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HELIOS ImageServer User manual |
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ImageServer 2.5 supports a wide range of image formats and color spaces. As default, the CMYK color space is used for output. This section describes how to setup a printer queue for an alternative RGB workflow and explains possible pitfalls.
We received several customer requests for supporting an alternative workflow using RGB images and composite output without color matching. This is not possible using ImageServer 2.5 with default color matching settings.
Such a workflow may be useful, e.g. for creating PDF files with unchanged composite images (RGB, CMKY, or Lab-based). The images must be tagged with an ICC profile and the output queue must not have any ICC profiles attached to make sure that no color matching occurs during output.
To change the default behavior of ImageServer 2.5 for a specific queue the following commands must be performed:
# cd /usr/local/helios/bin
# prefvalue -k 'Printers/<printer queue>
/CompositeColorspace' -t str "None"
Change "printer queue" above to the name of the queue you want to change. The queue name has to be exactly the same name as displayed in the Printer Name: field of EtherShare Admin's Printers configuration window.
Important: Choose the queue you want to change carefully because all composite images (regardless whether they are RGB, CMYK or Lab) will be sent to the output device without any color matching. These settings do make sense for example on a Create PDF queue because the Distiller is able to handle all composite color spaces.
Note: The output result of such a modified queue may also depend on the used image type (e.g. EPS or TIFF) and on the application used! An application may change RGB image data while printing. Therefore only low-res images (layouts) should be used because these are CMYK-based. We suggest to test the workflow carefully for such potential flaws prior to use these new settings in a production environment.
# cd /usr/local/helios/bin
# prefvalue -k 'Printers/<printer queue>/ProcessInks' -t
strlist "Cyan","Magenta","Yellow","Black",
"Orange","Green"
Additionally, the order of the specified colors must match the order in the used Hexachrome® profile. If the order in the profile is different, modify the above mentioned command line according to the order in the profile.
Note: Please note that an inaccurately set preference may lead to faulty results! Read more about the usage of "prefvalue" in the HELIOS Base manual.
-> Allocate the Hexachrome® profile as printer profile to the specific queue you want to use. Do not allocate a proof profile!
To enforce a Hexachrome® color separation, the
"ForceHexachrome.eps" has to be placed in each page of the document (see below).
If you are using PrintPreview, the spot colors "Green" and "Orange" have to be defined in EtherShare Admin's Spot Color editor. This enables PrintPreview to create a correct composite preview.
All placed images have to be "tagged" with an ICC profile, or must be allocated a default profile per folder/volume.
The HELIOS CD-ROM includes a file named "ForceHexachrome.eps" in the sample-images folder. This file defines six process colors: Cyan, Magenta, Yellow, Black, Green and Orange and needs to be placed in the layout application to enforce the six-channel separation output for printing. The file does not contain printable data.
| © 2002 HELIOS Software GmbH |
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