thereby appear first (or at least nearer the top) in drop-down lists. This is helpful if there are alot of profiles in the default (system) area.
Dan Dill
"It is a magical time. I am reluctant to leave. Yet the shooting becomes more difficult, the path back grows black as it is without this last light. I don't do it anymore unless my husband is with me, as I am still afraid of the dark, smile.
This was truly last light, my legs were tired, my husband could no longer read and was anxious to leave, but the magic and I, we lingered........" Ginger Jones
... the trick of using the K channel as a mask for LAB moves. These days, I use it inverted to blur the shadow noise in high ISO images. I use it blurred (and not inverted) to limit sharpening to midtones and highlights in high ISO images. I use it inverted to target a curve layer to the shadows, something that is nearly always a good idea.
Thanks for that "high bandwidth" series of remarks. I look forward to trying each of these suggestions.
Dan Dill
"It is a magical time. I am reluctant to leave. Yet the shooting becomes more difficult, the path back grows black as it is without this last light. I don't do it anymore unless my husband is with me, as I am still afraid of the dark, smile.
This was truly last light, my legs were tired, my husband could no longer read and was anxious to leave, but the magic and I, we lingered........" Ginger Jones
For personal reasons (maybe the constant headache or maybe that I don't envision needing CMYK output - not sure), I'm having trouble getting too far into the detail of this chapter.
I understand that for neutral the C value must be a few point higher than the M & Y values.
I understand that you can save some overall % total by reducing CM & Y somewhat and increasing K about the same (possibly slightly less of an increase).
I understand that by doing this a bit less ink is thrown at the paper.
Now, to simplify my question.
If I reduce CM & Y by let's say 15% and increase K by about 15%, what actual effect will that have on the colors of the image?
Again, thanks for the great writeup.
(Unrelated- For those interested, I posted, at the end of the Chapter 4 thread, some tricks I learned that helped me complete the quiz on Page 84)
If I reduce CM & Y by let's say 15% and increase K by about 15%, what actual effect will that have on the colors of the image?
If you do a general, global move, you will destroy your image. Not good. The downside with CMYK is that you have to concern yourself with questions like this, regarding your shadows. The upside is, it's much easier to target blacks since they actually exist as a separate entity, rather than being rolled up in the color channels. So you'll need to restrict your move to the shadows.
Dan suggests using Selective Color, set to Black. Pulling C, M, and Y down by as much as 15% would constitute a fairly drastic shift, but, in theory, replacing it with equal black should accomplish the task.
But not really. those C, M and Y values are pulled from the featureless smudge that constitutes most shadow areas in the color plates, whereas the added blacks contain all the shadow detail. So indiscriminently pouring black on top of itself will probably ruin the shadows. That's why you use a curve in the black channel instead. Unlike other color tools, curves can be precise in the range that they target. In your black plate, you are, of necessity, dealing with a narrow range of detail. A curve allows you to pull the range proportionately, darkening the darkest parts, while retaining some distinction in the lighter areas, retaining detail.
Before Selective Color came along, the trick was to use the black plate as a selection, or a layer mask for a Curve adjustment layer, a trick that I still apply in other spaces. Also, as Rutt pointed out in this same thread, CMYK can be the place to go for any kind of serious shadow work, even if the image will end up in a different space.
There are two ways to slide through life: to believe everything or to doubt everything; both save us from thinking.
—Korzybski
CMYK profiles
Ok, first ever post to the Digital Grin forum. "Oh Lord please don't let me make a fool of myself".
On to my question. In the situation where I inhabit an entirely RGB based workflow, but I want to make use of the CMYK space for all the usual good reasons of channel mixing etc, why would I create a CMYK profile that reflects the limitations of ink and paper. Could I set the total ink limit to 400% for example? Dot gain to 0%? Does it make any difference with such a workflow?
Ok, first ever post to the Digital Grin forum. "Oh Lord please don't let me make a fool of myself".
On to my question. In the situation where I inhabit an entirely RGB based workflow, but I want to make use of the CMYK space for all the usual good reasons of channel mixing etc, why would I create a CMYK profile that reflects the limitations of ink and paper. Could I set the total ink limit to 400% for example? Dot gain to 0%? Does it make any difference with such a workflow?
Welcome to Dgrin and congrats on your first post!
Well, if I understand you correctly... If you're are NOT going to actually use CMYK as your final colorspace and simply want to do some color corrections there with the intention to go back to RGB (or continue to LAB), there is nothing that should stop you from doing all those things you've mentioned, and then some. It's simply a different set of formulas and rules. If it helps you get the results you want faster - sure, why not!
