function cyl = SensorToCyl(sensor) % cyl = SensorToCyl(sensor) % % Convert from sensor to cylindrical coordinates. % % This is designed for use with the CIE Lxx color % spaces, so it's assumed that the first input % coordinate is luminance and this is taken directly % as height. The next two input coordiantes are % assumed to be chromaticity coords. % % The returned cylindrical system is luminance, radius, angle, % with radius and angle computed in the passed chromaticity plane. % % Note that angle is returned in radians. % % We use the conventions of the CIE Lxx color spaces % for angle. % % See also CylToSensor, SensorToPolar, PolarToSensor. % % 10/17/93 dhb Wrote it by converting CAP C code. % 2/20/94 jms Added single argument case to avoid cData. % 4/5/02 dhb, ly New calling interface. % 11/06/06 dhb No longer allow two passed args. % 1/3/10 dhb Elaborated comments a little. cyl = sensor; cyl(1,:) = sensor(1,:); cyl(2,:) = sqrt( sensor(2,:).^2 + sensor(3,:).^2 ); index = find( sensor(2,:) == 0.0 & sensor(3,:) == 0.0 ); if (~isempty(index) ) cyl(3,index) = zeros(1,length(index)); end index = find( sensor(2,:) == 0.0 & sensor(3,:) > 0.0 ); if (~isempty(index) ) cyl(3,index) = pi/2*ones(1,length(index)); end index = find( sensor(2,:) == 0.0 & sensor(3,:) < 0.0 ); if (~isempty(index) ) cyl(3,index) = 3*pi/2*ones(1,length(index)); end index = find( sensor(2,:) > 0.0 & sensor(3,:) > 0.0 ); if (~isempty(index) ) cyl(3,index) = atan(sensor(3,index) ./ sensor(2,index) ); end index = find( sensor(2,:) > 0.0 & sensor(3,:) < 0.0 ); if (~isempty(index) ) cyl(3,index) = 2*pi*ones(1,length(index)) + ... atan(sensor(3,index) ./ sensor(2,index) ); end index = find( sensor(2,:) < 0.0 & sensor(3,:) > 0.0 ); if (~isempty(index) ) cyl(3,index) = pi*ones(1,length(index)) + ... atan(sensor(3,index) ./ sensor(2,index) ); end index = find( sensor(2,:) < 0.0 & sensor(3,:) < 0.0 ); if (~isempty(index) ) cyl(3,index) = pi*ones(1,length(index)) + ... atan(sensor(3,index) ./ sensor(2,index) ); end