Start > Sequence Templates - Proofing > "PageProof" Sequence Template > "Color Conversion" option
You enable Heidelberg's color management with this option. Color settings are taken from the documents if this option is not enabled. Normally, the color management settings of the "Rendering" option are used for proofing (see "Proof Color Management" Section).
"Proof Color Management " in the "Rendering" option matches the color output to the specific properties of the proofer and, if necessary, simulates inking of the printing material used in the final output, whereas in the "Color Conversion" option color management is applied equally to screening and proofing. In a proofing sequence, you should enable the "Color Conversion" option only if you need a media-neutral output process.
When processing color data from their creation (scanner, digital photography, graphics applications) up to output, there are many places that are the cause that the printed result is not what you expected because of the various characteristics of the devices or applications concerned. The colors are often incorrectly printed or are located in an unsuitable color space, and a time-consuming adjustment process is required to correct the colors.
To avoid the subsequent correction of incorrectly reproduced colors, the color management tool may be of assistance. Color management runs through the whole process path of the prepress and press workflow. A color management can therefore only provide correct results when the corresponding tools are correctly applied at every level of the workflow. This requires that the devices, applications and operating systems involved in the workflow support color management and are correctly set up.
The goal of Color Management is to standardize the color reproduction of digital image data over the entire editing process. Color space conversion was introduced to achieve a standardized color representation. Color space conversion basically matches the image or graphic data from the creator color space (e.g. color space of a digital camera) to the color space of the output device or process (e.g. color space of a color printer).
The diagram below shows the basic principle of a color space conversion:
•First of all, the data are in the color space of the input device (scanner, digital camera, etc.).
•The data are converted to the device-independent profile connection space (CIEL*a*b* color space) when the device ICC profile is enabled. The abbreviation "CIE" stands for "Commission Internationale de l'Eclairage". L*a*b* is an abstract name for a certain 3-dimensional color space model: one axis represents the brightness (L = "Luminescence") and the other two axes represent the different color values (a = red - green, b = yellow - blue), where a and b can have positive and negative values.
•A suitable ICC profile for the output device is activated for the output. This profile matches the image data to the output device (monitor, printer) or output process (offset printing). As a result of this, the image data are again device-specific.
The ICC profiles can be present in different ways during gamut mapping:
•Embedded ICC profiles: The ICC profiles are contained in the document file and are used during the respective transformation steps.
•ICC profiles that are not embedded: The ICC profiles must be available as separate files on the Prinect Server. They are selected in the Color Management settings and then used for conversion.
The Color Conversion engine of the Prinect Manager and the Prinect Color Editor software (Acrobat plug-in) support Heidelberg's Color Management. The Prinect Manager lets you use Heidelberg Color Management also for proofing.
In this tab, you can define general settings to prepare your documents for color conversion.
"Add Settings as PDF Comment" option
The settings that were used for color conversion are added as PDF comments to the edited documents when this option is enabled.
"Remove traps" option
All the traps (spreading lines) in the documents are removed if this option is enabled. Documents should not have any trap lines to use Color Management properly. You can apply trapping again in a later step. This option has no effect if there are no trap lines in the documents. For that reason, we recommend that you always leave this option enabled.
"Compress Processed Images" option
During color conversion, all the images in the documents are decompressed. The processed images are compressed again afterwards with this option. The following compression modes are available:
•ZIP (lossless)
ZIP is well suited for images with large, single-color areas or repeat patterns, e.g. screen shots and simple images.
•JPEG (lossy)
JPEG is suited to grayscale and color images as well as photos with shades (blends). You can have loss of data with JPEG compression, for example, image data are removed and the image quality may be impaired.
Because JPEG compression removes image data, the compressed files are really noticeably smaller than the ZIP-compressed files.
•Automatic (JPEG, ZIP, None)
With "Automatic (JPEG; ZIP, None"), compression depends on the original image compression.
Compression reduces the file size of the PDF documents.