On Saturday 08 August 2009 04:54:09 pm Hal V. Engel wrote: > On Saturday 08 August 2009 12:07:59 pm John Culleton wrote: > > On Saturday 08 August 2009 11:58:40 am Gregory Pittman wrote: > > > On 08/08/2009 11:57 AM, John Culleton wrote: > > > > On Friday 07 August 2009 07:19:29 pm John Culleton wrote: > > > >> LSI is enforcing a rule that total ink coverage of any > > > >> CMYK color cannot exceed 240% The usual example is rich > > > >> black. > > > >> > > > >> 1. Can this be a problem in Scribus? > > > >> 2. If so, how does one detect/fix such overcolored areas? > > > >> > > > >> I presume that none of the standard colors exceed this > > > >> limit. But I worry about graphics from e.g., Gimp which > > > >> are RGB converted to CMYK when Scribus writes the file. > > > > > > > > To further illuminate the question, these are the > > > > recommended values whan using Photoshop: > > > > ------------------------ > > > > Engine: Adobe (ACE) > > > > Intent: Relative Colorimetric > > > > Use Black Point Compensation: Yes > > > > Use Dither: Yes > > > > ------------------------------- > > > > and > > > > ----------------------------------- > > > > Ink Colors: SWOP (Newsprint) > > > > Dot Gain: 25% > > > > Separation Type: GCR > > > > Black Generation: Medium > > > > Black Ink Limit: 100% > > > > Total Ink Limit: 240% > > > > UCA Amount: 0% > > > > ------------------------------- > > > > for the custom CMYK settings. > > > > > > > > Perhaps there is an ICC profile that can take care of all > > > > this. > > > > > > I don't know that there are any color sets that come with > > > Scribus that will exceed this. Of course, we get some list > > > questions from some who think that they want all the CMYK > > > saturated, but obviously don't understand the printing issue. > > > > > > What it does suggest, though, is that one of the things the > > > Preflight Verifier could do would be to check for ink limits. > > > Maybe you could file an RFE. > > > > > > Not sure how they might imagine someone specifying > 100% > > > Black...seems that would be kicked out by the printing > > > equipment. > > > > > > Greg > > > > > > _______________________________________________ > > > scribus mailing list > > > scribus at lists.scribus.info > > > http://lists.scribus.info/mailman/listinfo/scribus > > > > Consider the image from Gimp that has black on it. That is RGB > > 0 0 0. What would Scribus change it to in CMYK? > > There seems to be some misconceptions here. CMYK is a > subtractive color space so higher values mean more ink (if you > are talking about a printer). The K ink in a CMYK system is used > as a substitute for higher levels of process gray (C = M = Y) to > create darker tones and reduce ink load for the same darkness. > Many printer/ink/paper combinations can handle total ink levels > much higher than the 240% talked about above but some can not and > some can not handle even 240%. > > The darkest blacks on most printers are a combination of K plus C > and M (sometimes called rich black). In addition on many modern > ink jet printers the "black" ink has a yellow tint that is > intended to allow these very dark blacks without causing a hue > shift because of the added C and M ink (IE. to keep the resultant > black neutral). The normal operation for these printers is to > always mix some C and M ink with the K ink to shift the hue > toward neutral even for lighter grays although for the very > lightest grays this may not be needed because the white point > will be shifted toward blue (IE. away from yellow) because of the > "whiteners" used in many papers. > > All of this is very device specific, meaning specific to a > printer/paper/ink/work flow, and the only way to insure that you > are doing the right CMYK separation for your device is to use the > correct ICC profile for the device in question. These profiles > will have an optimized GCR setup and also have proper ink limits > so that there is no over inking and there are proper transitions > to the K ink as well as proper use of C and M inks to keep grays > and blacks neutral. > > Hal > > _______________________________________________ > scribus mailing list > scribus at lists.scribus.info > http://lists.scribus.info/mailman/listinfo/scribus
LSI wants the SWOP profile but also enforces the 240% rule for cover files. They have an ink and paper combo that requires this limit. The usual way to make sure that their specs are met is through Photoshop. I am looking for a Scribus way. -- John Culleton Create Book Covers with Scribus/e-book $5.95 http://www.booklocker.com/books/4055.html
