Projective Alpha Colour

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dc.contributor.authorWillis, Philipen_US
dc.date.accessioned2015-02-21T14:31:57Z
dc.date.available2015-02-21T14:31:57Z
dc.date.issued2006en_US
dc.description.abstractAlpha colours were introduced for image compositing, using a pixel coverage model. Algebraically they resemble homogeneous coordinates, widely used in projective geometry calculations. We show why this is the case. This allows us to extend alpha beyond compositing, to all colour calculations regardless of whether pixels are involved and without the need for a coverage model. Our approach includes multi-channel spectral calculations and removes the need for 7 channel and 6 channel alpha colour operations. It provides a unified explanation of pre-multiplied and non pre-multiplied colours, including negative coordinates and infinite points in colour space. It permits filter and illumination operations. It unifies the three existing significant compositing models in a single framework. It achieves this with a physically-plausible energy basis.Keywords: projective geometry, homogeneous coordinates, image compositing, alpha blending, alpha compositing, colour representation, filtering, spectral colour, projective alpha colouren_US
dc.description.number3en_US
dc.description.seriesinformationComputer Graphics Forumen_US
dc.description.volume25en_US
dc.identifier.doi10.1111/j.1467-8659.2006.00975.xen_US
dc.identifier.issn1467-8659en_US
dc.identifier.pages557-566en_US
dc.identifier.urihttps://doi.org/10.1111/j.1467-8659.2006.00975.xen_US
dc.publisherThe Eurographics Association and Blackwell Publishing, Incen_US
dc.titleProjective Alpha Colouren_US
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