Screen frequency / resolution of plot or line screen I number of printer dots or cells of semitones per inch used to print images in grayscale or color separations. Also known as screen frequency, screen frequency is measured in lines per inch lpi (lines per inch) or lines of cells per inch of a halftone screen. Halftone screen frequency is a specific feature of those images that will be printed, mainly, in a professional device. Also referred to as resolution of plot and refers to the number of halftone cells used to print an image in grayscale or color separation. It is usually measured in lines per inch (lpi) and affects primarily, along with the resolution, the details of a printed image. Let’s try to shed a little light on this tiny but complex concept. A printing device, by much resolution you are, when you have to paint a point (either with ink, toner,..) he paints or paints it not.
I.e., stuffed, or not as fill in, there is no half-measures. But and if we need half measures? Then the problems start. Imagine a figure whose filling we intend to be gray. Our printer must draw the image using a percentage of black, we suppose that it is 50%, then, except that the software that generates the image or the RIP that processes it is told otherwise, it will divide its resolution and will draw 50% of black squares. This is called a halftone screen. Simplify.
You want to print a halftone screen on a device of 2400 dpi with a 150 lpi screen. The machine divided resolution between line-screen ruling (2400: 150 = 16) (e) printed lines of 16 points for each semitone, so it would be able to set 256 gradations of tone. If also specify you that draw the points round, elliptical, square, you diamond,… so you will make it.