Widest Gamut CMYK in or available for PS?

D
Posted By
DL
Feb 12, 2004
Views
2058
Replies
15
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Closed
Hi, as I continue reading "Professional Photoshop" by Margulis I’m trying some of his techniques that involve adjusting color in CMYK. However, my primary targets are the Web and a Canon i9100 printer, not a commercial press. So what I’d like to do is be able to convert from an RGB color space to a CMYK space without loosing some of the colors I see going away on the CMYK conversion.

So, what’s the best (widest gamut) CMYK space/profile in Photoshop CS (or elsewhere?) TIA!

-Dick L.
http://home.houston.rr.com/dtlocke/pix.html

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W
Waldo
Feb 12, 2004
Why would you convert to CMYK? Browsers don’t support CMYK JPEGs and your prints will get worse when designed in CMYK as it is a RGB printer (no RGB inks, it has 6 inks, including C, M, Y and K and two others, but when printing, your design is converted to RGB first and in the printer it is converted to the 6 proces colors. You should try to keep color conversions to a minimum, because that’s not good for the final quality, I experienced that when designing in CMYK for my HP 970. RGB images came out much better.).

Waldo

"DL" wrote in message
Hi, as I continue reading "Professional Photoshop" by Margulis I’m trying
some
of his techniques that involve adjusting color in CMYK. However, my
primary
targets are the Web and a Canon i9100 printer, not a commercial press. So
what
I’d like to do is be able to convert from an RGB color space to a CMYK
space
without loosing some of the colors I see going away on the CMYK
conversion.
So, what’s the best (widest gamut) CMYK space/profile in Photoshop CS (or elsewhere?) TIA!

-Dick L.
http://home.houston.rr.com/dtlocke/pix.html
RF
Robert Feinman
Feb 12, 2004
In article ,
says…
Hi, as I continue reading "Professional Photoshop" by Margulis I’m trying some of his techniques that involve adjusting color in CMYK. However, my primary targets are the Web and a Canon i9100 printer, not a commercial press. So what I’d like to do is be able to convert from an RGB color space to a CMYK space without loosing some of the colors I see going away on the CMYK conversion.
So, what’s the best (widest gamut) CMYK space/profile in Photoshop CS (or elsewhere?) TIA!

-Dick L.
http://home.houston.rr.com/dtlocke/pix.html
What you probably want to do is use the soft proofing on screen before printing. You select the profile to proof with from a drop list after you choose "custom". Your printer should have installed some standard ones, but you will get better results if you make your own with custom profiling software such as that from Monaco.
This way you will get a good inpression of how your print will look before you print it.
I have a tip on a workflow designed for inkjet prints in the tips section of my web site.


Robert D Feinman

Landscapes, Cityscapes, Panoramas and Photoshop Tips
http://robertdfeinman.com
EG
Eric Gill
Feb 12, 2004
"Waldo" wrote in
news::

Why would you convert to CMYK?

There are a number of color correction techniques made for CMYK, and many experienced layout artists work better in it, or the advice they give is tailored for it.

Browsers don’t support CMYK JPEGs and
your prints will get worse when designed in CMYK

That’s why he was asking for wide-gamut CMYK. No or minimal conversion losses.

<snip>
D
dtlnew
Feb 12, 2004
I want to convert to CMYK to facilitate certain types of color corrections as described in the book I mention. -Dick L.

"Waldo" …
Why would you convert to CMYK? Browsers don’t support CMYK JPEGs and your prints will get worse when designed in CMYK as it is a RGB printer (no RGB inks, it has 6 inks, including C, M, Y and K and two others, but when printing, your design is converted to RGB first and in the printer it is converted to the 6 proces colors. You should try to keep color conversions to a minimum, because that’s not good for the final quality, I experienced that when designing in CMYK for my HP 970. RGB images came out much better.).

Waldo

"DL" wrote in message
Hi, as I continue reading "Professional Photoshop" by Margulis I’m trying
some
of his techniques that involve adjusting color in CMYK. However, my
primary
targets are the Web and a Canon i9100 printer, not a commercial press. So
what
I’d like to do is be able to convert from an RGB color space to a CMYK
space
without loosing some of the colors I see going away on the CMYK
conversion.
So, what’s the best (widest gamut) CMYK space/profile in Photoshop CS (or elsewhere?) TIA!

-Dick L.
http://home.houston.rr.com/dtlocke/pix.html
D
dglaser
Feb 13, 2004
I came across a couple of sites by, I think, the same person which discusses this issue of conversion between RGB and CMYK pretty well, with visual comparisions and he even includes download files of wide gamut CMYK profiles, or whatever they are called, that you can set PhotoShop to in your preferences. Plus he has designed a Curves tool for editing in wide gamut CMYK without even converting!

http://www.geigy.2y.net/DigPhoto/Tutorials.htm

http://www.curvemeister.com/

I think you’ll find his site really valuable.

