Choosing profiles for forced RGB to CMYK color conversion

When a mixed RGB/CMYK PDF is opened in Illustrator CS6, Illustrator forces a conversion to one color space or the other. See this screenshot: http://imgur.com/sK8iEdn
I assume this is a limitation of Illustrator and there's no way to keep both color spaces. Under that assumption, Is it possible to choose the profiles used for the conversion from RGB to CMYK? Can Illustrator be made to use the RGB and CMYK profiles defined in its Color Settings to make this conversion?

I did some experiments with Illustrator CS6 and the MacBeth RGB test chart and verified my results with Photoshop CS6. I discovered Illustrator is (mostly) doing what it should be doing, within a 1% error (probably rounding) on the output CMYK values. Here's a summary, in case anyone else needs this info:
Assuming the source file's elements are all untagged, when a mixed RGB/CMYK PDF is opened in Illustrator and CMYK mode is
chosen, Illustrator will use the profiles and rendering intent defined in
Color Settings to make the color conversions from RGB to CMYK. Thus, we
have control over the profiles used for this conversion.
If the RGB elements in the PDF file have embedded ICC profiles,
Illustrator will use the embedded ICC profile instead of the RGB profile
defined in Color Settings. This ONLY happens, however, if the PDF file
also includes the correct CMYK output intent profile.
If the PDF doesn't contain a CMYK output intent, Illustrator will fall
back on the Color Settings RGB profile for RGB->CMYK conversion. I believe it
would be more correct for Illustrator to use the embedded RGB profile and
the CMYK profile defined in Color Settings, but that's not how it seems to work.
If the PDF contains the incorrect CMYK output intent, Illustrator will
ignore the Color Settings and respect the embedded RGB and CMYK profiles
for the conversion, as might be expected.

Similar Messages

ICC profile to convert RGB to CMYK,   jpeg is ok, png format have a problem

When I use ICC profile to convert RGB to CMYK, jpeg format is ok, but png format have a problem.the color is lossy.
It means, the png file color is shallow than jpeg file after convert.Could anybody help me?
thanks
source code
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Iterator;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.stream.ImageOutputStream;
import org.w3c.dom.Node;
import com.sun.image.codec.jpeg.ImageFormatException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
public class TestImage {
     public static void main(String args[]) throws ImageFormatException, IOException{
          BufferedImage readImage = null;
          try {
              readImage = ImageIO.read(new File("C:\\TEST.jpg"));
          } catch (Exception e) {
              e.printStackTrace();
              readImage = null;
          readImage = CMYKProfile.getInstance().doChColor(readImage);
          writeImage(readImage, "C:\\TEST_after_.jpg", 1.0f);
    protected static String getSuffix(String filename) {
        int i = filename.lastIndexOf('.');
        if(i>0 && i<filename.length()-1) {
            return filename.substring(i+1).toLowerCase();
        return "";
    protected static void writeImage(BufferedImage image, String filename, float quality) {
        Iterator writers = ImageIO.getImageWritersBySuffix(getSuffix(filename));
        System.out.println("filename�F"+filename);
        if (writers.hasNext()) {
            ImageWriter writer = (ImageWriter)writers.next();
            try {
                ImageOutputStream stream
                    = ImageIO.createImageOutputStream(new File(filename));
                writer.setOutput(stream);
                ImageWriteParam param = writer.getDefaultWriteParam();
                if (param.canWriteCompressed()) {
                    param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);//NO COMPRESS
                    param.setCompressionQuality(quality);
                } else {
                    System.out.println("Compression is not supported.");
                IIOMetadata metadata = null;
                if(getSuffix(filename).equals("png") || getSuffix(filename).equals("PNG")){
                     ImageTypeSpecifier imageTypeSpecifier = new ImageTypeSpecifier(image);
                     metadata = writer.getDefaultImageMetadata(imageTypeSpecifier, param);
                        String sFormat = "javax_imageio_png_1.0";
                        Node node = metadata.getAsTree(sFormat);
                        IIOMetadataNode gammaNode = new IIOMetadataNode("gAMA");
                        String sGamma = "55556";
                        gammaNode.setAttribute("value", sGamma);
                        node.appendChild(gammaNode);
                        metadata.setFromTree(sFormat, node);
                writer.write(null, new IIOImage(image, null, metadata), param);
                writer.dispose();
                return;
            } catch (IOException ex) {
                ex.printStackTrace();
}

Hi,
I am having similar problems. I have read somewhere that png format can not handle CMYK colorspace anyway, which I find odd (and plainly stupid IM(NS)HO) which would mean that converting to RGB and therefore using profiles is mandatory.
May be you should check if the internal format of the png files claims it is RGB or CMYK (using ImageMagick's "identify" command for example).
HTH
JG

How do I find out if a photo in iPhoto is RGB or CMYK color? How do I change from RGB to CMYK?

