Setting up a "Convert colors" Fixup

The "Convert colors" Fixup offers very powerful and flexible options for converting colors in many ways, allowing for highly customizable color conversion settings e.g. how different types of page objects are handled during color conversion and what the destination Profile of the color conversion process is. The Fixup consists of three sections. Let's take a look at each one.

1. Destination

Destination

In this list you can specify the destination profile that shall be used as the destination for the color conversion. In any case, this will only have an effect if 'Convert to destination' or 'Convert only alternate color space to destination' is chosen as Conversion in the "Conversion settings" area.

Use Destination Profile from Output Intent if present

An Output Intent has two meanings in color conversion:

1. Definition of the destination profile for color conversion (except DeviceLink)

2. Definition of the Output Intent for the resulting file

If this checkbox is activated and the processed PDF file contains an Out­put Intent, the profile chosen in the Destination list will be ignored and instead the one embedded in the Output Intent will be used.

Embedding

Do not embed

Converted objects are not tagged at all.

Embed as source profile

All converted objects will be tagged with the destination profile. This will hardly ever be useful for conversions to CMYK but is almost always very useful for conversions to RGB.

Embed as Output Intent for PDF/X

An Output Intent will be created for the PDF with the destination profile embedded as Output Intent profile.

  • Note: This is highly recommended for any conversions to CMYK, as recent versions of Adobe Acrobat use that information by default for displaying on screen whereas at the same time this ICC profile in the Output Intent does not trigger any unwanted further color conversions.
  • Note: Please be aware that only ICC profiles of type 'prtr' (output profiles) are allowed in an Output Intent for PDF/X files. Embedding for example an sRGB profile (which is a 'mntr' or display profile) in a PDF/X Output Intent will make it impossible to turn that file into a valid PDF/X file (or make it an invalid PDF/X file if it already had been a PDF/X file).

Assumed profiles

With this list you can specify the default profiles that will be used as the object's source profile if the object does not have a source profile. In any case, this will only have effect if "Convert to destination" or "Convert only alternate color space to destination" is chosen in the Conversion list under "Conversion settings". It is necessary to have valid ICC profiles specified for all color spaces. Selecting a predefined Adobe color setting here will change the settings for the color spaces automatically.

  • Note: If you import this Fixup and the used ICC profiles are not present on your system, you need to execute the Fixup once (otherwise the ICC profile may be displayed in "(...)", as it is not present on the current system yet).

RGB

List of available ICC profiles to be assumed for uncalibrated RGB colors.

CMYK

List of available ICC profiles to be assumed for uncalibrated CMYK colors.

Grayscale

List of available ICC profiles to be assumed for uncalibrated grayscale col­ors.

Output Intent takes precedence over assumed profile

If there is an Output Intent embedded in the processed file, the selected profile for the color space defined by the assumed Profile will be ignored and instead the settings will be adapted to the Output Intent profile.

Use black point compensation

If this checkbox is activated, black point compensation will be used for color conversion using the relative colorimetric rendering intent.

Preserve black objects

If this checkbox is activated, color definitions using just the black channel will remain black. Furthermore, RGB and Lab color definitions for gray will get converted to Black only where applicable. For more information about the treatment of black objects please read the article: Processing black objects.

2. Conversion settings

You can define additional conversion settings for the various color spaces or object types by using the "Add setting" button (1). Since pdfToolbox 14 it is also possible to duplicate the respective set of configured parameters with the “Duplicate setting” button (2).

Objects

Here you can limit the execution of color conversion to a certain object type defined by a Check.

using

List of color spaces for which the defined conversion settings should be applied.

Conversion

You can choose one of the following options:

Decalibrate

Removes the source profile from a calibrated color space.

Note:

When pdfToolbox decalibrates ICCbased CMYK it will also disable the Overprint Mode (OPM) for the objects (if active beforehand). Background is that the OPM parameter has no effect on ICCbased CMYK and therefore disabling it avoids unexpected changes.

This approach has one limitation: If source profile and destination profile for an ICCbased CMYK object are identical the OPM parameter may actually have an effect. In such cases the above approach is not ideal and may require to establish OPM after the operation again.

Convert to destination

Objects are converted to the destination color space as specified by the destination settings.

Decalibrate, then convert

Removes the source profile from a calibrated color space first and converts the resulting, uncalibrated color into the destination color space.

Convert only alternate color space to destination

Only the alternate color space of spot colors is converted to the destina­tion color space as specified by the destination settings.

Tag with ICC profile

Tags an object with the ICC profile of the destination if the source color space matches.

Do not convert

Objects will not be converted. This might be useful if you want to exclude a specific object type or color space from the color conversion.

Rendering intent

This list lets you define which Rendering Intent is used for a color conversion:

  • Use rendering intent from document
  • Perceptual
  • Relative colorimetric
  • Absolute colorimetric
  • Saturation

Note:

  • If there is no Rendering Intent explicitely defined in the PDF the default is Relative colorimetric.
  • The setting has no effect for the conversion options "Decalibrate" and "Tag with ICC profile".

3. Advanced settings

The regular ICC based color conversion is extended by some useful options. This includes for example obtainment of pure black, recognition of RGB black or adaption of tone value increase. For more information about the treatment of black objects please read the article: Convert colors: Advanced settings.

Handling of process colors in Separation and Device N

As soon as you run a "Convert colors" Fixup, the alternate values of the fol­lowing separation color spaces will be adapted automatically, to prevent problems in the output process:

Source
 Destination
Separation/DeviceN Black
 0% DeviceGray
Separation/DeviceN Cyan
 100/0/0/0 DeviceCMYK
Separation/DeviceN Magenta
 0/100/0/0 DeviceCMYK
Separation/DeviceN Yellow
 0/0/100/0 DeviceCMYK
Separation "All"
 0% DeviceGray
Separation “None"
 100% DeviceGray