Quoting Bob Johns: > I've supplied a client with digital files 9.67M in size for editorial PR use > in magazines etc. The client wants to use the pics for A3 size posters. I > understand there is a formula that exists that takes into consideration size > of print, dpi etc that you can use to get the file size you need. Is this > correct and does anyone know what that formula is and how it works?
Bob: A number of assumptions would have to be made based on the information you have supplied, however it's possible to give you the basic understanding of what you need to figure out this "math word problem" for yourself. The "conventional wisdom" (which was developed when dealing with scanned images from analog sources ie film) was to use a sampling rate that was 2 times the line screen of the output. I'm more used to "lines per inch" but realize you are probably using "lines per mm or cm" so bear that in mind. A "moderate quality" CMYK output across the pond (ie US) is 150 lpi, which is why so many clients request 300ppi files (2 times 150 lpi = 300). So in the "worst case scenario" your client may expect 300ppi at the final size of the image being used. Then you'll need to figure out from your original (by resizing in photoshop with the "resample" box not checked) whether you have enough original source pixels to get that level of resolution). Don't worry if you don't have that number of pixels, as with digital camera images, less is more. Much depends on the final output paper, glossy paper will show flaws more easily; whereas uncoated papers will forgive a multitude of sins as the ink tends to "bleed" together a bit and cover any minor pixelization. In practice, 1.75 x line screen, or even 1.5 x line screen should be fine. Of course if you don't know what they are using for line screen or papper type you are "shooting in the dark" for the most part, but I would hope you at least have this modicum of info. You don't indicate if the 9.67 m is a measure of "megabytes" (typically abbreviated mb) or megapixels, and/or whether that measure is the size of the file when opened in photoshop as an 8-bit per channel file, or the size of the Jpeg file on your hard drive, so it's impossible to give you much guidance as to whether the files are suitable. FWIW, I would never choose Jpeg as the final storage file type. I might go with the lossless setting of the Jpeg2000, but TIFF seems to be the preferred file format of choice at present. Hope that helps. David -- Creating an image database? visit (http://ControlledVocabulary.com/) and join the discussion list, or read areview of the Image Info Toolkit utility at: (http://ControlledVocabulary.com/imagedatabases/imageinfotoolkit.html) David Riecks http://www.riecks.com - http://zillionbucks.com =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