How do I find out if a photo in iPhoto is RGB or CMYK color? How do I change from RGB to CMYK?

Open the file with Preview, type Command + i to bring up the Info pane and it's color mode and profile will be listed as shown here:
To change the color mode to CMYK you'll need a 3rd party image editor like Photoshotp or GraphicConverter to do it. Why do you need CMYK?
OT

Designing art for both RGB and CMYK

I need to make some artwork that might be viewed in both RGB and printed with CMYK. I know I can switch the color mode after making the artwork, however, I'm concerned with color shifting when changing from RGB to CMYK or the other way around. How do you design something that you can both print and display on screen without compromising the colors?
Thanks.

Generally, is there much if any color shift when going from CMYK to RGB?
Even if a given color is within the gamuts of both CMYK and RGB color spaces, that does not necessarily mean that color shifts will not occur.
You can't think of the RGB and CMYK versions of "a color" as "equivalents." There is not just one set of CMYK values for a given set of RGB values. A simple way to think about it is this: Take the product of three numbers. Now divide that number into four factors. Obviously, there is more than just one set of four values possible.
So switching back and forth between RGB and CMYK color spaces in willy-nilly fashon is not good practice. The software has to make a translation decision out of many possibilities. It does it according to your so-called "color management" settings. Even then, the software does not keep a breadcrumb trail of all of your switches back and forth. So colors can still drift.
Design for print first. Then repurpose for web. Color is not the only reason for this.
JET

Converting RGB to CMYK color

Hi All,
I have few BASIC Questions on converting RGB to CMYK in Photoshop and Illustrator. Hope could get some professional insights here.
1, Are all the DTG printers set only in CMYK color mode ?
2, If there is no difference after viewing RGB image with 'Gamaut Warning' (Photoshop), Does that mean I'll have the exact print result as monitor view ?
and Basically no need for CMYK conversion ?
3, Please list some the most effective way to convert RGB to CMYK, and keep the final CMYK color result as close as the RGB.
4, when I simply convert one RGB image to CMYK color, why Ps/AI don't allow me to save as PNG file ?
( I save the file as PDF, but I cannot edit this PDF using apple preview app )
5, compare Photoshop to Illustrator, which one result better final CMYK color image ?

Thanks for the detailed reply. Sure clear some of the doubts.
I just start to draw/design in Photoshop and illustrator, I save my files most as PNG, for a transparent background.
After I went to officework do the poster printing, I found the color of my print image are not as vivid as Mac preview.
To be precise, the poster I printed looks like has a very thin grey layer, it is not much noticeable, but it indeed lost some vivid color. As I want to print out my works and keep color as close exact as Mac preview, here is the issue of coverting RGB CMYK.
Please feel free to add for below:
1, Should I set color space in CMYK before drawing in PS/AI
2, in PS, I convert profile from PNG file to CMYK save as psd file, that psd file preview exactly same as PNG.
But when saved as PDF, the file preview a bit grey. Can someone explain this?
3, Now im thinking, since CMYK is all about printers, it really should be the profession in printing shop who shall check my image, and edit/convert to the right color space to fit their printers.

How to select matching RGB and CMYK colors

Starting from scratch for a client, how do I select matching RGB and CMYK pairs?
Say we find a nice red colour in RGB for screen use, how do I then find the correct CMYK for print? And what assumptions do I have to make when doing this, if any?
Would it be the same for the other way around (choose CMYK first for print and then find the RGB equivalent)
Is it more sensible to start with a Pantone colour and then find the RGB and CMYK equivalents for that?
Many thanks
RobbieG
(I'm working with Ai, Ps and Id CS6)

Yes. Better to start with Pantone reference books where you are viewing the color in a reflective environment. As already mentioned, color on the monitor can be deceptive. And, I think the others are basiclt saying that you should have everything calibrated and use color management policies in your apps. There is a way to find CMYK equivalents using Photoshop's color palette. Let's say you have an RGB Red as the foreground color in Photoshop. If you double click on the swatch you will get Photoshop's color palette which lists the RGB percentages, CMYK percentages, LAB percentages, and HEX web color for that Red. You can go further and select "Custom" and the Pasntone Spot color palette opens and gives you the closest Spot color value for that Red. This however, depends on your color settings. That's why I recommend you start with the Pantone swatch book and get the perecentages of CMYK from their formula guide which is set to industry standard color.