In the situation where I inhabit an entirely RGB based workflow, but I want to make use of the CMYK space for all the usual good reasons of channel mixing etc, why would I create a CMYK profile that reflects the limitations of ink and paper. Could I set the total ink limit to 400% for example? Dot gain to 0%? Does it make any difference with such a workflow?
There are a couple of profiles on the included disk for this very purpose.
One is rgbk, the other is wgcmyk. They have an extended cmyk gamut. They allow you to convert from rgb to cmyk and back about as lossless as possible.
Because they don't reflect the limitations of ink and paper they are not meant to be used for output to press.
They have subtle differences. One works better on some images and vice versa.
Regards,
Michael
Michael D. Aery, KSC | Prepress Manager
Graphics23 - Design, Illustration, Restoration & Retouching
What's a Pirate's favorite color mode? Arrrr, G, B!
Ok, first ever post to the Digital Grin forum. "Oh Lord please don't let me make a fool of myself".
On to my question. In the situation where I inhabit an entirely RGB based workflow, but I want to make use of the CMYK space for all the usual good reasons of channel mixing etc, why would I create a CMYK profile that reflects the limitations of ink and paper. Could I set the total ink limit to 400% for example? Dot gain to 0%? Does it make any difference with such a workflow?
Good question. In a sense, that's exactly the situation that I dealt with when I wrote this chapter summary: all my samples were prepared with an eye to demonstrating a CMYK workflow, but, since they were destined for the web, they ultimately wound up in RGB. And they were the better for having been prepared with Dan's specifications.
It's true that you're not really worrying about ink, but if you were to pop your image into CMYK using, say, a max black setting, you would find it impossible to make the kind of shadow moves that are possible using Dan's separation specs. CMYK is simply a better space for shadow work, and the benefits translate back to RGB once you're done. You just need to be real clear about your needs. Not all images require a CMYK move, and for the ones that do, not all separations are equal.
If the issues are color oriented, rather than shadow detail, CMYK can be a mixed bag of results. If your image is heavy with pastels and bright oranges, greens and blues, an ordinary move into CMYK will ruin it. The profiles Micheal mentions could be useful in those cases. (But, then, if you have a pastel-laden image, you might not want a CMYK move at all.) But I find skin tones to be much easier to fine tune in CMYK due to the lack of shadows in the crucial areas of the skin range. In RGB, the curves can rapidly get out of control pretty easily, particularly in the shadow. And the reduced color gamut can work to your advantage. Sometimes I find skin tones that have a day-glo, neon sheen to them, tones that get safely muted and desaturated in CMYK (although that's far from a precise approach.) But sometimes it works. Also, the dot-gain compensation that CMYK conversions perform can offer some work arounds. If your skin tones are too hot, you can get interesting results by making a copy of your Red plate, then converting to CMYK and substituting the original Red for the new Cyan. If you do this in a duplicate layer, peel back the shadows with Blend-if sliders and adjust opacity to taste, you get an boost in real cyan tones rather than the purple hues that result from simply blending magenta into the cyan plate.
So, when should you go into CMYK? Like Dan says, "It depends."
There are two ways to slide through life: to believe everything or to doubt everything; both save us from thinking.
—Korzybski
Well many thanks to all those who responded to my original post, they were right on the money. I am very impressed with the quality of input to this forum so thank you for your time.
Comments
C:\Program Files\Common Files\Adobe\Color\Profiles\Recommended
thereby appear first (or at least nearer the top) in drop-down lists. This is helpful if there are alot of profiles in the default (system) area.
"It is a magical time. I am reluctant to leave. Yet the shooting becomes more difficult, the path back grows black as it is without this last light. I don't do it anymore unless my husband is with me, as I am still afraid of the dark, smile.
This was truly last light, my legs were tired, my husband could no longer read and was anxious to leave, but the magic and I, we lingered........"
Ginger Jones
"It is a magical time. I am reluctant to leave. Yet the shooting becomes more difficult, the path back grows black as it is without this last light. I don't do it anymore unless my husband is with me, as I am still afraid of the dark, smile.
This was truly last light, my legs were tired, my husband could no longer read and was anxious to leave, but the magic and I, we lingered........"
Ginger Jones
For personal reasons (maybe the constant headache or maybe that I don't envision needing CMYK output - not sure), I'm having trouble getting too far into the detail of this chapter.
I understand that for neutral the C value must be a few point higher than the M & Y values.
