Colour management with inkjet printers

On 7/18/06 5:19 PM, Mike wrote:
> Hello,
>
> I'm working my way through Dan Margulis's Professional Photoshop book, which
> is heavily geared towards colour correction using curves. I have acheived
> some excellent results using his techniques, but I am a little confused
> about one area in particular and was hoping somebody here who's used the
> book could help me.
>
> I am able to acheive very pleasing colours working in CMYK and setting
> correct black and white points, correct skin tones, correct neutral colours
> etc, as per Dan's advice. However, my confusion arises when I want to print
> a corrected image on my inkjet printer. As I understand it, an inkjet
> printer needs an RGB image which it then converts to its own CMYK profile
> for print. However, when I convert my image back to RGB for printing, there
> is sometimes a subtle change in some of the colours on screen (nothing
> dramatic, but enough for me to notice that some colours are not the same as
> they were in CMYK).
>
> Is this a limitation of using an inkjet (ie. the fact that inkjets need RGB
> images)? Or have I failed to understand something? Also, would I be better
> off saving important images in CMYK and taking them to a decent lab for
> printing instead?

The main question I have is: Why are you working in CYMK? Have you tried
the same techniques with curves on RGB images?

--
John McWilliams
 >> Stay informed about: Colour management with inkjet printers 

On 2006-07-18 20:19:09 -0400, "Mike" <noot1967.RemoveThis@yahoo.co.uk> said:

> Hello,
>
> I'm working my way through Dan Margulis's Professional Photoshop book,
> which is heavily geared towards colour correction using curves. I have
> acheived some excellent results using his techniques, but I am a little
> confused about one area in particular and was hoping somebody here
> who's used the book could help me.
>
> I am able to acheive very pleasing colours working in CMYK and setting
> correct black and white points, correct skin tones, correct neutral
> colours etc, as per Dan's advice. However, my confusion arises when I
> want to print a corrected image on my inkjet printer. As I understand
> it, an inkjet printer needs an RGB image which it then converts to its
> own CMYK profile for print. However, when I convert my image back to
> RGB for printing, there is sometimes a subtle change in some of the
> colours on screen (nothing dramatic, but enough for me to notice that
> some colours are not the same as they were in CMYK).
>
> Is this a limitation of using an inkjet (ie. the fact that inkjets need
> RGB images)? Or have I failed to understand something? Also, would I be
> better off saving important images in CMYK and taking them to a decent
> lab for printing instead?
>
> Thanks for any help.

Basic Photoshop 101... Do your proceesing in the color space of the
final process. If ¥ou are going to take your images ot a professional
printer who uses CMYK then by all means do your work in this
colorspace. On the other hand Inkjet printers are designed to work in
the RGB color spaces, so do your work iin the same. Personaly, my
cameras is set to Adobe RGB, my default workspace in Photoshop and
iPhoto is Adobe RGB and I print in Adobe RGB. Using Apple's
Colorsynce, it all works very well. I do not know of a single under
1000 dollar inkjet designed to deal with CMYK.
My professional printer is very adept at taking RGB color space images
adn doing his magic with CMYK to print.

Jim <jen....not....home..remvdots...@....yahoo
 >> Stay informed about: Colour management with inkjet printers 

Mike wrote:

> As I understand it, an inkjet
> printer needs an RGB image which it then converts to its own CMYK profile
> for print. However, when I convert my image back to RGB for printing, there
> is sometimes a subtle change in some of the colours on screen (nothing
> dramatic, but enough for me to notice that some colours are not the same as
> they were in CMYK).
>
> Is this a limitation of using an inkjet (ie. the fact that inkjets need RGB
> images)? Or have I failed to understand something? Also, would I be better
> off saving important images in CMYK and taking them to a decent lab for
> printing instead?

My understanding of how the average inkjet printer works is that it
expects to receive a file in RGB, then does the conversion to CMYK for
printing. Here's what's happening: You edit in CMYK, convert that to
RGB. The printer converts that RGB back to CMYK. There's bound to be
problems.