Automatically convert from RGB to CMYK color mode

I have over 900 barcodes provided in EPS format. When I open them in illustrator, they are coming in as an RGB color space file. I need them gray scale solid black in CMYK color mode. I can batch using actions to convert the artwork using "Edit Colors > Convert to Grayscale". However, the document color mode remains RGB. It appears, even after using "Convert to Grayscale", that the RGB color mode goofs up the placed .ai file in InDesign, treating it as RGB and seeing it as a mix of CMYK rather than the 100% black only it needs to be for proper sharp printing.
The actions pallet doesn't record converting the document color mode. Is there a way to automate that file conversion so they are all saved as CMYK rather than RGB, or am I stuck opening each of the 900+ files manually?

While recording the action, from the popup menu in the Actions Panel choose Insert Menu Item, then from the main menu choose File > Document Color Mode > CMYK color.

The *.icc file is associated with PS process after assigning profile for a picture of CMYK mode ?

Hi everyone, I have a curious problem for your help
My OS is Windows 7. Start PS and open an image, choose "Edit" -> "Assign Profile...", in the pop-up dialog there is a drop-down list showing many system profiles, and I find all of these *.icc files are stored in folder "C:\Windows\System32\spool\drivers\color". Just choose any profile to assign, then go to folder "C:\Windows\System32\spool\drivers\color" and find the related icc file, for example, JapanColor2001Coated.icc is for profile "Japan Color 2001 Coated". Now you can still rename the icc file, that is, the icc file is not taken by photoshop process. Our company has a software to generate icc files, however, when assign these profiles, the icc file is associated with PS process, which means I can't rename or delete the related icc file, even after assigning another profile, unless close the image documents, that is unwanted. So I'd like to know the reason, in fact I'm not very clear about the ICC file structure. I want to make the local disk file not associated with the process so I can do other operations.
Any suggestion will be appreciated.

I made a quick try and I can change the name of various custom profiles I've created using Photoshop but it appears that the name of the profile can't be changed if Photoshop was started with the profile in question selected as a soft proofing profile in View > Proof Setup. You have to quit Photoshop, just changing the soft proofing profile to another is not enough.

Which Color profile for softprofing to print to Apple's book services?

I'm looking for a simple, specific and official answer as to which specific ColorSync profile should I choose for 'Onscreen Proofing' in Aperture? My intended output is Apples Print Services (Hardcover book).
I've crawled the web looking for this simple answer with no luck.
It seems to me that this profile (ie an accurate characterization of Apple's Printing Services) should be at the top of the list (in View/Proofing Profile/). Instead all I could find are discussion forums which hint or guess as to which profile to use.
Alternatively. It should be documented in the manual or the "How to create great looking books?" articles something like: "If you are going to order a book from Apple, then choose the sRGB profile for onscreen proofing. Apple's services are calibrated to this profile and guarantee consistent results". <-- Something like this appears nowhere!
So again. I'm printing my books ($$$) on Apple. Which Proofing profile should I choose?

I'm looking for a simple, specific and official answer as to which specific ColorSync profile should I choose for 'Onscreen Proofing' in Aperture? ... Alternatively. It should be documented in the manual or the "How to create great looking books?" articles something like: "If you are going to order a book from Apple, then choose the sRGB profile for onscreen proofing. Apple's services are calibrated to this profile and guarantee consistent results".
Not sRGB, argghhh -:)
In a colour matching conversion, you have a source colour space (in this case, your ICC type MNTR Monitor profile for your RGB working space) and a destination colour space (in this case an unknown ICC profile, probably of type PRTR Printer).
Your aim in the ICC architecture is to capture into and correct in as large a source colour space as is necessary to contain the colours you can render on the largest colour spaces of displays, printers and presses. This excludes sRGB as source by definition.
The sRGB colour space is the colour space of an HDTV cathode ray tube. This colour space cannot hold colours a lot of output devices can render, including the pure cyan of an ISO 12647 offset printing condition on art paper, and for inkjet sRGB is even worse as source.
Open the Apple ColorSync Utility, select sRGB in the RGB profiles list, click the Disclosure (triangle) icon in the CIELa*b plot, and select Hold for Comparison. Then pick an inkjet profile in the RGB profiles list or a large gamut offset profile in the CMYK profiles list, and turn the 3D graphic to see what can be matched directly and what can be matched only by reshaping the colours.
PDF printing masters can either have only the source ICC profile(s) embedded or both the source and destination ICC profiles. In the former case, the colour matching is done at runtime and you have to wait to see what prints.
In the latter case, you embed the destination ICC profile as OutputIntent and submit PDF/X-3. Since you are allowed to embed either type PRTR Printer or type MNTR Monitor profiles as OutputIntent, and since both are bidirectional for printing as well as for proofing, you have a contract proofing condition.
But in order to work with PDF/X-3 you need to know enough about rendering intents and gamut mapping behaviours that you don't set the wrong rendering intent per object in the page. So a runtime rendering workflow ensures that you get to draw to the maximum gamut available in the printing service, without giving you advanced controls.
/hh

