Convert Dots per pica to Lines per millimetre

Convert Dots per pica (dot/pica) to Lines per millimetre (lp/mm) instantly and accurately.

Conversion Formula

lp/mm = dot/pica × 0.2362204724

About Dots per pica

The dot per pica (dot/pica) is a typographic resolution unit linking printer DPI to the pica - exactly 1/6 inch in the PostScript standard (Adobe, 1985). A 72 DPI Macintosh screen placed exactly 12 dots per pica (1 dot per point); a 300 DPI LaserWriter placed 300/6 = 50 dot/pica, providing 50-level halftone cells per pica. High-end digital imagesetter platemakers: Agfa Selectset Avantra 45 at 3600 DPI = 600 dot/pica; modern 2400 DPI proofers produce 400 dot/pica. Desktop publishing software - Adobe InDesign, QuarkXPress, Affinity Publisher - defaults to pica+point rulers (e.g., 4p6 = 4 picas 6 points = 0.75 inch), making dot/pica a natural precision unit for typographic rasterisation quality assessment. 1 dot/pica = 6 DPI = 6 PPI (since 1 pica = 1/6 in). 1 dot/pica = 6 PPI = 15.24 dot/m.

About Lines per millimetre

The line pair per millimetre (lp/mm) is the fundamental unit of spatial resolution in classical optics, characterising the resolving power of a lens, film emulsion, sensor, or microscope objective. A resolving power of N lp/mm means adjacent line pairs separated by 1/(2N) mm can be distinguished - derived from the Abbe diffraction limit (Ernst Abbe, 1873) and Rayleigh criterion (Lord Rayleigh, 1879). Film benchmarks at MTF50: Kodak Tri-X 400: 63 lp/mm; Fujifilm Velvia 50: 160 lp/mm; Kodak Technical Pan: 320 lp/mm. Lens benchmarks: Leica APO-Summicron-M 50 mm f/2 ASPH: ≈ 75 lp/mm at centre. CMOS sensor Nyquist frequency: for pixel pitch p mm, f_Nyquist = 1/(2p) lp/mm - a 4.63 µm pixel limits at ≈ 108 lp/mm. As a dimensional unit, 1 lp/mm = 25.4 LPI = 25.4 PPI exactly. 1 lp/mm = 25.4 PPI.

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