3.1 Backward compatibility
ImageServer supports backward compatibility to EPSF and TIFF layout files that have been generated by previous ImageSevrer versions.
EtherShare OPI 1.x will not be able to handle and understand layout files generated by the new ImageServer version, but ImageServer 2.5 will (with the exception of the new features and the new supported file formats, e.g. JPEG2000 and JBIG2).
Please note that if you are using EPSF layout files which were generated by EtherShare OPI version 2.1 or earlier, downsampling, color matching and other new features will not be supported when you print separations. In that case, you have to generate new layouts from the high-resolution original images and thus create layout files that can be subjected to all features available in the new program version. You may use the HELIOS "touch" program for regenerating layouts (detailed instructions are given in
5.6 "Refreshing layouts using the "touch" program"), or the HELIOS "opitouch" UNIX command (see
6.3 "opitouch").
3.2 About images, color modes, file formats, and compression
This section provides an overview of ImageServer supported file formats, color spaces, and compression options for layout file generation. It is equally applicable to image conversion using ImageServer Script Server.
An image file is defined by its file format. In addition to that, it contains information about its color mode and the mode of compression. These three characteristics depend on one another and may not be combined arbitrarily. An example is given in the following illustration.
Fig. 2: The characteristics that define a given image file
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Fig.
2 for example shows a Photoshop CMYK image in the Scitex CT format, which cannot be compressed (options that are not available are grayed out in the illustration).
Important: Please note that some file formats are already compressed (e.g. JPEG).
In the following, we will-
- -give you a complete list of the file formats that are supported by ImageServer
- -describe the advantages/disadvantages of the formats
- -discuss the different modes of compression
3.2.2 64-bit file offset support
ImageServer UB handles file sizes up to 64-bit, which equals 8.3 million TB (
Terabyte). The old 32-bit support can only handle files up to 2 GB. This is important because image files today can easily exceed 2 GB.
3.2.3 Supported file formats
ImageServer provides OPI facilities and, in addition, contains built-in color management features. The software accepts different file formats for the generation of (low-resolution) layout files and it supports various file formats for color matching. Please note that some file formats in connection with specific color modes allow the generation of layout files, but do not allow color matching.
Table 1 lists all supported file formats for the generation of layout files (and their possible color modes), whereas
Table 2 only lists those file format/color mode combinations that allow color matching. If you want to achieve predictable color results on your printouts, you should select for your image files one of the file formats listed in
Table 2.
Table 3 gives an overview of the image file formats that are supported by ImageServer UB.
Table 1: High-resolution file formats that are supported by ImageServer UB
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Bilevel, Grayscale, Indexed, RGB, CMYK, CIE Lab, Multichannel * (e.g. Hexachrome ®), YCbCr *
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EPSF raster- and object-based images
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Bilevel, Grayscale, Indexed, RGB, CMYK, CIE Lab, Spot, Multitones *
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Bilevel, Grayscale, Indexed, RGB
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Grayscale, RGB, CMYK, CIE Lab, YCbCr *
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Grayscale, RGB, CMYK, CIE Lab, YCbCr *
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Bilevel, Grayscale, Indexed, RGB, CMYK, CIE Lab, Spot, Multichannel *
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Bilevel, Grayscale, Indexed, RGB
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Bilevel, Grayscale, Indexed, RGB, CMYK, CIE Lab, Spot, Multichannel *
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CMYK, Spot, Multichannel *
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Currently read-only support ** PDF HandShake option
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Table 2: File format/color mode combinations that are supported for color matching
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RGB, CMYK, CIE Lab, Multichannel * (e.g. Hexachrome ®), YCbCr *
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RGB, CMYK, CIE Lab, YCbCr *
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RGB, CMYK, CIE Lab, YCbCr *
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RGB, CMYK, CIE Lab, Multichannel *
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RGB, CMYK, CIE Lab, Multichannel *
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1
Currently read-only support ** PDF HandShake option
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Table 3: File formats, image types and suffixes
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Encapsulated PostScript File
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Binary Encapsulated PostScript File
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Scitex CT Handshake Format
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Adobe Photoshop Version 2.0 Format
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Adobe Photoshop Version 2.5 Format
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Adobe Photoshop Version 3.0 Format
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Adobe Photoshop Version 2.0 Format
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Macintosh Picture format Version 1
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Macintosh Picture format Version 2
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Macintosh Custom Icon Family Format
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Adobe Path Resource Format
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Portable Network Graphics File Format
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HELIOS Document Preview (XPPV)
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Portable Document Format Version 1.1
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Portable Document Format Version 1.2
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3.2.4 File format characteristics
Before you save an image in an image processing application (or scan system), you should make a decision on the file format you want to choose. The advantages and disadvantages of the different file formats are described below.
