Saturday, May 30, 2009

Color Calibration Confusion - Temperature Rising

Some of the readers from Highdefjunkies Forum had questions about my recommendation for temperature settings for calibration. 

I state in the WOWVision! text:

"Temperature - Use the "Low" or "Cool" or 6500K setting - or whichever setting is opposite of warm." Yes, opposite.

I will attempt to explain the relationship between 65K/6500 Kelvin and the "Cool" temperature setting on the television. Perhaps I could bring some "light" to the subject  in what I will call:

Why is the temperature of a WARM white light 2000 degrees COOLER than a COOL white light?

I am attaching a couple of light temperature charts that should shed some lig...that should be very helpful in this exploration. 

Here is a part of the problem. We have two conflicting arenas for description, and even two seemingly "contradictory" sets of terms to describe light. We describe light by its color, by it's temperature, and by its "feel". 

To illustrate this, let's consider fluorescent light bulbs. We have fluorescents that are termed "Warm White" and "Cool white" and also, "Daylight". 

"Warm white" fluorescents are found in rooms and places where you desire a "warm emotional atmosphere". They are generally dimmer than the others and they emit a more red spectrum of light. This light is considered to "feel" warm. Red as a color is described intuitively, as warm. The red coals of your fire are around 2100K. They glow with a red light, and the coals are cozy and warm. We attribute the "feeling" of warmth, to the color red. When the quality of this light is quantified on the Kelvin scale, it has a Kelvin temperature of around 2100k. (Kelvin temperature scale refers to the light emission of a black body heated to a specific degree, like a charcoal briquette that glows red.)

The cool white lamps are what is most commonly found in fluorescent fixtures today. Without a trained eye or a side-by-side comparison, these lamps are perceived as white, thus the white of "Cool white". Cool white's color emissions, however, are in the yellow visible spectrum and the lights are indeed yellow. COOL white registers on the Kelvin scale around 4100k; that's 2000 degrees HOTTER, than WARM white. Cool white emotionally "feels" cooler than the red light. Want a hot room? Paint it red. Cool room? Paint it blue. 

In the last few years it has come to has been found that the yellow "Cool white" fluorescents cause eyestrain, computer screen glare, and mood swings, ushering in the days of the Daylight fluorescents.

What is so special about the Daylight bulbs? "Special" is called "Full Spectrum" in lighting or light. These lights emit THE spectrum where WHITE light resides. These lamps give you vibrant colors in a store, and make everything look cleaner. They are also good for your health (complete like sunlight), used to treat bilirubin deficiencies and depression. These are one type of lamp used in color matching and they are also great for use as grow lamps! (Settle down out there!) And guess what? They come in at 6500 on the Kelvin scale. These are truly the white lights because for something to emit the "color" white in light, all of the colors of the spectrum have to be there, because white light is comprised of all of the colors. (Don't confuse this color mixing in light with painting or pigment! In pigments, the opposite is true. Gee that helps, too.) 

The reason why Daylight bulbs produce the most vivid color, is that all of the colors of the palette are available in white light. The reason why 6500k is desirable in a television is exactly the same. 

Now reference the color charts and take a look at how the mix of terms and temperatures clash. 

Now add the television manufacturer's who can't or won't standardize a remote control, user menu, or even the same term for the 

"aspect ratio/format/ZOOM/Picture" button. Did I miss any? 

Anyway, some manufacturers use LOW/MEDIUM/WARM, some use COOL/NORMAL/WARM, and there are still others. (We'll find out soon enough.) 

To refer once again to the lighting situation, why does the warm white fluorescent lamp produce a redder room, and why does a cool white lamp produce a yellower room? Because they lack the parts of the spectrum to produce white, in other words, they don't have all of the colors available to produce white. 

What if you use the "warm" temperature setting like everyone else recommends? 

I believe that within the calibration world there is a bit of unintentional confusion on this one. That would explain why EVERY television is "hot" on the red. 

One thing I am certain of is this: It doesn't take a week to see a great picture, or WOWVision! would have been named, "Call-you-in-a-week-Vision!"

1 comment:

  1. Wonderful blog & good post.Its really helpful for me, awaiting for more new post. Keep Blogging!