Inspec keywords: edge detection; image colour analysis; image filtering

Other keywords: left-diagonal edges; right-diagonal edges; grey shades; linear colour image filter; quaternion convolution; homogeneous coordinates; colour image pixels; multidirectional colour edge detector; LQS filters; edge direction; single-LQS convolution mask; linear quaternion systems; vertical-diagonal edges; horizontal-diagonal edges

Subjects: Computer vision and image processing techniques; Filtering methods in signal processing; Image recognition