Dale
D
DL
Mar 1, 2004
OK, it turns out that the author notes that he’s included two wide gamut CMYK profiles in the CD that came with his book. I wish he would have noted that a bit earlier!

-Dick L.

On Thu, 12 Feb 2004 04:46:28 GMT, DL wrote:

Hi, as I continue reading "Professional Photoshop" by Margulis I’m trying some of his techniques that involve adjusting color in CMYK. However, my primary targets are the Web and a Canon i9100 printer, not a commercial press. So what I’d like to do is be able to convert from an RGB color space to a CMYK space without loosing some of the colors I see going away on the CMYK conversion.
So, what’s the best (widest gamut) CMYK space/profile in Photoshop CS (or elsewhere?) TIA!

-Dick L.
http://home.houston.rr.com/dtlocke/pix.html
CC
Chris Cox
Mar 3, 2004
Since you are targetting a desktop printer – you’d be better off working in RGB and not incurring further losses when you print (because the printer can only accept RGB data).

Chris

In article , DL
wrote:

OK, it turns out that the author notes that he’s included two wide gamut CMYK profiles in the CD that came with his book. I wish he would have noted that a bit earlier!

-Dick L.

On Thu, 12 Feb 2004 04:46:28 GMT, DL wrote:

Hi, as I continue reading "Professional Photoshop" by Margulis I’m trying some
of his techniques that involve adjusting color in CMYK. However, my primary targets are the Web and a Canon i9100 printer, not a commercial press. So what
I’d like to do is be able to convert from an RGB color space to a CMYK space without loosing some of the colors I see going away on the CMYK conversion.
So, what’s the best (widest gamut) CMYK space/profile in Photoshop CS (or elsewhere?) TIA!

-Dick L.
http://home.houston.rr.com/dtlocke/pix.html
D
DL
Mar 3, 2004
Chris,

I agree that my printer can only accept RGB data, and that converting between RBG, CMYK, and back again can result in image degradation. That’s what motivated my original question, which was how can I do this with minimal or no loss?

Every image has 10 channels as Dan Magulis points out in "Professional Photoshop." (That’s RGB, CMYK, and the 3 Lab channels if that’s not obvious.) There are a number of powerful color correction techniques described in that book requiring a trip into CMYK. I want to have the CMYK tricks in my bag, but not suffer the image loss you might see. The Wide Gamut CMYK profiles should one to do that.

-Dick L.

On Wed, 03 Mar 2004 00:09:53 GMT, Chris Cox wrote:

Since you are targetting a desktop printer – you’d be better off working in RGB and not incurring further losses when you print (because the printer can only accept RGB data).

Chris

In article , DL
wrote:

OK, it turns out that the author notes that he’s included two wide gamut CMYK profiles in the CD that came with his book. I wish he would have noted that a bit earlier!

-Dick L.

On Thu, 12 Feb 2004 04:46:28 GMT, DL wrote:

Hi, as I continue reading "Professional Photoshop" by Margulis I’m trying some
of his techniques that involve adjusting color in CMYK. However, my primary targets are the Web and a Canon i9100 printer, not a commercial press. So what
I’d like to do is be able to convert from an RGB color space to a CMYK space without loosing some of the colors I see going away on the CMYK conversion.
So, what’s the best (widest gamut) CMYK space/profile in Photoshop CS (or elsewhere?) TIA!

-Dick L.
http://home.houston.rr.com/dtlocke/pix.html
F
Flycaster
Mar 3, 2004
"DL" wrote in message
Chris,

I agree that my printer can only accept RGB data, and that converting
between
RBG, CMYK, and back again can result in image degradation. That’s what motivated my original question, which was how can I do this with minimal
or no
loss?

Every image has 10 channels as Dan Magulis points out in "Professional Photoshop." (That’s RGB, CMYK, and the 3 Lab channels if that’s not
obvious.)

No, you’re missing the point of what Margulis really meant. What he means is every image can be manipulated using whatever colorspace you want, and in the the case of PS that offers you a total of ten channels. But, and this is point you’re missing, every image *starts out* in one, and only one, color space.

CMYK and LAB are not "hidden" channels in an RGB image. They don’t exist until you actually convert the file. For example, the only way you can get from RGB to CMYK, or back the other way, is by converting. If we assume no gamut clipping, whether or not that conversion will *visually* degrade the image is debatable, but it *will* degrade the image due to rounding errors. Those errors are a fact of conversion, and there is nothing you can do about it. Not even Margulis denies this.

