Color notes - references, links, and unsorted stuff

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The physical and human spects dealing with audio, video, and images

Vision and color perception: objectively describing color · the eyes and the brain · physics, numbers, and (non)linearity · color spaces · references, links, and unsorted stuff

Image: file formats · noise reduction · halftoning, dithering · illuminant correction · Image descriptors · Reverse image search · image feature and contour detection · OCR · Image - unsorted

Video: file format notes · video encoding notes · On display speed · Screen tearing and vsync

Simpler display types · Video display notes · Display DIY
Subtitle format notes


Audio physics and physiology: Sound physics and some human psychoacoustics · Descriptions used for sound and music

Noise stuff: Stray signals and noise · sound-related noise names · electronic non-coupled noise names · electronic coupled noise · ground loop · strategies to avoid coupled noise · Sampling, reproduction, and transmission distortions · (tape) noise reduction


Digital sound and processing: capture, storage, reproduction · on APIs (and latency) · programming and codecs · some glossary · Audio and signal processing - unsorted stuff

Music electronics: device voltage and impedance, audio and otherwise · amps and speakers · basic audio hacks · Simple ADCs and DACs · digital audio · multichannel and surround
On the stage side: microphones · studio and stage notes · Effects · sync


Electronic music:

Electronic music - musical and technical terms
MIDI ·
Some history, ways of making noises
Gaming synth ·
VCO, LFO, DCO, DDS notes
microcontroller synth
Modular synth (eurorack, mostly):
sync · power supply · formats (physical, interconnects)
DIY
physical
Electrical components, small building blocks
Learning from existing devices
Electronic music - modular - DIY


DAW: Ableton notes · MuLab notes · Mainstage notes


Unsorted: Visuals DIY · Signal analysis, modeling, processing (some audio, some more generic) · Music fingerprinting and identification

For more, see Category:Audio, video, images

"What's the resolution of the human eye?"

Unsorted

http://en.wikipedia.org/wiki/Deep_Color

http://en.wikipedia.org/wiki/XvYCC

Grayscale conversion from RGB

✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

The easiest conversion to grayscale is a simple average, (r+g+b)/3, but this is not very perception-accurate.


There are various RGB standards that mention grayscale conversion as weighing of the channels. In some cases this is based on perception, in some it correction for RGB primaries used in the standard (probably based on phosphors?).

These include:

  • ITU-601-1 and a few others use nearly identical numbers, 0.298954*R + 0.586434*G + 0.114612*B (apparently originating from CIE-XYZ 1931(verify))
  • EBU/ITU 3213 (PAL(verify))): 0.222*R + 0.707*G + 0.071*B
  • BT/ITU-709 (NTSC(verify))): 0.213*R + 0.715*G + 0.072*B
  • ...more


Also, "RGB" is not actually a color space -- the best choice depends mostly on the flavour of RGB colorspace you have.

It can also depend on specific wishes. Consider how photographers sometimes use specific colored lenses (or nearly-equivalent photoshop filters) for specific effects, such as lessening the visibility of freckles, making skies more contrasted, and such.

Undetailed so far

Mostly colour spaces, colour models, and transforms. Again, these are not necessarily accurate.

  • HSV, HSB, HSL/HLS, HSI - hue, saturation, and brightness/level/luminisity/intensity. * IHS,
  • NTSC YIQ, NTSC CMY
  • YUV, YIQ, YCbCr
  • CMY, CMYK
  • HMMD
  • StW, I1I2I3
  • Retinal Cone
  • Munsell
  • Karhonen-Loeve

And things I've read about them:

  • NTSC RGB seems to refer to the defined conversion from YIQ to RGB inside the TV.
  • SMPTE RGB apparently does the same but matches modern phosphors better.
  • IHS conversions seems inconsistently defined between books.
  • I1I2I3 is defined from an (unspecified?) RGB as I1=(R+G+B)/3, I2=(R-B)/2, I3=(2G-R-B)/4, so seems to be a luminance-and-opposite type of system.
  • CIE L*a*b* apparently agrees with Munsell's colour system well.


File format notes:

  • GIF stores RGB
  • JPG stores RGB, YCbCr, or CMYK (verify)
  • PNG is RGB (sRGB unless it stores an ICC profile)


http://color-management-swicki.eurekster.com/device+independent+color+space/


Web gamma: http://hsivonen.iki.fi/png-gamma/

http://www.libpng.org/pub/png/png-gammatest.html

http://www.libpng.org/pub/png/png-colortest.html

References and other links

Technical

General


CIE stuff


Illuminants


Psycho-ish


Formulae


Other



Websites

Online calculators

Color pickers

Color pickers / color schemes / color coordination, often for styles





Social scheming


Reference lists


Usability

(considering color blindness and such):

Other/unsorted




More links: http://www.tlbox.com/web_designers/color

Software

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