry analog as well as digital information to be backwards compatible with analog displays. A DVI-D connector is “Digital” only. The fact that there even IS a DVI-A (“Analog only”) connector defies logic as the reason for DVI’s development was to overcome previous analog display cabling limitations. There is an M1-DA connector that integrates USB with digital and/or analog signals, and of course, the DVI-DL (“Dual-Link”) is what is necessary to run those spiffy 30” LCD displays at full native resolution because of its additional payload capacity.

All this has been expanding the capabilities of our computer displays quite rapidly over the last decade, but for video production professionals, 24 bits per pixel has started to become a bit limiting (DVI Dual-Link does have the capability to convey 48 bits/pixel in specific applications).

As displays have shown up with 30 bit color precision, (see more about HP's DreamColor here) in a new pipeline was needed. HDMI can handle the color, but as a data display driver, it didn’t quite have the necessary flexibility.





TimK


Thursday, June 11, 2009

One of my favorite explanations of color balance...

The fine folks at Cambridge in Color have a very helpful explanation of color balance. (among other things)

The concepts behind light and color are key to the work we do with images both in the field and in post. Check out the article which includes several solid visuals...

TimK