Monday, May 5, 2014

Color Trek

“P’tak!” shouted the Klingon, as he drove his dagger into the computer monitor, causing a shower of sparks to shoot across the bridge of the starship. “Nga’chuqing pjqlod of a sli-vak!” He proceeded to stomp the remaining bits of advanced computer hardware into tiny pieces, cursing furiously.

Commander Riker, stroking his clean-shaven chin, asked, “Hey Worf! Is something the matter?”

“Stupid Earth technology! VeQ! We almost lost the number 1 core because of that idiotic monitor. Overload conditions are to be displayed in red,” Worf growled, looking both hurt and angry, as if he was personally disrespected, “but that mIghtaHghach display is ambiguous. I can hardly tell a normal condition from abnormal.”

“Well, it looked pretty red to me,” replied Riker, “and I thought that I probably should have mentioned it to you, but you know how you get whenever you are contradicted.” Then he thought to himself, “Maybe I ought to grow a beard. I’d get a lot more respect that way.” Riker, turning to a pale android who seemed to have ignored the recent outburst of violence, asked “Data, any idea what is going on here?”

Lieutenant Commander Data showed his typical puzzled robotic expression. “I wish I could help you,” he replied, “but Ensign Crusher is siphoning off 98.7% of my positronic CPU capacity in order run an otome gēmu simulation. Please wait; process terminating.” [An anguished cry is heard from the other side of the bridge: “Noooooo!”]

“Let me download some pertinent information. OK. Lieutenant Worf, you stated that you were unable to distinguish between overload and normal conditions on the monitor, based on the status color. —All right, by your expression of anger I can assume the affirmative. Commander Riker, you state that the status condition color was red as expected for a core overload condition.” Data nodded seriously. “I think I know what the problem is.”

“Let me demonstrate.” Data randomly selected an image from the starship’s database, displaying it on the forward screen, an image showing Counselor Troi having too much to drink at a party. “Commander Riker, how does this image look to you?” He paused. “Commander Riker?”

“Yeah, she looks really great,” he replied, “Could you put a copy of that in my personal files?”

“Sir, I am asking you about the color rendition of the display. Do the colors look accurate to you?”

“Yes. Fine. Looks great.”

“Lieutenant Worf, how does this image look to you?”

“Like many Earth displays, it is far too bright — and maybe, what? fuzzy?”

“Would you say that the monitor has low contrast? That it does not render black tones well?”

“Yes. Exactly,” replied the Klingon.

“Klingon eyes,” explained Data, “are similar to human eyes in that they have a long-wave class of photon receptors which are generally sensitive to the red part of the spectrum, however, the sensitivity extends into what humans call the invisible ‘infrared’ — but of course, to Klingons, that part of the spectrum is simply ‘red’, indistinguishable from what a human would call red.”

The android continued, “Many Human displays, such as this one, emit a significant amount of uncontrolled infrared radiation, visible to Klingons, but not humans. This both makes the display excessively bright to Klingon eyes, as well as low in contrast. Also, I can assume that all humans, to Klingon eyes, look pale, due to the transparency of human skin to infrared.”

“Yes,” replied Worf, “they all look alike to me.” He addressed Lieutenant Commander La Forge: “But I always recognize you from your VISOR.”

“Lieutenant,” continued Data, “what about the colors on the screen? How do they look to you?”

“They are bad. Wrong. Filthy. I always have a nagging suspicion that humans choose wrong colors because they are weak, decadent aesthetes, or that they are doing that simply to outrage my people.”

“You know that isn’t true. Perhaps you could describe to us the colors of the spectrum? As you see them?”

“Of course. Red, orange, yellow, green, kth’arg, and blue. Every child knows that.”

Kth’arg?” asked Riker. “Not cyan?”

“Yes, kth’arg,” snarled the Klingon. “Yes, cyan is a mixture of green and blue; I know that and I see that. But kth’arg is not cyan. Kth’arg is kth’arg. That photograph up there,” he pointed to the screen, “has colors that ought to be kth’arg but are blue, and are kth’arg instead of green. Things that are orange in real life appear to be red, and things that are yellow are shown as orange.” His hand moved slowly towards his dagger.

“Human eyes,” said Data, “have three general classes of light receptors, notionally identified as being sensitive to red, green, and blue light, or more accurately, to long, medium, and short wavelengths of light respectively. Klingons have a weak fourth class of color receptors which have a peak sensitivity to wavelengths between the ‘green’ and ‘blue’ receptors, which leads to the kth’arg sensation. As such, it is not a translatable or perceivable color to humans. Also, I might note that Klingons, due to the downwardly-shifted sensitivity of their red receptors, are unable to distinguish between blue and spectral violet — they literally are the same color to them.”

“That foul monitor,” said the Klingon, pointing to the pile of smoldering components, “was supposed to display normal condition with a green color, but it looked to me like a orangish kth’arg, while abnormal conditions ought to be shown in red, but instead looked like a kth’argy orange. Those colors are almost identical. If I hadn’t double-checked the core status, we would have all been dishonorably slain by now.”

“Now wait,” replied Riker, “I don’t understand this. Aren’t we using the latest equipment? How can this go wrong?”

“The problem is known as metamerism, where many wavelength combinations are perceived as the same color” replied the android. “My own ocular sensors are multispectral — I can distinguish among many narrow spectral bands of light — but these perform poorly under dim lighting conditions such as we experience here on the bridge, and so my vision module can combine many narrow bands into several large overlapping ones, similar to human vision. This gives me some color distinction while greatly reducing the amount of photonic noise in my sensors. While I have less data to go on, it usually hardly matters, and it greatly reduces the burden on my CPU from vision processing. But what this means is that there is an infinity of combinations of wavelengths that deliver the same perceived color. You might perceive a single wavelength as ‘cyan’, but any number of combinations of blue and green wavelengths will give you the same perception — that is metamerism. As it so happens, that single wavelength you perceive as ‘cyan’ is perceived by Lieutenant Worf as kth’arg, while both you and he both perceive combinations of green and blue as cyan. This is a metamerism failure.”


“Our Federation Standard displays use three primary colors — red, green, and blue — which when mixed together in varying proportions can deliver a significant fraction of all colors seeable by the typical human eye. But don’t forget, there are an infinity of combinations of wavelengths of light that will be perceived — by a human — as the same primary color. The particular green color used in Lieutenant Worf’s late display — to him — appears to be more of a kth’arg color and not green at all. Another display — identical to you — might appear to be quite different to him, simply because the primary colors use a different metameric mix of wavelengths. You see Sir, our displays — with three primary colors — are designed specifically for human vision. A Klingon display needs at least four primary colors — including an infrared component — with a metamerism tailored for Klingon vision.”

“Commander Riker, Sir,” requested Data, “may I suggest that we requisition a Klingon-specific display for Lieutenant Worf’s use.”

[Three months later…]

“So Worf,” said Riker, confidently stroking his new beard, “how is the new display?”

“It is glorious! I shall compose a song praising its beauties.”

“Looks like garbage to me,” laughed the Commander as he walked away.