How to change from RGB to CMYK. I am desperate. I have a deadline to get my PDF image printed. My problem is: I need to change a PDF image which contains text also from RGB to CMYK. The document will be sent to an outside printer. Learn when should you configure your working space to RGB, CMYK or Grayscale color space in Adobe Acrobat. Also, the Color Conversion options to effectively control how your application handles the colors in a document as it moves from one color space to another.
A working space is an intermediate color space used to define and edit color in Adobe applications. Each color model has a working space profile associated with it. You can choose working space profiles in the Settings menu of the Color Management category of the Preferences dialog box.
If an object has an embedded color profile that doesn’t match the working space profile, the application uses a color management policy to determine how to handle the color data. In most cases, the default policy is to preserve the embedded profile.
Select the Color Management categoryof the Preferences dialog box.
Note:
To view a description of any profile, select the profile. The description appears at the bottom of the dialog box.
Determines the RGB color space of the application. In general, it’s best to choose Adobe RGB or sRGB, rather than the profile for a specific device (such as a monitor profile).
sRGB is recommended when you prepare images for the web or mobile devices, because it defines the color space of the standard monitor used to view images on the web. sRGB is also a good choice when you work with images from consumer-level digital cameras, because most of these cameras use sRGB as their default color space.
Adobe RGB is recommended when you prepare documents for print, because Adobe RGB’s gamut includes some printable colors (cyans and blues in particular) that can’t be defined using sRGB. Adobe RGB is also a good choice when working with images from professional-level digital cameras, because most of these cameras use Adobe RGB as their default color space.
Determines the CMYK color space of the application. All CMYKworking spaces are device-dependent, meaning that they are basedon actual ink and paper combinations. The CMYK working spaces Adobesupplies are based on standard commercial print conditions.
Determines the grayscale color space of the application.
Note:
You can use the color space in an embedded output color space for viewing and printing. For more information on output intents, see Color conversion and ink management (Acrobat Pro).
Adobe applications ship with a standard set of working space profiles that have been recommended and tested by Adobe for most color management workflows. By default, only these profiles appear in the working space menus.
Unless specifiedotherwise, the document uses the working space profile associatedwith its color mode for creating and editing colors. However, some existingdocuments may not use the working space profile that you have specified,and some existing documents may not be color-managed. It is commonto encounter the following exceptions to your color-managed workflow:
- You might open a document or import color data (for example,by copying and pasting or dragging and dropping) from a documentthat is not tagged with a profile. This is often the case when youopen a document created in an application that either does not supportcolor management or has color management turned off.
- You might open a document or import color data from a documentthat is tagged with a profile different from the current workingspace. This may be the case when you open a document that was createdusing different color management settings, or scanned and taggedwith a scanner profile.
In either case, the application uses a color management policyto decide how to handle the color data in the document.
Colorconversion options let you control how the application handles thecolors in a document as it moves from one color space to another.Changing these options is recommended only if you are knowledgeableabout color management and very confident about the changes youmake. To display conversion options, select the ColorManagement category of the Preferences dialog box.
Specifies the Color Management Module (CMM) used to map the gamut of one color space to the gamut of another. For most users, the default Adobe (ACE) engine fulfills all conversion needs.
Note:
To view a description of an engine or intent option, select the option. The description appears at the bottom of the dialog box.
Ensuresthat the shadow detail in the image is preserved by simulating thefull dynamic range of the output device. Select this option if youplan to use black point compensation when printing (which is recommendedin most situations).
A rendering intent determines howa color management system handles color conversion from one colorspace to another. Different rendering intents use different rulesto determine how the source colors are adjusted; for example, colorsthat fall inside the destination gamut may remain unchanged, orthey may be adjusted to preserve the original range of visual relationshipswhen translated to a smaller destination gamut. The result of choosinga rendering intent depends on the graphical content of documentsand on the profiles used to specify color spaces. Some profilesproduce identical results for different rendering intents.
Note:
In general, it is best to use the default rendering intent for the selected color setting, which has been tested by Adobe to meet industry standards. For example, if you choose a color setting for North America or Europe, the default rendering intent is Relative Colorimetric.. If you choose a color setting for Japan, the default rendering intent is Perceptual.
