ColorSpace

Happy Birthday Y!

Today Yahoo celebrates 10 years in existance. Kudos to a great company that was instrumental in changing the face of the web !! Cheers and best of luck for the next 10 :D

Colorstrology

I came across this amazing site while I was going through the Pantone online mag. Colorstrology. Amazing Flash intro !! And lots of nifty little things in the site. It talks about your color depending on the day of the year you were born.

Here is my color: Ming  Pantone 15-6120 :D

Generic color spaces

RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. Light is added together to create form from out of the darkness. RGB stores individual values for red, green and blue. RGBA is RGB with an additional channel, alpha, to indicate transparency.

Color spaces based on the RGB model include sRGB, Adobe RGB and Adobe Wide Gamut RGB.

CMYK uses subtractive color mixing used in the printing process, because it describes what kind of inks need to be applied so the light reflected from them produces a given color. One starts with a white canvas, and uses ink to subtract color from white to create an image. CMYK stores ink values for cyan, magenta, yellow and black.

YIQ is used in NTSC (North American) television broadcasts for historical reasons. YIQ stores a luminance value with two chrominance values, corresponding approximately to the amounts of blue and red in the color. It corresponds closely to the YUV scheme used in PAL television except that the YIQ color space is rotated 33° with respect to the YUV color space. The YDbDr scheme used by SECAM television is rotated in another way. (work needed)

YPbPr is a scaled version of YUV. It is most commonly seen in its digital form, YCbCr, used widely in video and image compression schemes such as MPEG and JPEG.

HSV is often used by artists because it is often more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive color components. HSV stores a hue value, a saturation value and an intensity value.

HLS is quite similar to HSV, with lightness replacing intensity value.

Once you've decided which color space you want to work in, if you are working on a computer, you must then address the problem of color space encoding.

Spectral Colors

A spectral color is composed of a single wavelength. For eg. spectral orange has a wavelength of around 600 nm. When we see the emission spectra of certain gases like hydrogen and neon they emit a characterstic spectra which is used in the identification of the gases. This is called electromagnetic spectroscopy.

So what colors are not spectral. Some common examples are white, black and gray. There is no wavelength of light that produces white color. Its just the cummulative result we see when equal amount of light of different wavelengths are reflected completely from a particular object. Black is when no color is reflected from an object. Gray represents the scenario when all the wavelenghts are equally absorebed/reflected by the object. Some other exams are pink, shades of violet, magenta.

Most of the color we see around us is non spectral in nature. Consider your CRT monitor. Its is composed of RGB phospors which combine to give you the 32bit colors. When orange is displayed on your monitor its in not the actual 600nm wavelength that is emitted by the phosphors. Its is a combination of 2parts of red and one part of green which gives you this color.

Why do we interpret both as the same color??
Becoz in the brain, the receptors do not respond to specific wavelengths. They respond to a variety of wavelengths. So lets say when the spectral orange hits the eye it illicits response in the red and the green cones. The response in the green cones is about half the response in the red cones. And the summation of the two responses help in identifying the color as orange. When the cones are stimulated using the mixed color from your CRT lets say a similar respose is generated in the brain again giving rise to the orange color.

The color spectrum

Electromagnetic radiation is a mixture of radiation of different wavelengths and intensities. When this radiation has a wavelength inside the human visibility range (approximately from 380 nm to 740 nm), it is called light. The light's spectrum records each wavelength's intensity. The full spectrum of the incoming radiation from an object determines the visual appearance of that object, including its perceived color. As we will see, there are many more spectra than color sensations; in fact one may formally define a color to be the whole class of spectra which give rise to the same color sensation, although any such definition would vary widely among different species and also somewhat among individuals intraspecifically.

A surface that diffusely reflects all wavelengths equally is perceived as white, while a dull black surface absorbs all wavelengths and does not reflect (for mirror reflection this is different: a proper mirror also reflects all wavelengths equally, but is not perceived as white, while shiny black objects do reflect).

The familiar rainbow spectrum—named from the Latin word for image by Isaac Newton in 1666—contains all those colors that consist of visible light of a single wavelength only, the pure spectral or monochromatic colors.

The frequencies are approximations and given in terahertz (THz). The wavelengths, valid in vacuum, are given in nanometers (nm). A list of other objects of similar size is available.

The color table should not be interpreted as a definite list—the pure spectral colors form a continuous spectrum, and how it is divided into distinct colors is a matter of taste and culture; for example, Newton identified the seven colors red, orange, yellow, green, blue, indigo, and violet, remembered by many school children using mnemonics such as Roy G. Biv and Richard Of York Gave Battle In Vain.

Similarly, the intensity of a spectral color may alter its perception considerably; for example, a low-intensity orange-yellow is brown, and a low-intensity yellow-green is olive-green.

Clothes in the market

International Color Consortium

ICC is the first society in color management

"The International Color Consortium was established in 1993 by eight industry vendors for the purpose of creating, promoting and encouraging the standardization and evolution of an open, vendor-neutral, cross-platform color management system architecture and components. The outcome of this co-operation was the development of the ICC profile specification."

More on ICC

What is color ?

This is one of the most daunting question that poses itself on someone who wants to delve into the science of color. Color is something that is so integral to our lives and the world around us yet it is very difficult to come to a conclusive answer to this question.

While at Adobe I was doing this excersice on Color Management and this question popped up from somewhere and we went about dissecting the matter at hand.

The first thing the need to be realized is the world around us is colorless. There is no color in the universe !!. How cool is that ;-) ?? Its all energy floating around in space. When this energy falls on the cones in the retina it creates a sensation we call COLOR. It exists only in our consciousness, outside which color has no meaning.

Is the shirt your are wearing blue? Are the leaves green? Well there IS no color in the outside world. So you can take your elementry school book that thought you about color and dumb it in the trash. (Well not exactly, they do teach you some really great things like the 3 laws of motion :D ) When they show light falling on a red object and red light coming out of it, it actually dosent happen that ways.

What happens?
The physics:
When light falls on an object its electrons gets excited and move to a higher energy level. When they come back to their ground ( 0 energy ) state they release energy. A lot of this energy is lost until its a true reflector of light. This energy is emitted as photons and photons are the indivisible constituens of any kind of energy, here light energy. The energy emitted determines the wavelength of the light and hence the color response it might elicit in the brain.

The Biology:
Our eyes has receptors called cones that perceive color. There are 3 kinds of them, Reb, Blue and Green. Why these names? Because they respond to light wavelengths in the corresponding wavelengths. When the photons hit the retina in our eyes they activate these cones depending in the wavelength they are in. Lets say a yellow colored (pardon my usage) light would activate the red and the green cones. When the inputs from the red and the green cones are combined higher up in the neural pathway the color we SEE is yellow.

The Metaphysics:
The realization that the seen object is Yellow in color happen in the brain. The colors in the brain are arranged in a somewhat circular manner which was first discovered by Munzel a french painter. He showed that color existed in a circular pattern quite unlike the linear VIBGYOR that we have come to accept. There was a range of colors filling up the gap between Violet and Red which are called transedental colors. These colors do not exist in the light spectrum. Newton was working on something similar after he discovered diffraction, but somehow he gave up this quest of his (more on this sometime later).

So next time you look around yourself just pause for a moment and think... Color ??? Its all in the mind, i say :))