Important: Again, the file formats have to be judged from different points of view. Some characteristics of a given file format may be advantageous in general, and for OPI processes, but - at the same time - disadvantageous with regard to color matching!
The format you choose for an original high-resolution image file determines the format of the automatically generated layout file. Please refer to
3.2.6 "File formats of OPI-generated layout files" for explanations on the different layout file formats.
- Advantages
- Many scan systems and image processing applications can generate TIFF files. Thus, they become - in principle - OPI-compatible
- TIFF files can be edited by all popular image processing applications
- TIFF files are independent of the output device
- For TIFF files, portions of an image can be sent to the output device (in case you have selected only a specific part of the image in the layout application)
- The resolution of TIFF files can be reduced during output and thereby adapted to low-resolution output devices
- The TIFF format supports many color modes
- A clipping path that has been defined in image processing applications is preserved for printing (for details and exceptions see 3.3.3 "Image paths and clipping paths")
- Advantages
- Disadvantages
- Many image processing applications cannot re-edit EPSF files
- Complete images are sent to the output device, even if you have selected only parts of the images in the layout application
- When printing separations, the entire EPSF image must be sent to the RIP four times (ImageServer solves this problem)
- The resolution of an EPSF image remains unchanged (e.g. 1200 dpi) even if you are printing to an output device that only allows lower resolutions (e.g. 300 dpi). Thus, printing may become very slow (ImageServer solves this problem via optional downsampling)
- Advantages
- Smaller file size
- Files can be zoomed without any loss in quality
- Disadvantages
- There are few image processing applications that can read object-based EPSF files
- Advantages
- PICT files are small and preserve masks or paths
- Disadvantages
- The format is meant for Macintosh platforms only
- Advantages
- Files are highly-compressed and thus become very small
- Disadvantages
- The mode of compression affects the quality of the images.Therefore, the JPEG format should not be used for printing purposes.
- Advantages
- Provides a higher compression rate than JPEG due to "Wavelet" compression
- Unlike JPEG, JPEG2000 allows lossless compression methods
- Supports additional meta data and XML specifications within the JPEG2000 file
- Disadvantages
- Limited support (few applications support JPEG2000)
- Advantages
- Very high compression rate, which exceeds CCITT
- Both lossy and lossless compression possible
- Halftoning of Grayscale images
- Disadvantages
- Limited support (few encoders can write the JBIG2 image format)
- Advantages
- Scitex CT files are pre-separated. Thus, they are already prepared for printing separations
- Disadvantages
- Pre-separation is disadvantageous for color matching, because the separation plates are created for an image that has not yet been subjected to the matching process
- This format does not allow any mode of compression.
- The format is only available for Grayscale and CMYK images
- Advantages
- The Photoshop Native format supports all color modes
- For multi-layer images, the layer information is preserved
- Disadvantages
- Advantages (compared to standard EPSF files)
- ICS files are pre-separated. Thus, they are already prepared for printing separations
- Disadvantages
- The format is available only for CMYK images and requires Linotype-Hell applications
- See DCS 1
- Advantages
- Disadvantages
- No CMYK, Lab and clipping path support
- Advantages
- Supported by web browsers
- No license fees required
- Supports transparent clipping paths (implemented via alpha channels)
- Disadvantages
- Advantages (compared to standard EPSF files)
- DCS 1 files are pre-separated and are composed of several files containing the EPSF separation plates for cyan, magenta, yellow, and black. Thus, for a given color, only the file that describes this specific separation is sent to the RIP (if you are working with the EPSF format, you only have one file that contains the complete image description. This large file has to be sent to the RIP four times)
- Disadvantages
- Pre-separation is disadvantageous for color matching, because the separation plates are created for an image that has not yet been subjected to the matching process
- Composite printers, usually, are unable to handle the four EPSF separation plates at a time and thus cannot produce a composite printout
- Advantages (compared to the DCS 1 format)
- They contain the EPSF separation plates for cyan, magenta, yellow, and black, and - optionally - additional spot colors, in only one file
- Disadvantages
- Advantages
- Allows storing illustrations, text, and images in one file
- Supports several color spaces like RGB, CMYK, or LAB
- Supports several compression modes such as JPEG, ZIP, CCITT, JBIG2
- Supports several types of fonts (PostScript and TrueType)
- Editing is possible using Acrobat
- Disadvantages
- The various content types can present printing problems (PDF HandShake solves these problems)
3.2.5 Supported modes of compression
ImageServer supports several file formats for the generation of layout files, even if the data contained in these files has been subjected to compression. The original high-resolution files remain compressed, but usually do not pass on the compression to the layout files. If you want the layout files to be compressed as well, you may use HELIOS Admin, or the respective UNIX parameters (see
4.2 "ImageServer settings" and
6.2 "layout" for details).
