High value pixels dark

Weird!

Unless maybe those values are supposed to be opacity...

Nope, clearly states that the values are for darkness.

The thing that really pisses me off is that i''m gonna write it worng in the exam...

Not engineering related, moved to graphics

Whats an ink?

Is that one of those thinks that exists outside of my computer?


RE: Moved to graphics,
I thought that this was more about the actual application, as apposed to the graphical issues... Thats why I put it where it was.


[edited by - fana on May 26, 2003 10:37:48 AM]

quote:

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Original post by fana
Whats an ink?

Is that one of those thinks that exists outside of my computer?

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As in printing ink. ("ink jet printer").

TV, computer monitors and light in general uses *additive* colours. Red+Blue+Green=White

Colour printing with inks uses *subtractive* colours. i.e. think of mixing paints. Red+Blue+Green=Black (with paint it ends up dark murky brown due to impurities in the pigment).

Paint (or ink etc) covers up/blocks out certain wavelengths of light so "subtracts" those wavelengths from the incoming light. e.g. white light is R+G+B, pure red paint blocks out G and B.

Printing with ink in particular doesn''t use RGB colour space. Instead it uses CYMK colour space [Cyan, Yellow, Magenta, Black], black is used because it''s cheaper than multiple passes of CYM to make black. You''ll often see tester patches on things like boxes of cornflakes to check the separate colour ink passes are in key.

Although not specific to the topic TV doesn''t use RGB as input either, it uses YUV/YCbCr/YIQ (variations on the same thing) - Y is luminance, and the other two axes represent blue and red.


I''d usually expect a physics course to start with light - with plenty of experiments with light boxes and prisms to study the properties of light, THEN an explanation of how/why subtractive things (i.e. most coloured materials) work.

--
Simon O''Connor
Creative Asylum Ltd
www.creative-asylum.com