Apparatus and method for transforming a video image into a three dimensional video image with shadows

DETAILED DESCRIPTION The invention provides a video special effects apparatus comprising: (i) transforming means for mapping an input video image onto a three-dimensional surface to Form a transformed image; (ii) luminance level calculating means for calculating luminance levels For parts of said transformed image to produce an effect of a negative light source generating negative light that decreases luminance levels of parts of said transformed image corresponding to parts of said three-dimensional surface where said negative light is incident; and (iii) luminance level control means for controlling luminance levels of parts of said transformed image in dependence upon said calculated luminance levels.
The use of negative light enables shadows to be introduced into a transformed image to create more realistic results, e.
g.
in FIG.
1 a shadow for hump C can be introduced.
In preferred embodiments of the invention said luminance level calculating means is operable to calculate luminance levels for parts of said transformed image to produce an effect of a positive light source generating positive light that increases luminance levels of parts of said transformed image corresponding to parts of said three-dimensional surface where said positive light is incident.
The use of both positive and negative light enables both highlights and shadows to be introduced so as to produce particularly natural looking transformed images.
In preferred embodiments of the invention said luminance level calculating means produces said effect such that, for a point on said three-dimensional surface, said negative light decreases luminance by an amount substantially inversely proportional to distance from said negative lights source to said point.
This preferred feature enhances the realism of the effect by diminishing the decrease in luminance level as the distance between the negative light source and the point in question increases.
The same preferred feature also applies to the positive light source.
Another feature of preferred embodiments of the invention is that said luminance level calculating means produces said effect such that, for a point on said three-dimensional surface, said negative light decreases luminance by an amount substantially proportional to a scalar product of a unit vector normal to said three-dimensional surface at said point and a unit vector of said negative light at said point