*This article may have affiliate links, which means we may receive commissions if you choose to purchase through links we provide (at no extra cost to you). For more details, please read our privacy policy/affiliate disclosure. Thank you for supporting the work we put into this blog!

Image res­o­lu­tion is the detail an image holds. The term applies to raster dig­i­tal images, film images, and oth­er types of images. High­er res­o­lu­tion means more image detail. Image res­o­lu­tion can be mea­sured in var­i­ous ways. Basi­cal­ly, res­o­lu­tion quan­ti­fies how close lines can be to each oth­er and still be vis­i­bly resolved. Res­o­lu­tion units can be tied to phys­i­cal sizes (e.g. lines per mm, lines per inch), to the over­all size of a pic­ture (lines per pic­ture height, also known sim­ply as lines, TV lines, or TVL), or to angu­lar sub­tenant. Line pairs are often used instead of lines; a line pair com­pris­es a dark line and an adja­cent light line. A line is either a dark line or a light line. A res­o­lu­tion 10 lines per mil­lime­ter means 5 dark lines alter­nat­ing with 5 light lines, or 5 line pairs per mil­lime­ter (5 LP/mm). Pho­to­graph­ic lens and film res­o­lu­tion are most often quot­ed in line pairs per millimeter.