Convert Pixels per centimetre to Lines per millimetre

Convert Pixels per centimetre (px/cm) to Lines per millimetre (lp/mm) instantly and accurately.

Conversion Formula

lp/mm = px/cm × 0.1

About Pixels per centimetre

The pixel per centimetre (px/cm) is the metric counterpart of PPI, measuring pixel density per centimetre. EXIF assigns ResolutionUnit = 3 when resolution is stored in px/cm; Canon, Fujifilm, and Nikon cameras can output EXIF data in px/cm. GIMP stores and displays image resolution in px/cm in its XCF format and Image Properties dialog. DICOM (NEMA PS 3.3) stores spatial resolution as PixelSpacing in mm/pixel; a radiograph at 0.2 mm/px = 5 px/mm = 50 px/cm = 127 PPI. At 10×15 cm print size, a 12 MP image (4000×3000 px) prints at 4000/15 ≈ 266.7 px/cm ≈ 677 PPI - well above the ISO 12647-2 minimum of ≈ 118 px/cm (300 PPI). Since 1 inch = 2.54 cm exactly, 1 px/cm = 2.54 PPI exactly. 1 px/cm = 2.54 PPI = 10 px/dm = 100 px/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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