Now, fwiw, I’ve read that the conversion (in PS) from any space to LAB and back causes the least damage since PS apparently uses LAB in the backgound for all images. I’ve never seen anyone like Chris come right out and say that, however, so take it with a grain of salt. In any event, many experts suggest using LAB conversionws, or adjustment layer modifications (eg, fade) to take advantage of the attributes of working in LAB (especially the use of the Luminosity channel) since there is so little "damage." Like I said, though, I’ve got no proof of this.

There are a number of powerful color correction techniques described in
that
book requiring a trip into CMYK. I want to have the CMYK tricks in my bag
, but
not suffer the image loss you might see. The Wide Gamut CMYK profiles
should
one to do that.

There are those who think it (CMYK) can be a valuable tool for RGB images, and Margulis is obviously among them. Then again, there are well known authors and PS experts who think it is totally unnecessary and simply slams the file for no good reason. Thus, I guess it goes without saying that Margulis has his disciples as well as his detractors.

By all means, give it a shot. Try it for yourself, make prints, and be critical.

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D
DL
Mar 5, 2004
If a human being can’t detect the mathematical "errors" introduced by conversions to a color space, I’d suggest the errors are irrelevant. Maybe this is a philosophical thing, but isn’t the whole point of color correcting an image to change the image (the numbers) from whatever they were to something that looks better? The numbers aren’t sacred. And if you hose the image up, you go back to your backup copy 😉

Back to the original topic, which was is there a wide gamut CMYK space I can use for color correction purposes that will have little or no conversion penalty. I’ve experimented with Margulis’ "rgbk" (CMYK) profile enough to convince myself that any penalties in converting are minor on most images. Need to check out some blue sky pix, though.

-Dick L.
On Tue, 2 Mar 2004 19:03:07 -0800, "Flycaster" wrote:

"DL" wrote in message
Chris,
….
Every image has 10 channels as Dan Magulis points out in "Professional Photoshop." (That’s RGB, CMYK, and the 3 Lab channels if that’s not
obvious.)

No, you’re missing the point of what Margulis really meant. What he means is every image can be manipulated using whatever colorspace you want, and in the the case of PS that offers you a total of ten channels. But, and this is point you’re missing, every image *starts out* in one, and only one, color space.

CMYK and LAB are not "hidden" channels in an RGB image. They don’t exist until you actually convert the file. For example, the only way you can get from RGB to CMYK, or back the other way, is by converting. If we assume no gamut clipping, whether or not that conversion will *visually* degrade the image is debatable, but it *will* degrade the image due to rounding errors. Those errors are a fact of conversion, and there is nothing you can do about it. Not even Margulis denies this.

Now, fwiw, I’ve read that the conversion (in PS) from any space to LAB and back causes the least damage since PS apparently uses LAB in the backgound for all images. I’ve never seen anyone like Chris come right out and say that, however, so take it with a grain of salt. In any event, many experts suggest using LAB conversionws, or adjustment layer modifications (eg, fade) to take advantage of the attributes of working in LAB (especially the use of the Luminosity channel) since there is so little "damage." Like I said, though, I’ve got no proof of this.

There are a number of powerful color correction techniques described in
that
book requiring a trip into CMYK. I want to have the CMYK tricks in my bag
, but
not suffer the image loss you might see. The Wide Gamut CMYK profiles
should
one to do that.

There are those who think it (CMYK) can be a valuable tool for RGB images, and Margulis is obviously among them. Then again, there are well known authors and PS experts who think it is totally unnecessary and simply slams the file for no good reason. Thus, I guess it goes without saying that Margulis has his disciples as well as his detractors.

By all means, give it a shot. Try it for yourself, make prints, and be critical.

—–= Posted via Newsfeeds.Com, Uncensored Usenet News =—– http://www.newsfeeds.com – The #1 Newsgroup Service in the World! —–== Over 100,000 Newsgroups – 19 Different Servers! =—–
F
Flycaster
Mar 5, 2004
"DL" wrote in message
If a human being can’t detect the mathematical "errors" introduced by conversions to a color space, I’d suggest the errors are irrelevant.
Maybe this
is a philosophical thing, but isn’t the whole point of color correcting an
image
to change the image (the numbers) from whatever they were to something
that
looks better? The numbers aren’t sacred. And if you hose the image up,
you go
back to your backup copy 😉

I don’t think the arguments against it are philosphical. Like I said, there are those who complain of visible file damage with just a conversion or two. Others say they can’t see a thing. Take your pick, but run your own tests.

Personally, I don’t bother – I’ve yet to see where an image where a conversion would help my RGB work. But that’s me.

