Color notes - references, links, and unsorted stuff: Difference between revisions
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You could argue that the | You could argue that the amount of rods says you should be able to get up to ''hundreds'' of megapixels. | ||
They won't all be | They won't all be firing at the same time, though, but maybe still 100MP, optimistically? | ||
A little more practically, the optic nerve carries maybe a million things, arguing for roughly 1MP. | A little more practically, the optic nerve carries maybe a million things, arguing for roughly 1MP.[citation needed] | ||
And we've been shown to distinguish what roughly translates to ~1MP in the fovea[citation needed] | |||
The thing is that this is not a simple, uniform, linear system (like image sensors are, for reasons of physics, and the sanity of everyone that has to deal with them). | The thing is that this is not a simple, uniform, linear system (like image sensors are, for reasons of physics, and the sanity of everyone that has to deal with them). | ||
So a more practical 'what do experiments show that we can distinguish' angular resolution is around 1 arcminute, and that's ''only'' in the fovea -- which covers roughly 10 degrees of your vision (...roughly, it's a falloff). | In fact, one of the reasons we saccade all over the place while looking is that only the fovea has good resolution | ||
So a more practical 'what do experiments show that we can distinguish' angular resolution is around 1 arcminute, and that's ''only'' in the fovea -- which covers roughly 10 degrees of your vision (...roughly, it's a falloff; the best vision is in a tighter peak, maybe less than 3 degrees?{{verify}}). | |||
So if you count the sharpness of what you are looking at directly, | So if you count the sharpness of what you are looking at ''directly'', it's only on the order of single megapixels. | ||
it's only on the order of single megapixels | |||
Both color ''and'' resolution is ''worse'' in the periphery. | |||
https://en.wikipedia.org/wiki/Peripheral_vision | https://en.wikipedia.org/wiki/Peripheral_vision | ||
https://en.wikipedia.org/wiki/Fovea_centralis | https://en.wikipedia.org/wiki/Fovea_centralis | ||
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Also, "RGB" is not actually a color space -- the best choice depends mostly on the flavour of RGB colorspace you have. | |||
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You could use a simple weighed average, like | You could use a simple weighed average, like | ||
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It can also depend on | It can also depend on specific wishes. | ||
Consider how photographers sometimes use specific colored lenses (or nearly-equivalent photoshop filters) | Consider how photographers sometimes use specific colored lenses (or nearly-equivalent photoshop filters) for specific effects, | ||
for specific effects, such as lessening the visibility of freckles, making skies more contrasted, and such. | such as lessening the visibility of freckles, making skies more contrasted, and such. | ||
===Undetailed so far=== | ===Undetailed so far=== |
Latest revision as of 18:48, 22 April 2024
"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
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
- http://www.poynton.com/notes/events/20031021_LAX_ETC.html
- http://www.poynton.com/PDFs/ColorFAQ.pdf
- http://www.vision.ee.ethz.ch/~cvcourse/brechbuehler/mirror/color/GammaFAQ.html
CIE stuff
Illuminants
Psycho-ish
Formulae
Other
Websites
Online calculators
Color pickers
Color pickers / color schemes / color coordination, often for styles
- http://www.degraeve.com/color-palette/ bases colors on image
- http://pourpre.com/colordb/?i=c486A95&l=eng - harmonies and such
- http://www.telecable.es/personales/alberto9/color/index.htm - funky flash app
Social scheming
Reference lists
- http://fugal.net/vim/rgbtxt.html - color name list
Usability
(considering color blindness and such):
Other/unsorted
More links: http://www.tlbox.com/web_designers/color