When converting colors in ZePrA, a distinction is made between the objects, the Document Color Space and the target color space. A queue in ZePrA processes images as well as vectors/text in PDF files. By default, the same settings are used for converting both images and vectors. CMYK, RGB, Grayscale and LAB files are processed according to the settings defined within the Images/Vectors tabs. With this approach both a source profile and a DeviceLink profile can be assigned or embedded profiles can be read. The SmartLink option available under Images/Vectors provides the ability to generate a high quality DeviceLink profile on the fly, or to use an already available DeviceLink profile when converting from source color space to target / Document Color Space.
If the Apply Embedded Profiles / Intents checkbox is enabled in the Images/Vectors tab in ZePrA for CMYK, RGB or Gray image or vector data, not only is the ICC device profile read, but also the embedded rendering intent in PDF files. The rendering intents selected under Images and Vectors are ignored for PDF files but are used when converting image data. To ensure high quality color conversion without definition losses when using the embedded rendering intent, enable Black Point Compensation under Configurations / Options.
When using Save Ink profiles, options such as rendering intents, spot colors, image quality, sharpening and calculating ink saving can be defined.
Images and Vector Main Window
Handling Image Files
Define how individual image objects in a PDF file, TIFF, JPEG, PSD and PSB are handled under Image Color Conversion. There are three conversion options for CMYK, RGB, Gray and LAB:
- No Conversion: Images are not converted
- Convert to Document Color Space: First converts the image data to the ICC device profile selected as the Document Color Space in the Document/Target tab. In the second step, the conversion settings made in the Document/Target tab are applied to the image data. This often leads to a second conversion of the image data into the target profile set under Target Color Space according to the settings.
Notes: In the PDF context, conversion to the Document Color Space is also referred to as normalizing and is a common practice. For the conversion of pure pixel data (PSD, TIFF, JPEG) the two-step conversion using Convert to Document Color Space is usually not recommended.
- To Target Color Space: Converts the image data from the source color space to the profile selected under Target Color Space without first converting it to the Document Color Space.
Files composed of grayscale images can also be converted with the Use CMYK Conversion option. The gray components will be converted with the same settings used for CMYK. If a DeviceLink conversion under CMYK has been set using SmartLink, images composed of gray will remain gray after conversion.
Using the Apply SmartLink checkbox, select the use of the DeviceLink profiles for data conversion. If a DeviceLink profile is used, the embedded CMYK profile for a PDF object is ignore and the correct DeviceLink profile is used for conversion instead. If the DeviceLink profile was calculated with the option for preserving pure primary and secondary colors, Apply SmartLink will ensure that the pure colors remain pure in CMYK objects with embedded profiles. If this feature is not enabled, direct ICC based conversion to the target profile or Document Color Spaces are performed. Pure CMYK colors are often contaminated in the process leading to problems with overprinting elements.
If embedded profiles are present in the images, the Apply Embedded Profiles / Intents option ensures they are given preference over the selected profile in ZePrA. In PDF files, the embedded rendering intent is used at the same time as the profiles, whereas the rendering intent set in ZePrA is used for converting TIFF, JPEG and PSD images.
The rendering intent chosen is crucial for optimal conversion of the data. Besides the standard conversion methods, ZePrA includes 5 rendering intents to choose from to ensure harmonious color conversion.
When using an embedded ICC device profiles, the rendering intent is specific in ZePrA is not applied and the rendering intent embedded in the PDF file is applied instead. Since the embedded rendering intent in PDF files can be set to relative colorimetric, Black Point Compensation should be selected in the Configurations / Options tab.
Enabling the Ignore PDF Rendering Intents checkbox in the Options tab will allow specification of a rendering intent in ZePrA. Whether the target profile is embedded after conversion has been completed is dependent on the settings in the Target Color Space and PDF tabs.
Vector Color Conversion
By default, the same settings are used for processing both images and vectors. (link Read more on images / vectors). Under Options, settings for conversion of text and pure black vector can be found. To achieve high quality color conversion, DeviceLink profiles should be used. When CMYK conversion in ZePrA is performed by conversion with ICC source and target profiles, it is possible to completely exclude vector graphics from color management by enabling the Don’t Convert option. If PDF files contain flattened transparencies, most likely the pixel and vector data of the same color will directly meet therefore the basic setting in ZePrA always converts pixel images and vector graphics the same way. Color differences between adjoining pixels and vector objects of the same color are avoidable by using the Convert Like Images setting.