Table 4 lists various modes of compression supported by ImageServer UB and indicates whether or not they can be applied to the different file formats.
Table 4: Modes of compression and their relation to different file formats
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1
Currently read-only support ** PDF HandShake option
a This mode of compression is allowed but will cause restrictions: raster-based data is no longer recognized by ImageServer.
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3.2.6 File formats of OPI-generated layout files
The layout files that are generated by the OPI software are either EPSF or TIFF, depending on the color mode and file format of the high-resolution original image.
The OPI server generates EPSF layout files if
- the high-resolution original image is an EPSF, ICS, PDF, or DCS image or
- the high-resolution original image is not an EPSF, ICS, PDF, or DCS image, but shows one of the following characteristics:
- it contains color channels that do not belong to the selected color mode
- it is a Multichannel image
- it contains a clipping path
TIFF layout files are generated of every high-resolution original image that
- does not contain a clipping path
- is not an EPSF, PDF, ICS, or DCS image
EPSF versus TIFF
layout files
In the following, we briefly discuss the differences between EPSF and TIFF layout files. Knowing these differences can help you decide which layout file format you want to use. (You may then select the color mode and file format for your high-resolution original images and thereby indirectly determine the desired layout file format.)
There are mainly two aspects that make up the difference between EPSF and TIFF layout files:
- EPSF files do not allow source cropping. If you crop an image in a layout application, this does not reduce the amount of data that is sent to the print server, because you can include only complete EPSF layout files into a print job. This is different if you are using TIFF layout files and then crop the images. In that case, the print job will only contain the data that describes the visible part of the image.
- Many applications - even on different platforms - are able to place EPSF layout images. Thus, these applications automatically become (quasi-)OPI-compatible (see Layout applications in 3.3.1 "OPI-compatible applications").
Note: EPSF files are not identical for Macintosh and Windows computers. In fact, PC-EPSF layout files may cause problems if the high-resolution original images include a clipping path (see also 3.3.3 "Image paths and clipping paths").
Other layout file formats?
In most cases, it is convenient and sensible to accept the default EPSF or TIFF layout file format. Nevertheless, you may as well choose any other format for your layout files.
5.3 "Defining folder specific OPI settings" explains how to set custom settings on a "per volume" or "per folder" basis.
Color modes for
layout images
The color modes of the high-resolution originals are not passed on to the layouts. By default, layout images are Euroscale- or SWOP-CMYK, to allow the layout applications to print separations. In special situations, you may also select the RGB or Lab color mode for layout images (see
Layout Color in
4.2 "ImageServer settings").
3.3 About applications, OPI comments, and modifications
3.3.1 OPI-compatible applications
The ImageServer software requires two types of OPI-compatible applications, namely:
- Scan systems, image processing applications, or similar programs that are able to generate one of the image file formats which allow the generation of layout files
- Layout applications which allow importing layout files and are able to generate OPI comments
Image
processing
applications
Most scan systems and image processing applications are OPI-compatible as far as the "input" side is concerned. They all offer the possibility of creating at least one or two file formats that are supported by ImageServer for the generation of layout files and for color matching (e.g. TIFF-RGB or raster-based EPSF-CIE-Lab). One of the most frequently used image processing applications is Adobe Photoshop - ImageServer supports the Photoshop Native format.
Strictly speaking, OPI-compatible layout applications have to meet two different demands: they have to be able to import/place layout images and they have to be able to generate OPI comments according to the Adobe OPI standard and place these comments into the PostScript that is generated for each print job.
There is, however, one exception from this rule: layout applications that are able to import EPSF layout files are quasi-OPI-compatible, even if they do not generate OPI comments. This is due to the characteristics of EPSF layout files which simply do not allow applications to modify their contents. If an EPSF layout file already contains OPI comments - e.g. a reference to the location of the original high-resolution image file - these comments are preserved and passed on to the PostScript file.
