kleurfringing

Kleurfringing, literally “color fringe” in Dutch, is a form of chromatic aberration observed in optical systems, particularly cameras and lenses, where high-contrast edges display colored halos or outlines. It arises because optical lenses refract different wavelengths of light by different amounts (dispersion), so colors do not converge at the same focal point.

Two main types exist. Axial (longitudinal) chromatic aberration occurs when colors remain in focus at different distances from the lens, producing fringes that vary with focus and appear in out-of-focus regions. Lateral chromatic aberration occurs when colors diverge across the image field, causing fringes that run along edges and become more pronounced toward the frame borders.

Mitigation strategies include advanced lens design and digital correction. Achromatic and apochromatic lenses are engineered to bring specific wavelengths into closer agreement, reducing axial CA. Stopping down the aperture often minimizes it further. Digital corrections, using lens profiles or software, can align color channels to reduce fringes after capture. In some sensors and demosaicing processes, purple fringing may appear near bright highlights, which may also be addressed in post-processing. However, aggressive corrections can trade fringe reduction for loss of fine detail.

Kleurfringing affects perceived sharpness and color accuracy, particularly in high-contrast scenes or with wide apertures. It is a common consideration in photography, microscopy, and other imaging disciplines, with ongoing optical and algorithmic approaches aimed at minimizing its impact across devices.