Back to the original topic, which was is there a wide gamut CMYK space I
can use
for color correction purposes that will have little or no conversion
penalty.
I’ve experimented with Margulis’ "rgbk" (CMYK) profile enough to convince
myself
that any penalties in converting are minor on most images. Need to check
out
some blue sky pix, though.

There is, and I don’t know why the fella hasn’t chimed in yet. Do a google search on "curvemeister." It should be there somewhere.

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F
Flycaster
Mar 5, 2004
Sorry for the poor grammar. It’s been a long day and I’m beat.

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MR
Mike Russell
Mar 5, 2004
DL wrote:
If a human being can’t detect the mathematical "errors" introduced by conversions to a color space, I’d suggest the errors are irrelevant. Maybe this is a philosophical thing, but isn’t the whole point of color correcting an image to change the image (the numbers) from whatever they were to something that looks better? The numbers aren’t sacred. And if you hose the image up, you go back to your backup copy 😉

Back to the original topic, which was is there a wide gamut CMYK space I can use for color correction purposes that will have little or no conversion penalty. I’ve experimented with Margulis’ "rgbk" (CMYK) profile enough to convince myself that any penalties in converting are minor on most images. Need to check out some blue sky pix, though.

Check out www.curvemeister.com – there is a windows-only plugin there that, among other things, will do wide gamut CMYK with very close to no mathmatical change to your RGB colors. The demo includes several informative tutorials on using curves.

There is also a free download there of my wide gamut CMYK profile, which is one of the profiles distributed on the CD that accompanies the 4th edition of Professional Photoshop. This profile has a very low conversion penalty, but there are some changes to colors. More importantly, being a single profile, it is limited to a single GCR setting.


Mike Russell
www.curvemeister.com
www.geigy.2y.net
S
Sean
Mar 7, 2004
On Fri, 05 Mar 2004 02:57:55 GMT, DL reverently
intoned upon the aether:

If a human being can’t detect the mathematical "errors" introduced by conversions to a color space, I’d suggest the errors are irrelevant. Maybe this is a philosophical thing, but isn’t the whole point of color correcting an image to change the image (the numbers) from whatever they were to something that looks better? The numbers aren’t sacred. And if you hose the image up, you go back to your backup copy 😉

Back to the original topic, which was is there a wide gamut CMYK space I can use for color correction purposes that will have little or no conversion penalty. I’ve experimented with Margulis’ "rgbk" (CMYK) profile enough to convince myself that any penalties in converting are minor on most images. Need to check out some blue sky pix, though.

-Dick L.

Since you have no intentions of going to press with your CMYK files the first thing you should do is set the ink limit for your default CMYK space to 400. This way ink limits do not impose themselves on your colors. Now IIRC you should also be using the absolute colorimetric conversion. Thus if a pixel is a color, then it will remain that color unless it cannot be reproduced in the new color space.

Generally speaking, AdobeRGB 1998 is a pretty large color space and will induce minimal clipping in the CMYK->RGB conversion.

Another factor you can use to minimize color space conversion damage is to work in 16-bit mode. Personally, I always duplicate an image before converting to work in CMYK mode and then convert back and paste the changes as a new layer. Then I can set the blending mode to luminosity if that give better color or keep the new colors.

And in the end the only thing that matters is that the image looks good.

enjoy,

Sean

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

Photo Archive @ http://www.tearnet.com/Sean
S
Sean
Mar 7, 2004
On Thu, 4 Mar 2004 19:25:06 -0800, "Flycaster" reverently intoned upon the aether:

"DL" wrote in message
If a human being can’t detect the mathematical "errors" introduced by conversions to a color space, I’d suggest the errors are irrelevant.
Maybe this
is a philosophical thing, but isn’t the whole point of color correcting an
image
to change the image (the numbers) from whatever they were to something
that
looks better? The numbers aren’t sacred. And if you hose the image up,
you go
back to your backup copy 😉

I don’t think the arguments against it are philosphical. Like I said, there are those who complain of visible file damage with just a conversion or two. Others say they can’t see a thing. Take your pick, but run your own tests.

It depends upon the rendering intent you use. If you use the wrong one for the image you are working with and the color spaces you are using, then yes it will cause your grief. But if you are careful it is not noticeable (and I often inspect images at 500% zoom).

Personally, I don’t bother – I’ve yet to see where an image where a conversion would help my RGB work. But that’s me.

The careful usage of GCR and UCR in the conversion to CMYK can make it easy to isolate key features in an image. You can also sharpen the black channel only in an image with no white highlights and never blow the highlights out to pure white when there should not be any.

enjoy,

Sean

"In the End, we will remember not the words of our enemies, but the silence of our friends."

– Martin Luther King Jr. (1929-1968)

Photo Archive @ http://www.tearnet.com/Sean

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