Color converting RGB to CMYK mode???

Is it possible to convert RGB to CMYK color mode in Elements 10?

No, not really. If you google around, Richard Lynch had a sort of workaround for this for very early versions of PSE that could possibly be adapted for current use, but a proper CMYK conversion is much more complex, even with the proper tools, than going from sRGB to Adobe RGB, for example.
If you have a mac you can do a mode conversion in Preview, but you may not like what you get from the print shop using that method.

What color profile for digital printing?

Under color settings in InDesign i only find profiles for offset press but what color profile should i use if i want my document printed on a digital printer?

indewarry wrote:
i just find it strange that there is no 'standard' profile for printing for digital press. All profiles are for conventional press.
Like conventional presses, digital equipment uses a range of inks and papers, so there is no single profile that would always be correct, and the press operator can often calibrate the equipment to one of several differnt standards. I use a printer that offers both offset and digital (using an HP Indigo) printing, and all of their equipment is calibrated to GRAcol.
The fact that the printer couldn't tell you the correct profile is a big red flag shouting that they don't know anything about color management. Don't expect good color fidelity, and insist on a contract proof.

The basics on how to handle profiles correctly when working with LAB colors?

Hello,
I need to incorporate several blocks of color into an InDesign document. I have the colors in a list as LAB values. The document will be printed, and I have the profile for the printer/paper combo we plan to use.
Would one of you be willing to walk me through the Working Space, Color Management Policies, and Assign/Convert Profile setings that I should use to get the best result?
And, specifically - assuming I am using the Color Panel - not swatches - to color in the blocks: What settings should I use inorder to allow me to rely on the provided "out-of-gamut" warning to alert me if I am attempting to use a color that won't print correctly? I don't care if it is out-of-gamut for the purposes of my display - it is whether it is out-ouf-gamut for the purposes of printing that I want to know about.

Do the LAB colors look the same on the monitor regardless of which RGB
you are using? For example, if I switched from sRGB to Adobe RGB, would
the colors which had been specified in LAB still look the same?
Yes. But keep in mind using Lab doesn't let you get around having a well calibrated and profiled monitor. Lab is device independant so it doesn't have a profile, but in order to display it needs to be converted into your monitor's RGB space via your monitor profile, so the accuracy of your monitor profile is important if you are relying on the soft proof.
Is that what is called "Convert to Profile" in InDesign?
When you export to PDF you have the option to force all colors into one destination space (or not). In the Output tab of the Export dialog you can set your Destination to your printer's CMYK profile and the choose Convert to Destination as Color Conversion. That setting will convert your Lab colors to CMYK during the export. Convert to Profile... in the Edit menu let's you convert document RGB or CMYK colors from one RGB or CMYK space to another. It would have no effect on Lab colors.
Is the out-of-gamut warning only for CMYK?
Yes, it's using your document's CMYK space as the gamut
So if I specify a color using LAB which is out-of-gamut for the RGB
space I am using but in-gamut for my CMYK profile, I will NOT see a
warning?
Right. That would be unusual, but the Lab value for 100% cyan in your printer's CMYK space is likely out of gamut to any RGB space. But your destination is CMYK so that's the gamut you care about.