Note: Some layout applications that are fully OPI-compatible also offer OPI options in their print dialogs, namely "Omit TIFF" and "Omit TIFF & EPS" , and thus provide additional means of speeding up print jobs when working with OPI. Details about the "Omit -" options are given in 5.7 "OPI print options - include or omit images".
The most frequently used layout applications that are - in principle - fully OPI-compatible are listed in
Table 5.
Table 5: OPI-compatible layout applications
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Other applications like TrapWise, PressWise, CorelDraw, Illustrator, FrameMaker, Word and Ventura Publisher may also be involved in the process of creating documents that include text and images. Strictly speaking, they were not designed for layout purposes in prepress environments. These applications are - if at all - only quasi-OPI-compatible,when they use EPSF layout files.
The mentioned restrictions are also applicable to layout applications for UNIX systems. Most of these applications (e.g. FrameMaker for UNIX) are able to import EPSF layout files, and thus can be used with ImageServer.
3.3.2 Supported image modifications and
OPI comments
Different layout applications provide different features for image modifications. Depending on your application, you can e.g.
place, move, scale, rotate, skew, reflect, tint, or
crop your images, and apply a
clipping path, or overprinting. All these modifications are supported by ImageServer and are automatically applied to the high-resolution original images during printing.
Important: Transparency definitions for grayscale and color images are the only modifications that are not supported by ImageServer, due to limitations in the OPI specifications. You may overcome this limitation with the "pdfresolve" tool, which is described in the PDF HandShake manual.
If you print from a layout application, the OPI server requires different information about the images that are included in the document. There are several OPI PostScript comments that contribute to a complete image description. Some comments only serve to clearly identify the high-resolution image; others are used to describe the modifications that have been applied to the layout.
For example, the comments "%ALDImage Dimensions" and "%ALDImagePosition" define the dimensions and the position of an image, and thus may also include information about whether you have moved or scaled the layout image.
3.3.3 Image paths and clipping paths
In Photoshop, the outline of a selected area can be saved as a vector outline, or
path. Multiple paths can be created and saved with the file. One of the paths can also be selected as a
clipping path. A clipping path can be activated to mask part of an image, so that only the desired portion is seen in the printout. Some page layout programs can recognize and utilize these paths. However, the behavior varies depending upon the program and file format. For example, some applications have poor support for TIFF files containing paths, while others have excellent support. ImageServer can be set to produce layout files with the desired path properties for your specific page layout programs and objectives.
Multiple Photoshop clipping paths
ImageServer now supports multiple clipping paths, any one of which may also be designated as the active clipping path. Multiple paths are migrated into layout and converted files. Photoshop clipping paths can be exported/imported into existing files, so customers can re-use the images and use different clipping paths for different jobs (see
ImportMask in
6.2.8 "Options for image conversion" and
6.2.11 "Options for tagging"). In layout applications such as QuarkXPress or InDesign, it is possible to select a defined path and make it the active clipping path.
TIFF files with clipping paths
Clipping paths can be saved within TIFF images in an image processing application. Even though the image will print correctly and the clipping path will be applied, some applications cannot display a TIFF clipping path, and hence are unable to properly use features such as text "Runaround". Therefore, by default, ImageServer generates EPSF layout images of TIFF hi-res files that contain a clipping path. Layout applications can then properly display and use the clipping path (unless your system creates PC-EPSF layouts).
If your layout application, e.g. QuarkXPress 4.1-6 or InDesign 2/CS, does support the TIFF clipping path feature then you can use either EPSF or TIFF layout images. Some applications also have the capability to add or modify the image clipping path in TIFF files. If you wish to take advantage of this feature, layout images should be generated in TIFF format (see
5.3 "Defining folder specific OPI settings"). TIFF layout images will always inherit all paths from the high-resolution image.
PC-EPSF files with clipping paths
Unlike Macintosh-EPSF files, PC-EPSF files contain a TIFF screen preview of the respective image (instead of a PICT screen preview).
The layout application uses the PC-EPSF included TIFF screen preview for the monitor display. ImageServer defines the value white to the area of the rectangle that has been clipped away, so that applications can apply the "Runaround" feature after placing the layout image. Thus, if you generate PC-EPSF layout files, even if the screen preview image has a clipping path with a shape other than a rectangle, it will be printed correctly.
Note: For the generation of PC-EPSF layouts see
4.3 "Volume settings".
