Another question, How can I mathematically convert RGB to CMYK? Theoreically it's 1- RGB, but what about K value?
LZ --- "Beer, Christian" <[EMAIL PROTECTED]> wrote: > > I think CMYK support in tools used early in the > publishing chain > > is somewhat overrated. > > Right, but FOP _MUST_ not be early in the publishing > chain! It could > in fact be the only and therefore even the last step > in a publishing > chain... > > > > I can only think of the following use cases for > XSLFO: > > - Avoid round-off errors and other numerical > problems in the > > conversion CMYK->sRGB->CMYK, perhaps in order to > match exactly > > colors of embedded CMYK bitmap images in text, > borders and > > background. > > Conversion CMYK -> RGB is nearly always lossy. And > for print sRGB > is also not that perfect (because of it's small > gammut (nearly the > smalest gammut of all RGB colorspaces)). > > > > - Get color values into the document which can't > be expressed > > as RGB. I don't know whether this can even > happen. > > If you create PDFs for print, you nearly always want > CMYK! Okay, > RGB and colorspace would be great but nowaday not > all print- > companys now how to handle colorspaces (for example > PDF/X-3). > > > > > > As far as round-off goes, AFAIK the transformation > from CMYK to > > RGB and vice versa is linear and numerically well > behaved with > > the exception of some extreme saturated colors, in > particular > > very dark colors. I've never heard of anyone > noticing these > > kind of problem without deliberately using a > somewhat braindamaged > > tool for colorspace conversion which rounded all > values to two > > significant digits *and* both a quite expensive > printing kit and > > a well trained eye. > > 100% c 83% c > 0% m 5% m > 0% y --> sRGB --> 2% y > 0% k 0% k > > So in fact, CMYK -> sRGB -> CMYK is not linear. If > you convert the > result to sRGB and again back the values will even > be more bad. > > > > > J.Pietschmann > > > > > > Christian Beer > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: > [EMAIL PROTECTED] > For additional commands, e-mail: > [EMAIL PROTECTED] > __________________________________ Do you Yahoo!? The New Yahoo! Shopping - with improved product search http://shopping.yahoo.com --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
