Hi everyone. I'm not sure I'm in just the right forum for this question, but I recently had an experience with a print-design project that makes me think I still don't have a proper understanding of color-correction for CMYK images. Actually, I'd love to hear recommendations for a book that covers color-correction procedures with offset printing in mind. I do have Dan Margulis' book "Professional Photoshop" but something more "remedial" might be good for me.
One question that I have is about "total ink values" for the darkest areas of a photograph. What value should I shoot for to ensure a rich, dark shadow without plugging up? I've usually aimed for something close to 300, but I'm wondering what a ideal value is and what other factors influence what that ideal value is, such as anticipated screen ruling. (150 vs 175 lpi, for example) Do different screen rulings require a different total ink value? Is there a matrix available somewhere that gives appropriate total ink targets and takes into account paper, screen ruling, etc.?
Another question I have is about ICC profiles. One print vendor I work with has me assign their ICC profile to all of my images. Doing so is easy enough? but what I don't understand is, doesn't that change alter the shadow and highlight densities that I just got done tweaking? I don't understand what exactly these profiles change in my image. It doesn't make sense to me to do color-correction by aiming at certain ink values and then assign a profile that wipes all of that out. It doesn't quite add up for me, but I suspect it's just that I'm missing some key bit of knowledge.
I'll let those questions get things started? the responses I get are bound to produce more questions, which is good. 'Cuz I need to get a handle on this.
I should say that my background includes shooting half-tones and doing other limited pre-press work back in the days before computers "took over," (in a darkroom with a process camera and litho film, etc) and that I've been doing this work now digitally for almost 11 years. I'm not starting from the ground up, in other words. But I think that somewhere along the line I may have gotten off on the wrong track and I want to make sure I understand things correctly.
Thank you.
TRoutMac
Intelligent (Graphic) Designer
One question that I have is about "total ink values" for the darkest areas of a photograph. What value should I shoot for to ensure a rich, dark shadow without plugging up? I've usually aimed for something close to 300, but I'm wondering what a ideal value is and what other factors influence what that ideal value is, such as anticipated screen ruling. (150 vs 175 lpi, for example) Do different screen rulings require a different total ink value? Is there a matrix available somewhere that gives appropriate total ink targets and takes into account paper, screen ruling, etc.?
Another question I have is about ICC profiles. One print vendor I work with has me assign their ICC profile to all of my images. Doing so is easy enough? but what I don't understand is, doesn't that change alter the shadow and highlight densities that I just got done tweaking? I don't understand what exactly these profiles change in my image. It doesn't make sense to me to do color-correction by aiming at certain ink values and then assign a profile that wipes all of that out. It doesn't quite add up for me, but I suspect it's just that I'm missing some key bit of knowledge.
I'll let those questions get things started? the responses I get are bound to produce more questions, which is good. 'Cuz I need to get a handle on this.
I should say that my background includes shooting half-tones and doing other limited pre-press work back in the days before computers "took over," (in a darkroom with a process camera and litho film, etc) and that I've been doing this work now digitally for almost 11 years. I'm not starting from the ground up, in other words. But I think that somewhere along the line I may have gotten off on the wrong track and I want to make sure I understand things correctly.
Thank you.
TRoutMac
Intelligent (Graphic) Designer