Need Info on RGB to CMYK

Hi,
I am new to Illustrator (CS5) and not fully comfortable with RGB vs CMYK. For instance, I created a logo for use on the web using Document Color Mode: RGB where my background color in RGB is 0, 0, 130. When I create a Print document using Document Color Mode: CMYK and copy the logo into the print document, it converts that background color to CMYK (C:100, M:98, Y:16 K:18) where the RGB is now (44, 45, 111).
Is there a way to get a closer match to the original RGB color 0, 0, 130? When the specifications for the print advertisement says images must be in CMYK, I hope I am accomplishing this by using the Print Document Color Mode of CMYK vs RGB? I feel somewhat ignorant on utilizing the RGB vs CMYK color modes and if anyone can give me a tip on what techniques they use to get a closer match of colors for RGB to CMYK or vice versa, I would love to hear it.
Thank you,
Keith

Keith,
First, be aware that you have posted to the Photoshop forum, not the Illustrator forum. The general concepts of color and color management are the same across the spectrum of digital imaging. However, its implementation is slightly different from application to application, so you may also want to post your question to the Illlustrator forum.
[EDIT: Brain fart on my part... This is the color management forum, NOT the Photoshop forum, so you are in the right place! (I spend most of my time in the Photoshop forum; I lost track of where I was...)]
That said, you're running up against a general concept: color gamut.
The color you've spec'd in your RGB file (0/0/130 - and we'll assume for now that it's in the sRGB color space) is outside the gamut of every CMYK color space. That means that the RGB color you see can not be reproduced using a mix of the four CMYK process colors (cyan, magenta, yellow, black). When converting to CMYK, the software picks the closest color that is within the gamut of the CMYK space, hence the color shift.
When you're designing for CMYK, it's best to work in soft-proof mode which allows you to see a pretty close approximation of what your colors will look like in the final color output space - in your case, CMYK.
In Photoshop, to turn on soft-proof, go to View > Proof Setup> Custom... and choose the CMYK output space that matches the press conditions you are designing for.
There are books written about this, but hopefully this short answer points you in the right direction.
Message was edited by: Rick McCleary

Conversion formulas from RGB to CMYK

Hi,
I've been writing a Colour swatch tool (in excel! hell yeah!) which allows me to pick a bunch of colours, generate complimentary colours from them, blend between 2 colours in a set number of steps and a whole bunch of other cool stuff, and then output this as a photoshop or illustrator swatch file.
As part of this tool I want to be able to covert the rgb values to cmyk. There is very little information on this on the web and what there is is fairly inaccurate.
For example,
RGB:50,128,128
Converts to CMYK 61,0,0,50 (%) using the formula found at easyrgb.com (this formula is the most prevalent one on the web/web forums)
Photoshop converts these RGB values as CMYK: 80,33,48,8 (%)
While these two colour values are *similar* the ones generated by the easyrgb formulas are nowhere near the photoshop values.
See? stupid useless formulas. (I am aware of the differences and overlap of the two gamuts)
Whilst I know that the conversion done in photoshop is done using ICC templates, and that often these conversions are device dependant, there must be a more realiable way of converting from one colour space to another using good old reliable cold hard maths.
Does anyone know what that might be? you guys at Adobe: I AM LOOKING AT YOU.
Hope you guys can help,
~silvery~
For reference I have included and commented the easyrgb formulas:
First: RGB -> CMY
C = 1 - ( R / 255 )
M = 1 - ( G / 255 )
Y = 1 - ( B / 255 )
Second: CMY -> CMYK
var_K = 1
Initally sets var_K as 1, although this is dependant on variables below
if ( C < var_K )   var_K = C
if ( M < var_K )   var_K = M
if ( Y < var_K )   var_K = Y
This bit finds the smallest value from the CMY range and sets this value as var_K
if ( var_K == 1 ) { //Black
    C = 0
    M = 0
    Y = 0
If var_K (the value that K is calculated from) is 1, then all the CMY values are reset to 0
else {
    C = ( C - var_K ) / ( 1 - var_K )
    M = ( M - var_K ) / ( 1 - var_K )
    Y = ( Y - var_K ) / ( 1 - var_K )
If the value of var_K is anything other than 1 then use the smallest value from the CMY range
K = var_K
The value of K as filtered out from the conditions above