I understand that you can save some overall % total by reducing CM & Y somewhat and increasing K about the same (possibly slightly less of an increase).
I understand that by doing this a bit less ink is thrown at the paper.
Now, to simplify my question.
If I reduce CM & Y by let's say 15% and increase K by about 15%, what actual effect will that have on the colors of the image?
Again, thanks for the great writeup.
(Unrelated- For those interested, I posted, at the end of the Chapter 4 thread, some tricks I learned that helped me complete the quiz on Page 84)
If you do a general, global move, you will destroy your image. Not good. The downside with CMYK is that you have to concern yourself with questions like this, regarding your shadows. The upside is, it's much easier to target blacks since they actually exist as a separate entity, rather than being rolled up in the color channels. So you'll need to restrict your move to the shadows.
Dan suggests using Selective Color, set to Black. Pulling C, M, and Y down by as much as 15% would constitute a fairly drastic shift, but, in theory, replacing it with equal black should accomplish the task.
But not really. those C, M and Y values are pulled from the featureless smudge that constitutes most shadow areas in the color plates, whereas the added blacks contain all the shadow detail. So indiscriminently pouring black on top of itself will probably ruin the shadows. That's why you use a curve in the black channel instead. Unlike other color tools, curves can be precise in the range that they target. In your black plate, you are, of necessity, dealing with a narrow range of detail. A curve allows you to pull the range proportionately, darkening the darkest parts, while retaining some distinction in the lighter areas, retaining detail.
Before Selective Color came along, the trick was to use the black plate as a selection, or a layer mask for a Curve adjustment layer, a trick that I still apply in other spaces. Also, as Rutt pointed out in this same thread, CMYK can be the place to go for any kind of serious shadow work, even if the image will end up in a different space.
—Korzybski
Ok, first ever post to the Digital Grin forum. "Oh Lord please don't let me make a fool of myself".
On to my question. In the situation where I inhabit an entirely RGB based workflow, but I want to make use of the CMYK space for all the usual good reasons of channel mixing etc, why would I create a CMYK profile that reflects the limitations of ink and paper. Could I set the total ink limit to 400% for example? Dot gain to 0%? Does it make any difference with such a workflow?
Welcome to Dgrin and congrats on your first post!
Well, if I understand you correctly... If you're are NOT going to actually use CMYK as your final colorspace and simply want to do some color corrections there with the intention to go back to RGB (or continue to LAB), there is nothing that should stop you from doing all those things you've mentioned, and then some. It's simply a different set of formulas and rules. If it helps you get the results you want faster - sure, why not!
HTH
One is rgbk, the other is wgcmyk. They have an extended cmyk gamut. They allow you to convert from rgb to cmyk and back about as lossless as possible.
Because they don't reflect the limitations of ink and paper they are not meant to be used for output to press.
They have subtle differences. One works better on some images and vice versa.
Regards,
Michael
Graphics23 - Design, Illustration, Restoration & Retouching
What's a Pirate's favorite color mode? Arrrr, G, B!
It's true that you're not really worrying about ink, but if you were to pop your image into CMYK using, say, a max black setting, you would find it impossible to make the kind of shadow moves that are possible using Dan's separation specs. CMYK is simply a better space for shadow work, and the benefits translate back to RGB once you're done. You just need to be real clear about your needs. Not all images require a CMYK move, and for the ones that do, not all separations are equal.
If the issues are color oriented, rather than shadow detail, CMYK can be a mixed bag of results. If your image is heavy with pastels and bright oranges, greens and blues, an ordinary move into CMYK will ruin it. The profiles Micheal mentions could be useful in those cases. (But, then, if you have a pastel-laden image, you might not want a CMYK move at all.) But I find skin tones to be much easier to fine tune in CMYK due to the lack of shadows in the crucial areas of the skin range. In RGB, the curves can rapidly get out of control pretty easily, particularly in the shadow. And the reduced color gamut can work to your advantage. Sometimes I find skin tones that have a day-glo, neon sheen to them, tones that get safely muted and desaturated in CMYK (although that's far from a precise approach.) But sometimes it works. Also, the dot-gain compensation that CMYK conversions perform can offer some work arounds. If your skin tones are too hot, you can get interesting results by making a copy of your Red plate, then converting to CMYK and substituting the original Red for the new Cyan. If you do this in a duplicate layer, peel back the shadows with Blend-if sliders and adjust opacity to taste, you get an boost in real cyan tones rather than the purple hues that result from simply blending magenta into the cyan plate.
So, when should you go into CMYK? Like Dan says, "It depends."
—Korzybski