If editing in CMYK works for you, and your lab has a printer (inkjet or
whatever) that expects to receive CMYK, go for it. But, don't edit in
CMYK, convert to RGB, & send that file to your inkjet. You're just
defeating your purpose. BTW, you need to learn about color management.
I suggest you Google "color management" & go from there.
 >> Stay informed about: Colour management with inkjet printers 

"bmoag" <aetoo.TakeThisOut@hotmail.com> wrote in message
news:5ofvg.69624$Lm5.64816@newssvr12.news.prodigy.com...
> It is not clear if you have calibrated your monitor. This will allow
> Photoshop to try to match the colors you see with the paper/printer
> profile you choose when you print.
> Monitor calibration and color management will generally get you a decent
> print on the first try but it may not be the best print--that is where
> experience and personal preferences are expressed.
> The ultimate control can be obtained with custom paper/printer profiles
> you generate yourself. However this is expensive even with a newly
> announced device that will run $500-600. The entry price for this gear
> used to be double this.
>

Many thanks for the reply, but it's not a monitor calibration issue. It's a
colour space issue - ie. CMYK versus RGB.

Cheers.
 >> Stay informed about: Colour management with inkjet printers 

"John McWilliams" <jpmcw.TakeThisOut@comcast.net> wrote in message
news:maednRaUqs45GiDZnZ2dnUVZ_vudnZ2d@comcast.com...
> On 7/18/06 5:19 PM, Mike wrote:
>> Hello,
>>
>> I'm working my way through Dan Margulis's Professional Photoshop book,
>> which
>> is heavily geared towards colour correction using curves. I have acheived
>> some excellent results using his techniques, but I am a little confused
>> about one area in particular and was hoping somebody here who's used the
>> book could help me.
>>
>> I am able to acheive very pleasing colours working in CMYK and setting
>> correct black and white points, correct skin tones, correct neutral
>> colours
>> etc, as per Dan's advice. However, my confusion arises when I want to
>> print
>> a corrected image on my inkjet printer. As I understand it, an inkjet
>> printer needs an RGB image which it then converts to its own CMYK profile
>> for print. However, when I convert my image back to RGB for printing,
>> there
>> is sometimes a subtle change in some of the colours on screen (nothing
>> dramatic, but enough for me to notice that some colours are not the same
>> as
>> they were in CMYK).
>>
>> Is this a limitation of using an inkjet (ie. the fact that inkjets need
>> RGB
>> images)? Or have I failed to understand something? Also, would I be
>> better
>> off saving important images in CMYK and taking them to a decent lab for
>> printing instead?
>
> The main question I have is: Why are you working in CYMK? Have you tried
> the same techniques with curves on RGB images?
>
> --
> John McWilliams

I find that CMYK is the best choice for pictures where skin tones need
correcting, also the K channel allows much better control over shadows than
RGB.
 >> Stay informed about: Colour management with inkjet printers 

Oh boy....where to begin. First....Dan has a Yahoo group where you can ask
him and his posse these questions and get very informed answers.
colortheory I think the name of the group is. Second....I find this plug-in
very helpful.... www.curvemeister.com ...and so does Dan as he mentions it
in his Canyon Conundrum book. Third...don't ignore advise you ask for. The
first thing to do when getting serious about control of your color is to get
your monitor as close as you can....Adobe gives you one way. It's better
than nothing. The monitor will never predict accurately what the print will
look like...but that is how life is. You have to give it chance to get as
close as it can.

RGB is a type of color space....there are all kinds of RGB. Which to use is
controversial...but all will handle the values you present with CMYK as CMYK
is very limited....unless you download the wide gamut CMYK from the
Curvemeister. Until you know better use AdobeRGB. I like ProRGB but you have
to know how to use it. It's got a wider gamut than my printer/paper
combination.

Get profiles for your paper/printer combination. If your paper supplier
doesn't have them get another supplier.

Google "Russell Brown Tutorials" and check out the videos on printing from
CS2 to the Epson 2200 printer. I have that combination but the ideas can be
adapted to whatever you use.

