Basics of color correction/monitoring

[Dave Haynie]

[George Whitburn] “For a while now I’ve been editing photos and videos directly on my laptop, an HP Pavilion dv7. It’s a special edition so I don’t know the exact model number. It’s a decent laptop and it usually does the job for me.”

I have an HP laptop, too. They’re dandy laptops, but the screens, like most, are usually TN LCD. Which means high speed, narrow viewing angles, and questionable color. And if you don’t color calibrate on a regular basis, really questionable color. That’s true of ANY display.

[George Whitburn] ” From what I understand, most good monitors use DVI-D. I’m fairly certain someone sells adapters but I have to wonder if that’ll screw up how the color looks on the good monitor.”

Actually, given that DVI-D is a digital interface, there’s no possible way that the color is lost along the way.. largely because the interface isn’t sending color. It’s sending an 8, 10, or 12 bit (well, not sure where the DVI limits are) per pixel value, which is interpreted by the monitor. You pretty much either get the complete signal to the monitor or nothing.

But in fact, even less worry. HDMI is a superset of DVI. It has the same signalling conventions, different connector, and higher maximum speeds. So if your laptop, as mine does, puts out HDMI, you can use a cable (no actual converter needed) to route the right signals to the DV connector. And it has no possible effect on color. There are some HDMI rates DVI devices don’t necessarily support, but digital devices also handshake, so your PC isn’t going to send a signal the monitor doesn’t understand. Those days are pretty much over.

As for monitors and calibration… first the monitor. I have a pair of MVA LCD monitors, which were the best technology for color and video some five+ years ago. MVA and PVA are pretty much gone, due to IPS LCD falling in price and improving on video. Starting today for a photo/video screen, I would certainly not by a plain TN screen, and probably find a good IPS display (IPS, TN, MVA/PVA, and others are different LCD technologies.. there’s a good Wikipedia article on this if you’re curious on the technical details).

Next, calibration. You calibrate a monitor by running software on your PC that talks to a calibration sensor (officially dubbed a colorometer) .. a small hardware wand, usually something that sticks to your screen(s). I use an older Pantone product called Huey Pro, which is a fairly cheap model, but does the job. Basically, the software displays various color samples on the screen, which is going to be under the wand. It reads that back, and the software computes the changes necessary to make the reported color match the expected color. Most modern OSs (MacOS had it first, Windows has for awhile) support color calibration in the OS. The Huey Pro also works as a room light monitor when not doing the calibration .. that’s more important for photo work, I think, than video.

Do you have to calibrate differently for photo and video? It’s not necessary, but it’s probably a good idea. The color temperature and gamma standards for video aren’t the same for print. So if you’re working on video, you’re usually standardizing on 6500K light and a gamma of 2.2. Prints may have other setting.. I think 5000K is popular for printing. The calibration allows what you see to show up on paper or screen, regardless.. but the lighting you’re going to view a print under will change the effective look. And for video, all you can do create something that will look correct on a correctly calibrated monitor.

-Dave