Hi Terence, grayscale printing to (non proofing) inkjet, thermotransfer or laserprinters depends on custom printerdrivers wich will convert colors to printer-suitable spaces. Most inkjets will support neutral (grayscale) blacks with cyan (or sth equal), and as far as I know most of them will convert any color to RGB first - even if your printer supports cmyk or 6 to 8 (cmyk+) colors. Colorspace does matter here as long your printerdriver is able to recognize it but, as far as I know, most don't?
Proofers are different because they are designed to output profiled prints and more or less direct cmyk. Are these profiles the profiles of the printing machine (paper/ printcolors) you will print on? Does the printshop calibrate there machines to THIS profile? And proofers put out ideal print under ideal circumstances not "real life" mass printing (staying simple here :) OK, the need (?) of neutrality? Print is, under common conditions, profiled or not, tolerant. (with a few exceptions) - you always will have a tolerance of around (or at least of) 5 % in dot sizes. Say if you have sth neutral (wich is isn't?) 40-40-40-0 you might get (depend on printing color, paper, temperature, mood, water, etc) sth like 45-40-45-0 known as sth green within the first 2500 prints - and if the printer is in a bad mood (or is trying to recalibrate her machine), from 2500 to 5000 you will get 40-40-50-0, from 5000-7500 sth like ... so - you will have no guarantee for neutrality. Another reason to use only K for grayscale images is the raster dots. 4 color standard (not modulated) raster dots are created to form circles and will always produce slightly visible moir?s. Though "more" information is provided gray produced out of 3-4 colors seem to be slightly less sharp as if created with only "pure" K (very much depending on raster dot size). One disadvantage using exclusively K is the lack of deep black and therefore contrast. To compensate both disadvantages (lack of neutrality, moir?, lack of contrast) one common way is to support "neutral" colors with a lower percentage of CMY. Say if you want a "neutral" (slightly cyan - which is intended to be recognized as neutral) 90 percent tone you might generate sth like 20-10-10-80 - wich has enough "deepness" and some guarantee to not being printed with too much visible tolerance or too much visible moir?. > You're going to save expensive color pigments (toner/ink). > Depending on your > printer, the print job can be done in one pass instead of 4 (up to > 4 times > faster). You're sure you won't get any color cast... > > In short, your print will be better, faster and cheaper. > > 2007/3/13, Terence Chan <terence at onetel.com>: >> >> Excuse my ignorance but why is it important/deirable to have >> greyscale >> images on the K plate only? I finished a book recently with lots >> of greyscale images colour profiled in RGB/CMYK PDF (set to >> "printer"). >> The page proofs from the printer look just like what I wanted, so >> what's >> wrong with that? >> >> Terence >> >> On Tue, 13 Mar 2007, Vladimir Savic wrote: >> >> > >> > Try! And prove you're wrong! Tested with Acrobar Pro from CS >> creative >> suite. >> > RGB input is not a bad solution at the first place. :) Output is >> color >> > profiled CMYK PDF. (which means that fallowing my procedure, >> finally >> applied >> > color profile will only effect visual appearance of K plate, but >> not >> it's >> > nature - it will be grayscale (that is K only), not composite >> grayscale.) >> > >> > BTW, I'm running linux, so I don't have anything other then The >> GIMP to >> work >> > with. Using PS on win boxes is much faster/natural way to make CMYK >> images >> > without that much pain, but never tried it... :( >> > >> > Vlada >> > >> > > Setting the image to CMYK does work for me. I don't know wich >> app you >> > > use but if you convert >> > > your image to CMYK you should make sure you delete all data >> from the >> > > CMY channels and copy the original >> > > K or Grayscale data only to K or try "maximum Black" >> conversion mode >> > > (before you import them) >> > > >> > > Jon >> > > >> > > Am 12.03.2007 um 12:54 schrieb Vladimir Savic: >> > > > On Monday 12 March 2007 17:43:36 Terence Chan wrote: >> > > >> Yes, I believe this is normal behaviour for scribus - why >> is this >> > > >> a problem? So long as you apply the appropriate icc input and >> output >> > > >> profiles the greyscale images should appear ok when printed >> and on >> > > >> the screen. >> > > >> >> > > >> Terence >> > > > >> > > > Hmmm... >> > > > I was doing something obviously wrong here too (talking about >> > > > Scribus 1.3.3.x >> > > > not 1.3.4cvs). "Appropriate profile" is a key point. No >> profile can >> > > > ensure >> > > > grayscale RGB (picture in RGB color space but completely >> > > > constructed of r=g=b >> > > > values pixels) picture to appear on K plate only when PDF gets >> > > > token to >> > > > prepress office. >> > > > Right approach would be to ask of user if imported picture is >> > > > composite >> > > > grayscale picture or single color channel image. >> Fortunately, in >> > > > 1.3.4 there >> > > > is a simple solution: image effects -> apply colorize image and >> > > > give that >> > > > picture 'black' color colorization (Don't take further >> writing for >> > > > granted >> > > > but I think choosing 0%C 0%M 0%Y 100%K "in-Screibus hand made" >> > > > color doesn't >> > > > work correctly) >> > > > >> > > > Vlada >> > > > >> > > >> On Sun, 11 Mar 2007, Lila Pagola wrote: >> > > >>> hi! >> > > >>> I'm working with Scribus in a book, almost finished, >> because we >> > > >>> are in >> > > >>> press with everything except cover. >> > > >>> >> > > >>> Preparing the cover design for pre-press (I don't if in >> english >> > > >>> it's said >> > > >>> that way), I have found a rare behavoir of Scribus with >> grayscale >> > > >>> images: >> > > >>> they are considered as RGB files, in any format I try to >> import >> them >> > > >>> (PNG8, gif, tif). And If I import them as CMYK I have >> information >> > > >>> in the >> > > >>> 4 channels when the image is just black. >> > > >>> >> > > >>> Somebody has experiencied something similar? Am I doing >> something >> > > >>> wrong? >> > > >>> I did a quick search on the web and the list's archives and I >> > > >>> didn't find >> > > >>> any report of this problem. >> > > >>> >> > > >>> Our project has a wiki when we are uploading the problems and >> > > >>> solutions >> > > >>> we found, in spanish, sorry (and for my english sorry too) >> > > >>> the url is http://nomade.liminar.com.ar/wakka.php?wakka=MaBI >> > > >>> >> > > >>> Thanks in advance for any clue ... >> > >> > _______________________________________________ >> > Scribus mailing list >> > Scribus at nashi.altmuehlnet.de >> > http://nashi.altmuehlnet.de/mailman/listinfo/scribus >> > >> >> >> _______________________________________________ >> Scribus mailing list >> Scribus at nashi.altmuehlnet.de >> http://nashi.altmuehlnet.de/mailman/listinfo/scribus >> > _______________________________________________ > Scribus mailing list > Scribus at nashi.altmuehlnet.de > http://nashi.altmuehlnet.de/mailman/listinfo/scribus