--
Thanks,
Gene Palmiter
(visit my photo gallery at http://palmiter.dotphoto.com)
freebridge design group

"Mike" <noot1967.TakeThisOut@yahoo.co.uk> wrote in message
news:e9k1q9$ch0$1@nntp0.reith.bbc.co.uk...
>
> "John McWilliams" <jpmcw.TakeThisOut@comcast.net> wrote in message
> news:maednRaUqs45GiDZnZ2dnUVZ_vudnZ2d@comcast.com...
>> On 7/18/06 5:19 PM, Mike wrote:
>>> Hello,
>>>
>>> I'm working my way through Dan Margulis's Professional Photoshop book,
>>> which
>>> is heavily geared towards colour correction using curves. I have
>>> acheived
>>> some excellent results using his techniques, but I am a little confused
>>> about one area in particular and was hoping somebody here who's used the
>>> book could help me.
>>>
>>> I am able to acheive very pleasing colours working in CMYK and setting
>>> correct black and white points, correct skin tones, correct neutral
>>> colours
>>> etc, as per Dan's advice. However, my confusion arises when I want to
>>> print
>>> a corrected image on my inkjet printer. As I understand it, an inkjet
>>> printer needs an RGB image which it then converts to its own CMYK
>>> profile
>>> for print. However, when I convert my image back to RGB for printing,
>>> there
>>> is sometimes a subtle change in some of the colours on screen (nothing
>>> dramatic, but enough for me to notice that some colours are not the same
>>> as
>>> they were in CMYK).
>>>
>>> Is this a limitation of using an inkjet (ie. the fact that inkjets need
>>> RGB
>>> images)? Or have I failed to understand something? Also, would I be
>>> better
>>> off saving important images in CMYK and taking them to a decent lab for
>>> printing instead?
>>
>> The main question I have is: Why are you working in CYMK? Have you tried
>> the same techniques with curves on RGB images?
>>
>> --
>> John McWilliams
>
> I find that CMYK is the best choice for pictures where skin tones need
> correcting, also the K channel allows much better control over shadows
> than RGB.
>
 >> Stay informed about: Colour management with inkjet printers 

Mike wrote:
> Hello,
>
> I'm working my way through Dan Margulis's Professional Photoshop book, which
> is heavily geared towards colour correction using curves. I have acheived
> some excellent results using his techniques, but I am a little confused
> about one area in particular and was hoping somebody here who's used the
> book could help me.
>
> I am able to acheive very pleasing colours working in CMYK and setting
> correct black and white points, correct skin tones, correct neutral colours
> etc, as per Dan's advice. However, my confusion arises when I want to print
> a corrected image on my inkjet printer. As I understand it, an inkjet
> printer needs an RGB image which it then converts to its own CMYK profile
> for print. However, when I convert my image back to RGB for printing, there
> is sometimes a subtle change in some of the colours on screen (nothing
> dramatic, but enough for me to notice that some colours are not the same as
> they were in CMYK).
>
> Is this a limitation of using an inkjet (ie. the fact that inkjets need RGB
> images)? Or have I failed to understand something? Also, would I be better
> off saving important images in CMYK and taking them to a decent lab for
> printing instead?
>
> Thanks for any help.

Standard ink jet printer drivers and most RIPs going to even pro level
inkjet printers ie Epson pro series need an image in an RGB color
space. As has been said work in Photoshop in the color space you need.
Switching to CMYK greatly reduces your color gamut by switching back to
RGB you are just place an image with a CMYK gamut into an RGB color
space, no magic here once you have lost the color you can't get it
back. So from what I understand, the printer driver will try to conform
to the color space the imge is in and extrapolate the colors from the
color truncated image (CMYK to RGB) so you get some funny looking
colors. CMYK only makes sense when going to offset, and then the CMYK
the printers take is so device specific it is often better to let the
person doing the printing convert the file. When inkjet evolved from 4
color printers to the 6+ color printers now used, CMYK lost its
usefullness.