EPS layout files and clipping paths
Some layout applications lack full support for TIFF images containing a clipping path. For these applications, EPS layout images should be used (the server default). In this case, you need to specify whether the server image replacement should use the clipping path applied by the image processing application, or the path applied by the page layout application. See
3.3.4 "Application clipping paths" for details.
3.3.4 Application clipping paths
A bitmap image file that already contains clipping path information and then has path changes applied in a layout program, may cause interferences and lead to unwanted results. HELIOS Admin offers an option (see checkbox
Ignore Mask for Bitmap Images During Output in Fig.
3 below) that makes the server ignore existing masks for bitmap images so a new clipping path can be defined from within the layout application (QuarkXPress, InDesign, etc.). This option can also be set for individual folders via folder naming syntax (see
5.3 "Defining folder specific OPI settings").
Fig. 3: HELIOS Admin
OPI Server Settings dialog
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Note: Multiple Photoshop clipping paths are migrated into layout and converted files. Photoshop clipping paths can be exported/imported into existing files, so customers can re-use the images and use different clipping paths for different jobs.
Table 6 gives an overview on the compatibility of layout software programs and the used layout file formats which have application paths included.
Table 6: Application path compatibility
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EPS Layout with default application path
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3.3.5 Additional channels in bitmap images
ImageServer recognizes and supports additional channels (e.g. Hexachrome
®, spot colors, or alpha channels). At present, ImageServer will use all additional channels as spot color channels.
It is often required to ignore additional channels and use the default printing channels, e.g. CMYK, RGB, CIE-Lab. Many layout applications ignore additional channels in order to be compatible with the printout. Printing from these applications, ImageServer can ignore additional channels (see
Ignore Additional Channels for Bitmap Images in Fig.
3) server-wide or enable/disable this setting on a folder tree (see
5.3 "Defining folder specific OPI settings").
PostScript
Level 1&2, PostScript 3
ImageServer requires PostScript output devices for printing. There are three types of PostScript RIPs: Level 1, Level 2, and PostScript 3 compatible devices.
The Level 2 and PostScript 3 specifications are follow-ups to the Level 1 specification and provide many more features, as e.g. support for different color spaces such as CMYK, RGB and CIE-based color spaces, and provisions for color matching and transformations into CMYK.
Different printers may behave differently and provide different features. PPD files contain comprehensive printer descriptions - with the supported PostScript level being only one aspect. ImageServer (just like any application) refers to the PPD file to get information about the features of the output device. So, for high-quality printouts, always make sure that you have activated a PPD file that properly corresponds to your current output device. For details, see the EtherShare documentation.
Are PostScript levels relevant to ImageServer?
Usually, if you are printing with ImageServer, our software takes care about the separation into CMYK. The separation modules of the RIP are not required. Thus, print jobs do not depend on the final output device. It does not make any difference whether you are using a Level 1, Level 2, or PostScript 3 printer.
It is, however, possible to leave the separation to the PostScript RIP. In that case, you have to select the Lab D65 color space as output color space (see
Default Printer Profile in
4.4 "OPI printer queue settings") and you must use a Level 2 (or PostScript 3) output device. The RIP will then be initialized with a specific CRD (
Color Rendering Dictionary) and, using this dictionary, will perform the separation into CMYK. This workflow may be sensible if you are sending your documents (e.g. a magazine) to different production sites. Your print job is not yet separated for a given output device and the Lab D65 color space is device independent. The different RIPs transform the color data into the gamut of the respective printer or press and the output results should all be identical. Please note that this workflow does not allow proof printing (see
A 2 "Colors, color matching, proof printing - basic concepts" for details about proofs).
3.5 How ImageServer modifies color modes
If you retouch an image using an image processing application, you also define a color mode for this specific image. This color mode will be preserved as far as the high-resolution original image file is concerned - but it will not be passed on to the layout file and may be changed for printing purposes, i.e. transformed into the color space of the output device.
In the following, we briefly describe how ImageServer handles or modifies color modes and thus relieves you of taking care about it.
The color mode OPI selects for printing depends on whether you print composite or separations and whether or not you have activated color matching. The color mode of the high-resolution original image does not matter, unless it is Bilevel or Grayscale - these two color modes are preserved for printing.
Note that only images which are replaced by the OPI server, and which are raster images, may be subject to color space conversion. All other images remain as they are. Whenever a color space conversion is performed, the source ICC profile associated with each image is used. In the absence of a source profile, the server defaults are used (see
4.2 "ImageServer settings" and
8.1 "ImageServer preference keys").
