Flattening Settings
The default settings are recommended for final press output and for high-quality proofs.
Generally, line art and text is printed at a higher resolution than images or filled objects. It is recommended to preserve overprint black for vector/text elements, because it avoids the risk of a chromatic composition of black vector and text elements during the color management step.
| Options | Description |
|---|---|
| Raster/Vector Balance |
Specifies the amount of vector information in the PDF that will be preserved during flattening. Higher settings preserve more vector objects, while lower settings rasterize more vector objects. Intermediate settings preserve simple areas in vector form and rasterize only complex ones. If set to 0, all objects will be rasterized, that is, the output PDF will contain only image data, no vector and text objects. If set to 100, the Flattener will try to preserve all vector/text elements. (Some objects, however, might need to be rasterized despite the balance being set to full vector.) In the process of rasterizing, vector/text objects are rasterized according to the resolution defined under Line Art and Text Resolution. Other transparent objects are rasterized according to the resolution defined under Gradient and Mesh Resolution. Transparent objects overlapping with images are rasterized according to the resolution of the underlying image (that is, the resolution settings are ignored for such objects), which helps to avoid stitching problems and edges at the border between the two objects. You can reduce the Raster/Vector Balance to reduce the complexity of the flattened file. If the input PDF contains complex transparent artwork, lowering the Raster/Vector Balance can reduce the file size of the output file. Reducing the Raster/Vector Balance usually reduces processing times. For digital printing a value of 90% is recommended to get a good performance. |
| Line Art and Text Resolution | According to the Raster/Vector Balance, vector/text objects are rasterized to the specified resolution. GMG ColorServer supports a maximum of 2400 dpi for both line art and gradient mesh. The resolution affects the precision of intersections when flattened. Line Art and Text Resolution should generally be set to 600–1200 dpi to provide high-quality rasterization, especially on serif or small point sized type. |
| Gradient and Mesh Resolution | Same as Line Art And Text Resolution, but for gradient and mesh objects. If you use GMG ColorServer also for image resampling, it might be safest to use the same resolution for rasterization of gradient and mesh objects and for resampling the images. This helps to avoid stitching problems and edges at the border between two objects. |
| Compression Settings for Flattener-Generated Images |
Determines how images affected by flattening are encoded. Depending on the complexity of a PDF, flattening can significantly increase your file size. To keep the file size down and tie up valuable processing resources, you can compress your files into a ZIP or JPEG format. The compression is only applied to objects generated by way of rasterizing, not to images already existent in the input file. JPEG is a lossy compression method resulting in a tradeoff between storage size and image quality. As JPEG compression eliminates data from an image, it can generally achieve a smaller file size than ZIP compression. The quality level is automatically selected by the flattener. |
| Transparency Blend Space | This setting defines which output color space will be used if two transparent elements with different color space need to be merged. If you select Default, the output color space from the Normalization template will be used. |
| Convert All Text to Outlines | Converts all type objects (point type, area type, and path type) to outlines (i. e. vector objects) and discards all type glyph information (whether the type interacts with transparency or not). This option is not available if the Raster/Vector Balance is set to 0 (because all objects are rasterized, including text). Convert All Text to Outlines ensures that the width of text stays consistent during flattening. It can eliminate flattening artifacts that might be apparent on-screen and when printing to lower resolution output devices such as desktop printers. For example, with this option deselected, some type may be converted to outlines, while other type remains unaffected. On low resolution output devices, the outlined type may appear heavier than the unaffected type. Note that Convert All Text to Outlines will cause small fonts to appear slightly thicker on the screen or when printed on lower resolution printers. It does not affect the quality of the type printed on high-resolution printers or imagesetters. Convert All Text to Outlines can also help to avoid RIP problems with True Type Fonts in the imagesetter. |
| Convert All Strokes to Outlines | Converts all strokes to simple filled paths (whether the strokes interact with transparency or not). This option is not available if the Raster/Vector Balance is set to 0 (because all objects are rasterized, including strokes). Convert All Strokes to Outlines ensures that the width of strokes stays consistent during flattening. It can eliminate flattening artifacts that might be apparent on-screen and when printing to lower resolution output devices such as desktop printers. Note that enabling this option causes thin strokes to appear slightly thicker and may degrade flattening performance. |
| Clip Complex Regions | Ensures that the boundaries between vector artwork and rasterized artwork fall along object paths. This option is not available if the Raster/Vector Balance is either set to 0 or 100, because complex regions will only be created during flattening if some part of an object is rasterized and another is not. Clip Complex Regions reduces stitching artifacts that might result when part of an object is rasterized while another part of the object remains in vector form by creating clipping paths around these parts of a transparent design. However, selecting this option may result in paths that are too complex for the printer or imagesetter to handle. |
| Allow Shading Output | If you enable this setting, shadings are not converted to images, but remain shadings in the output. |
| Preserve Overprint > All Colors | All objects with the overprint attribute are not flattened. The overprint attribute is not resolved. For most print business applications, using this option is not recommended, as there might be different interpretations of the overprint attribute by different imagesetters. This option is not available if the Raster/Vector Balance is set to 0 (because all objects are rasterized, including overprinting objects). |
| Preserve Overprint > Black Only | Objects containing only K channel information are not flattened. The overprint attribute is not resolved. For most print business applications, using this option is recommended for vector/text, because it avoids the risk of a chromatic composition of black elements during the color management step, which could in turn lead to registration problems. Even if the Raster/Vector Balance is set to 0, black vector/text objects with the overprint attribute are not flattened or rasterized. |
| Preserve Single Channel Layers | A single channel layer is a PDF layer producing only a single plate in an imagesetter. For example, a single channel layer contains only 100% black or grayscale objects, or spot color objects. PDFs with single channel layers might be used for multi-language support: If all other contents are the same across all languages, the language can be changed by replacing only one plate (with the text) during the printing process. If the option is selected, single channel layers are not normalized, not flattened, not color managed, not sharpened, and not resampled. In other words, single channel layers are not processed at all. |
| Cancel Job when Flattening exceeds... | Enable this option if you want complex PDF jobs automatically to be canceled if they exceed the set time limit during flattening. The default time limit is set to 30 minutes. However, we do not recommend that you set the time limit to less than 20 minutes, as this is a normal processing time for larger jobs with flattening. |
| Restart Flattening by Rasterizing All Objects (Generate Warning) | This option is only available if you have the Cancel Job when Flattening exceeds... checkbox ticked. If you activate it, you will receive a warning message if a flattening job was canceled after it exceeded the set time limit. Additionally, the job will automatically be restarted and processed with 100% raster balance instead of flattening. |
Validation
- You can generate a warning if any overprinting or transparent objects are detected in the input PDF. The warning message will tell you whether transparencies have been flattened or not, as defined in the Flattening settings.
- You can generate a warning if single channel layers are detected in the input PDF. The warning message will tell you whether the single channel layers have been preserved or merged, according to the Preserve Single Channel Layers option.