Tom
 >> Stay informed about: Colour management with inkjet printers 

"One4All" <dwerner.DeleteThis@bresnan.net> wrote in message
news:1153280022.909048.319430@75g2000cwc.googlegroups.com...
>

>
> If editing in CMYK works for you, and your lab has a printer (inkjet or
> whatever) that expects to receive CMYK, go for it. But, don't edit in
> CMYK, convert to RGB, & send that file to your inkjet. You're just
> defeating your purpose. BTW, you need to learn about color management.
> I suggest you Google "color management" & go from there.
>

Thanks for that. However, I have to say that overall I find that editing
some pictures in CMYK and converting to back to RGB does work better than
doing everything in RGB. I'm thinking in particular of skin tones and
pictures where more precise control of shadows are important issues. If I
edit these in CMYK I find I can achieve better results, even after
converting back to RGB, than by doing it all in RGB.

The problem of colour shifts when converting back to RGB happens in a
relatively small number of cases, and isn't such a problem that I would want
to abandon the CMYK space altogether. However, it is something I want to
minimise!

Thanks for all replies.
 >> Stay informed about: Colour management with inkjet printers 

On Wed, 19 Jul 2006 06:37:56 +0100, "Mike" <noot1967.TakeThisOut@yahoo.co.uk>
wrote:


>Thanks for that. However, I have to say that overall I find that editing
>some pictures in CMYK and converting to back to RGB does work better than
>doing everything in RGB. I'm thinking in particular of skin tones and
>pictures where more precise control of shadows are important issues. If I
>edit these in CMYK I find I can achieve better results, even after
>converting back to RGB, than by doing it all in RGB.
>
>The problem of colour shifts when converting back to RGB happens in a
>relatively small number of cases, and isn't such a problem that I would want
>to abandon the CMYK space altogether. However, it is something I want to
>minimise!


In general, CMYK should be considered a "final" color space --
ie, you might convert *to* CMYK if you had a true CMYK RIP,
but it basically never makes sense to convert *from* CMYK
to any other space.

CMYK is 100% device-specific, and there is no unique
representation of any given color in CMYK space. So
basically, any conversion *out* of CMYK space is at
best an educated guess.

CMYK color space only makes sense these days if you're
printing from a dedicated CMYK RIP. Standard printer
drivers, both in the Windoze and Mac world, support
only RGB interfaces for printer drivers.

This is an OS limitation. We all know that standard
desktop printers *do* in fact print using CMYK, with
possible additions of other inks/primaries (eg..,
"light" versions of C, M, K, and even red, green
or blue.


rafe b
www.terrapinphoto.com
 >> Stay informed about: Colour management with inkjet printers 

>
> Thanks for that. However, I have to say that overall I find that editing
> some pictures in CMYK and converting to back to RGB does work better than
> doing everything in RGB. I'm thinking in particular of skin tones and
> pictures where more precise control of shadows are important issues. If I
> edit these in CMYK I find I can achieve better results, even after
> converting back to RGB, than by doing it all in RGB.
>
> The problem of colour shifts when converting back to RGB happens in a
> relatively small number of cases, and isn't such a problem that I would
> want
> to abandon the CMYK space altogether. However, it is something I want to
> minimise!
>

If everything is fine....why bring it up? I prepare work for offset so I
know CMYK pretty well and you are right....some things are easier with it.
But, it has a narrow gamut so going from CMYK to any form of RGB is a bad
move. Get a wide gamut CMYK or the Curveister plug-in if you must use CMYK
and convert to RGB. This gets around the problem. Now you just have to work
on the problem of ignoring good advise.
 >> Stay informed about: Colour management with inkjet printers 

This message is not archived
 >> Stay informed about: Colour management with inkjet printers 

Raphael Bustin wrote:
> ...
> CMYK is 100% device-specific, and there is no unique
> representation of any given color in CMYK space. So
> basically, any conversion *out* of CMYK space is at
> best an educated guess.
> ...

The fact that there is no unique representation of any given color in
CMYK means that any conversion *out* of CMYK space is strictly defined,
while conversions *to* CMYK space have to employ "educated guesses".

--
Best regards,
Andrey Tarasevich
 >> Stay informed about: Colour management with inkjet printers 

Thanks for all replies to this thread - they've been very useful.
 >> Stay informed about: Colour management with inkjet printers