You can select a rendering intent when you set color conversionoptions for the color management system, soft-proof colors, andprint artwork:
Aims to preserve the visual relationship between colors soit’s perceived as natural to the human eye, even though the colorvalues themselves may change. This intent is suitable for photographicimages with lots of out-of-gamut colors. This is the standard renderingintent for the Japanese printing industry.
Tries to produce vivid colors in an image at the expenseof color accuracy. This rendering intent is suitable for businessgraphics like graphs or charts, where bright saturated colors aremore important than the exact relationship between colors.
Compares the extreme highlight of the source color spaceto that of the destination color space and shifts all colors accordingly.Out-of-gamut colors are shifted to the closest reproducible colorin the destination color space. Relative Colorimetric preservesmore of the original colors in an image than Perceptual. This isthe standard rendering intent for printing in North America andEurope.
Leaves colors that fall inside the destination gamut unchanged.Out-of-gamut colors are clipped. No scaling of colors to destination whitepoint is performed. This intent aims to maintain color accuracyat the expense of preserving relationships between colors and issuitable for proofing to simulate the output of a particular device.This intent is particularly useful for previewing how paper coloraffects printed colors.
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Is it possible to pre-process (in batch) PDFs that are in CMYK format to separate out into spot colours?
I have a collection of PDFs that are in CMYK but I require them to be in a 2 spot colour format.
The colours are red and black. The black (K) is fine, but the red spot needs to be a merge of the Magenta & Yellow.
Is this possible at all? I'd prefer something that would be able to separate spots based on a given colour rather than merging colours as that becomes very limited.
I've looked in adobe acrobat X pro and that doesn't seem to do what I want. I could probably do it manually in photoshop but it would be a long winded process for the large amount of PDFs I have.
TheStoneFoxTheStoneFox1,63711 gold badge2222 silver badges4343 bronze badges
2 Answers
I'm guessing this problem was long solved, but just for completeness; yes, this can be done. There are a number of commercial tools that do exactly this very easily actually.
1) If I'm not mistaken, the latest version of Adobe Acrobat actually contains a lot more PDF file correction possibilities than previous versions, which means it should be able to do this.
2) There are tools like callas pdfToolbox (warning, I'm affiliated with this company/product) that can pre-process a PDF file pretty much any which way you want.
In general though I think the first question would be why you go through the RGB to CMYK step - the tools than can do this kind of remapping would equally be able to simply go from Black and Red RGB directly to two named spot colors, avoiding the unnecessary CMYK conversion.
By the way, if what you are trying to obtain is a PDF where you can switch one color off easily (such as for example to hide the correct answers), there are probably better ways to do this. Such as putting all red text on one layer for example, while putting all black text on a different layer (or OCG - optional content group as PDF calls them). This would give you to capability to switch colored text on or off at will, even in something like Adobe Reader.
David van DriesscheDavid van Driessche4,87411 gold badge1717 silver badges3333 bronze badges
This is the simple implementation which will print solid black or anything that is not black. Depending on your needs, it may need to get more complex. Without knowing more, I took the brute force approach of using exitserver. exitserver allows the default operation of the RIP to be redefined. To restore the RIP to its normal operation, you need to reboot the rip or write another exit server routine to undefine the server modification.
The routine is installed in the rip by sending the exitserver postscript code. For a PC, this can be done with a DOS copy command to the printers share. There are also sendps programs which can be found on the web to sent the file to the device.
This exitserver routine defines a /setcmykcolor function in the userdict, which will take precedence over the setcmykcolor in the system dict. there will 4 numbers on the stack where the last in will be the black. The back value is duplicated and compared to zero. If the black is not zero, the black block will be performed, otherwise the not black will execute. 0 setgray=black and 1 setgray=white, so as the block exists below, black will print as black and everything else will print as white.
By reversing the value of setgray, the black will not print and everything else 'not black' would print.
It won't matter what program you print from. whichever version of the exitserver is last loaded, will be the way the output will print.
Here is a simple .ps example
The output will display only 'black' or 'not black', but the text overprints, so you will see a ghost image of whichever color is not printing.
This is an exitserver to restore the RIP to use the normal setcmykcolor
As stated at the beginning, this is a simple implementation, such as allowing tints of black and not black There could also be variations of colors where small amounts of black mixed with color could fool the simple routine to where a dark red 0 .87 .75 .1 setcmykcolor would be defined as black, where it probably should be not-black.
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