Infographics / Image Quality

Image processing: unsharp mask, edge enhancement & LUT

A graph of filter gain against spatial frequency. A high-pass (edge-enhancing) filter suppresses low frequencies and boosts high frequencies, giving sharper edges and fine detail but amplifying noise. A low-pass (smoothing) filter passes low frequencies and cuts high frequencies, giving less noise but a blurrier image. Two small panels show the resulting image effects.

Spatial-frequency filtering: high-pass sharpening versus low-pass smoothing A graph of filter gain against spatial frequency. A high-pass (edge-enhancing) filter suppresses low frequencies and boosts high frequencies, giving sharper edges and fine detail but amplifying noise. A low-pass (smoothing) filter passes low frequencies and cuts high frequencies, giving less noise but a blurrier image. Two small panels show the resulting image effects. An image splits into spatial frequencies; filters reshape their balance filter gain gain = 1 high-pass boost also amplifies noise high-pass — sharpen low-pass — smooth low frequency large-scale contrast high frequency fine detail, edges, noise increasing spatial frequency high-pass result low-pass result sharper, but noisier less noise, but blurrier
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