From: "3d-doc" <3d-doc@technologist.com> To: <3DSMAX@engram.net> Subject: Pixels and DPI Date: Friday, April 14, 2000 10:08 AM Hi All, I've read with interestthe recent post about printing sizes, and how to convert Pixels to Dpi. Here's what I have been taught : - Pixels have no real-world size. Its only a square (or rectangular) dot filled with one color, this color being coded in RGB values. It's the smallest element in a picture, hence the name. Being a square with one color, its size can easily be adjusted to the required output resolution : the maths behind this are kind of basic ;) -The output resolution depends on the physical characteristics of the output device. Computer Screen : 72 dpi (in general), B&W laser printers 300 dpi, Color printers 720-1200 dpi, professional output devices over 2400 dpi if needed. Basically, if you need to output an image file with a precize output size in inches or centimeters, you must first know the output device's resolution. Mutliplying the output size by the output res gives you the amount of pixels needed. - Therefore, a pixel's size depends on the output resolution. You know these large banners they use for musem exhibitions : the pixels on it are rather large (5 x 5 inches for instance), but the if the same image (say a 640x480 image) was printed on a hi-res printer, you'd end with much smaller pixels : 0.00001x0.00001 inch per poxel.... Actually one shouldn't call it pixels, but dots, because pixels can only be found in computers, since they are numeric and have no particular size... - And when Photoshop resamples your image, it does not resize pixels : it adds pixels, using interpolation methods between color values. - Note that the resoution of a computer monitor varies with the actual size of your display : with a 21", 1024x768, a 283x283 pixels picture will give a 10x10cm image, but it will give a 9x9 cm image using a 17" monitor (1024x768), and a 13x13cm with this same 17" monitor at 640x480. This is because the physical points (hell, I can't remember the name of these) on the tube (CRT) have a fixed size exactly like a jetink printer's head create fixed-size dots. So the 72 dpi rule is only intended to give a general idea. Well I don't know if I'm really sorting the things out here...;hope this helps... :) Have a nice day D3D -- Subscribe/Unsubscribe at: http://mail.engram.net/guest/RemoteListSummary/3DSTUDIOMAX List courtesy of http://www.Engram.net