Oliver,
I'm not sure what you mean by the term 'meta' color profiles, but I'll take a stab at what I "think" you are asking. There are some fairly widely accepted "standards" out there for both RGB and CMYK.
In the RGB world, for example, sRGB, Adobe RGB (and to some extent, ProPhoto RGB) have a fairly wide following. These are all ICC profiles, which nail down the boundaries of the color gamut and the definitions of any tri-stimulus combination of red, green and blue. Basically, they are matrix profiles that establish the positions of the Red, Green and Blue primaries, and these positions define the outer limits, or color gamut, of the color space. sRGB is a relatively small color space, so some viewable and printable colors get clipped (sRGB is the general internet, email standard and is widely assumed for many non-color managed appplications, printers, etc). sRGB can handle a fairly wide range of colors, but does clip some colors in brightly colored originals. It has the advantage of being the most widely adopted standard, plus the steps between colors are very close together. I use sRGB for average images, most people pictures, etc. Adobe RGB spreads the primaries further apart, so it describes a wider color gamut. Because the primaries are further apart, the steps are slightly larger from one color to the next, but marginally so. I use Adobe RGB for most of my brightly colored images that will get clipped in sRGB. Adobe RGB is also generally a good choice for images that will ultimately go to a printing press or inkjet. ProPhoto RGB pushes the primaries WAY apart, so it describes a HUGE color gamut...in fact, many of the colors that can be defined in ProPhoto fall outside human vision, and certainly monitors and printers.Due to the wide spacing of steps in ProPhoto RGB, images should be worked in in 16 bit, otherwide you may see some banding and posterization if large edits are made.
In the CMYK world, certain "standards" have been established, mainly for commercial offset printers (both web and sheetfed presses). By creating a standard, they are trying to establish the ink limit, densities, color gamut, dynamic range, gray balance, etc, of a "generic" sheet of commercial printing paper on the average well-maintained press using standard ISO inks, using good process control, mesurements, etc. By it's nature, this process has to encompass a wide cross section of presses, so it may act as a limitation on what some modern presses are capable of, but that's what standards usually do. If a good printer, with a modern press and great process control decides to sidestep the standard, they can probably extend color gamut, dynamic range, etc, but at the cost of no longer being "standardized". If commercial printers are "truly" trying to meet the standard, they will run tests, take measurements, and adjust their entire workflow so it matches the standard, within acceptable tolerances. Lots of shops "claim" to adhere to SWOP or GRACoL standards, but the majority of them don't. Standards for presses make some sense, because blending CMYK inks together (especially if they use ISO standard inks) on paper usually has a reasonably narrow range that works, though the paper makes a huge difference. (the same cannot be said for inkjets, monitors and many other processes, so they generally do not have standards). So for presses, there are standards for matte and coated papers, web presses, sheetfed presses, newsprint, etc. Each of these standards has its own ICC profile (or a family of profiles) that establishes ink limits, color gamuts, etc.
All ICC profiles have the necessary tags and data to comply with the ICC specification. One of those requirements is a "profile connection space", which is usually L*a*b* or a variant. So, an file on your computer may be tagged as an Adobe RGB file, and if you wish to prepare it for a sheetfed press using glossy stock, you could convert the file to GRACoL2006_Coated1v2.ICC (an industry standard profile for No. 1 coated stock on a sheetfed press). Since both files have the ability to "speak Lab" a translation can be made from one color space to the other. The numbers in the Adobe RGB file will be converted to L*a*b* (the universal translator), and then the L*a*b* numbers will be converted to CMYK, specifically GRACoL2006_Coated1v2.ICC. So, now you have a file in CMYK space with new numbers. It is worth noting that RGB has only three colorants to define colors, but CMYK has four. So, while in RGB there is only one way to define a specific color, in CMYK, there are many possible combinations that can generate many colors. This adds complexity to the equation. The CMY colors are called subtractive primaries, and are opposites of RGB (additive primaries). The "K" (black ink) is added for text, line art, neutrality, extra Dmax, and because the CMY inks are not pure and don't deliver a true black all by themselves. If the inks and paper were perfect, you could theoretically get away with CMY all by themselves, except for registration issues, text, line art, etc. Also, the additional "K" ink can help reduce the total ink limit, save ink, reduce costs, and improve quality.
Sorry for the book. This is not a simple subject, and we have only touched the surface.
Lou

Convert rgb to cmyk in bridge

I am working on a MAC & Photoshop CS2. I
need a how-to action for converting RGB
to CMYK & how to image process it in Bridge.
Many thanks.

If you create an RGB>CMYK action in Photoshop you can easily pick images in Bridge and call up a Batch operation from within Bridge...but it's Photoshop doing the work cause Bridge ain't an image processor (as others have said).

Choosing profiles for forced RGB to CMYK color conversion

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