- Printing composite (without active color matching):
Images that are printed as rastered images are transformed into the color space that is specified (see CompositeColorspace in 8.1.5 "OPI-related printer queue preferences", A 3.1 "Preserving the original color space in composite printing", and "psresolve" in the Base manual for details).
For other images, color spaces remain as they are.
- Printing composite (if color matching is active):
For all images that are printed as rastered images, OPI uses the color space that is specified in the printer profile. For other images, color spaces remain as they are.
- Printing separations (without active color matching):
For all images that are printed as rastered images, the color space is CMYK. For other images, color spaces remain as they are.
- Printing separations (if color matching is active):
For all images that are printed as rastered images, OPI uses the color space that is specified in the printer profile. For other images, color spaces remain as they are.
Color modes for
layout images
You may select a color mode for the layout files. You can choose between CMYK, RGB, and Lab (see
Layout Color in
4.2 "ImageServer settings"). By default, OPI sets the Euroscale CMYK color space for layouts, to allow layout applications to print separations.
3.6 How ImageServer applies color matching
The settings for color matching may be different for every printer queue you have defined on your server. The ImageServer CMM (
Color Matching Module) is activated by selecting an ICC printer profile for the respective printer queue (see also
4.4 "OPI printer queue settings").
However, in some specific situations ImageServer performs color matching "behind the scenes", even though it has not been activated explicitly. These situations are described below (please remember that you must not delete the "ICC-Profiles" volume, because this would disable indirect color matching, which would entirely disable OPI).
The color matching module is active
- whenever OPI transforms an image into another color space (see also 3.5 "How ImageServer modifies color modes").
- for all Lab images, because they always have to be transformed into RGB or CMYK (unless you are working with Lab layouts and explicitly choose "Lab D65" as output profile - compare chapters 4.2 "ImageServer settings" and 4.4 "OPI printer queue settings").
- for all Multichannel images (Hexachrome®, HiFi Color, etc.). For these images, there are no standard profiles OPI can refer to. Therefore, you are forced to specify an ICC printer profile and thus activate color matching.
ImageServer needs an ICC profile on the output side (printer profile) and an ICC profile on the input side (image source profile) for proper color matching . This means that you need to tag an image profile to every high-resolution image you wish to print with predictable colors, and you have to make sure that your layouts are tagged in case you want to print layouts (see also
5.4 "Tagging images with ICC profiles").
3.7 How ImageServer finds and replaces image files
Whenever you print a document from a layout application, the OPI software has to locate and find the images that are to replace the low-resolution images you have used for layout purposes. These images, which are required for replacement, may be either high-resolution originals, or the layout files again (in case you print your documents with layouts).
If you do not use the layouts at all, but import high-resolution images into your document, there will be no image replacement for printing unless you set the
Replace Images option to
All for your current printer queue (see also
4.4 "OPI printer queue settings").
Important: If you want to use OPI from a Windows system, you should always maintain the 3-character file name extension. The extension may be any extension that is supported by Photoshop for Windows!
ImageServer offers complex finding strategies for image replacement. The software is able to locate images even after you have moved or renamed them - as long as they remain in the same server volumes.
- First of all, OPI will check the folder that contained the image file during layout generation.
- Secondly, the software will disregard the ".lay" extension and the "layouts" subfolder of the folder that contains the placed image and then check this folder.
- After that, OPI will check all image search paths you have defined using HELIOS Admin (see 4.2 "ImageServer settings"). These search paths help the OPI software trace images you have moved after layout generation.
- Finally, if a high-resolution file cannot be found with the methods described above, OPI will try to resolve, with the server desktop database, the Macintosh file ID, which has automatically been saved in the low-resolution file during layout generation. With this method, it is possible to find image files which were renamed and/or moved in the same volume (in case the EtherShare server desktop database is outdated, searching via file IDs may find the wrong image. With the "psresolve" command, you can switch off image replacement by file ID using the ImageIDsearch parameter. For details see "psresolve" in the Base manual).
Please note that the finding procedures are started automatically during printing. If you want OPI to report missing image files, you must activate the
Check Images option when setting up the print preferences (see Fig.
9 in
4.4 "OPI printer queue settings"). Missing images will then stop the print job. With
Check Images switched off, the documents will be printed, but the printouts will show blanks where images could not be found.
Note: You may use the HELIOS "Error Queue" feature to save and restart print jobs that have produced an error message..
