Halvfärg

Halvfärg, commonly translated as halftone, is a printing technique that reproduces images using a limited number of colors by transforming continuous tonal values into a mosaic of small dots. In a halftone image, brightness is encoded by dot size, spacing, and sometimes shape; from typical viewing distances the eye blends the pattern into perceived tones.

Traditional halftoning relies on screening: the original image is converted through a fine grid to produce a dot pattern that is applied to a print, often as grayscale or color separations. In color printing, separate halftone screens are used for each color component (typically cyan, magenta, yellow, and black), with different screen angles chosen to reduce moiré and to achieve faithful color reproduction.

Digital and modern printing extend halftoning with dithering, thresholding, or error-diffusion to convert images into dot-based representations suitable for printers and displays. The choice of resolution (dots per inch or lines per inch in screening) and dot gain influence tonal range and sharpness. Screening methods include amplitude-modulated halftones (varying dot size) and frequency-modulated or stochastic screening (varying dot frequency or using random patterns) to control texture and pattern visibility.

Halvfärg remains fundamental in offset printing, newspapers, magazines, and consumer imaging due to its efficiency and compatibility with standard press workflows. Limitations include visible dot patterns at close inspection and potential color misregistration if alignment is poor. The term halvfärg is used in Scandinavian languages to denote the same concept as halftone.