About color conversion
Colors must often be converted when they are displayed on a monitor or sent to a printer. Conversion is necessary when the color models do not match (for example, when CMYK color is displayed on an RGB monitor, or when a document with images in an RGB color space is sent to a printer).
Acrobat uses the source color spaces of objects in a PDF to determine what (if any) color conversion is required, for example, from RGB to CMYK. For images and objects that contain embedded color profiles, Acrobat uses the information in the profile to manage the appearance of the color. For files that comply with the PDF/X family of standards, the OutputIntent is used to manage the colors in the file. Unmanaged colors, however, do not use profiles, so a profile must be temporarily used for conversion. The Color Management panel of the Preferences dialog box provides profiles for converting unmanaged colors. You can also select specific profiles based on local press conditions.
If you output your PDF to a high-end device or incorporate it in a prepress workflow, you can convert color objects to CMYK or another color space. Unlike other Acrobat features that temporarily convert colors during printing or viewing, the Convert Colors feature changes the color values in the document. In the Convert Colors dialog box, you can convert the colors of a single page or an entire document.
The Convert Colors dialog box converts all colors in the document or all colors for specified object types to the destination color space. To convert only the colors of a selected object, use the Edit Object tool.
A. Conversion Attributes B. Document Colors
Depending on the color spaces you select, color conversion preserves, converts, or maps (aliases) color values from the source color space to the destination space as follows:
- Objects with untagged (Device) data are converted to the destination space using the working space profiles as the source. This conversion is applied to all untagged spaces, RGB, CMYK and grayscale, whether stand-alone or as alternate value for spot colors.
- Objects in device-independent color spaces (CalGray, CalRGB, or Lab) can be preserved or converted. If converted, Acrobat uses the device-independent object information.
- Objects set in spot colors can be preserved, converted, or mapped (aliased) to any other ink present in the document. Objects include Separation, DeviceN, and NChannel color spaces. Spot colors can also be mapped to a CMYK process color, if the process color model of the destination space is CMYK. Spot colors mapped to other inks can be previewed in the Output Preview dialog box.
If you want to convert specific spot plates, use Ink Manager in combination with the Convert Colors tool. To convert only specific spot plates to process, map them to process in Ink Manager. Otherwise, all spots in the document are converted to process if you have selected Spot Color as the color type.
Select Embed to embed the profile. Selecting Embed tags all objects with the selected conversion profile. As an example, a document can contain five objects: one in grayscale and two each in the RGB and CMYK color spaces. In this case, you can embed a separate color profile to calibrate the color for each color space, for a total of three profiles. This process is useful if your RIP performs color management of PDFs or if you are sharing PDFs with other users.
Select Convert Colors To Output Intent and specify the output intent profile to be used instead of the document’s current output intent. An output intent describes the color reproduction characteristics of a possible output device or production environment in which the document is printed. This choice is not available if the document does not have an output intent. (PDFs that don’t comply with standards, such as PDF/X or PDf/A, often lack an output intent.)
If certain objects in the PDF don’t match the color space of the document, you can use the Edit Object tool to correct them. The Edit Object tool can change the color space of selected objects. For example, if you place an RGB image in a CMYK document, use this tool to change only the RGB image and not affect the other PDF colors. You can embed the profile with the object.
The Edit Object tool doesn’t let you change the output intent, because that affects the entire document.
You can remove the embedded color profiles from images and other objects in the PDF. Without the embedded profile, Acrobat uses the working space profile of the object to determine how to handle the appearance of the color.
The Ink Manager provides control over inks at output time. Changes you make using the Ink Manager affect the output, not how the colors are defined in the document.
Ink Manager options are especially useful for print service providers. For example, if a process job includes a spot color, a service provider can open the document and change the spot color to the equivalent CMYK process color. If a document contains two similar spot colors when only one is required, or if the same spot color has two different names, a service provider can map the two to a single alias.
In a trapping workflow, the Ink Manager lets you set the ink density for controlling when trapping takes place, and it lets you set the correct number and sequence of inks.
InDesign and Acrobat share the same Ink Manager technology. However, only InDesign has the Use Standard Lab Values For Spots option.
A. Process ink B. Aliased Spot ink C. Spot ink
- Choose Tools > Print Production > Ink Manager.
- Choose File > Print, and click Advanced. In the Output panel of the Advanced Print Setup dialog box, click Ink Manager.
- Choose File > Save As Other > More Options > Encapsulated PostScript or PostScript. Click Settings, and then click Ink Manager.
Using the Ink Manager, you can convert spot colors to process colors. When spot colors are converted to process color equivalents, they are printed as separations rather than on a single plate. Converting a spot color is useful if you’ve accidentally added a spot color to a process color document, or if the document contains more spot colors than are practical to print.
- To separate individual spot colors, click the ink-type icon to the left of the spot color or alias ed spot color. A process color icon appears. To change the color back to spot, click the icon again.
- To separate all spot colors, select Convert All Spots To Process. The icons to the left of the spot colors change to process color icons. To restore the spot colors, deselect Convert All Spots To Process.
Selecting Convert All Spots To Process removes any ink aliases you’ve set up in the Ink Manager and can also affect overprinting and trapping settings in the document.
You can map a spot color to a different spot or process color by creating an alias. An alias is useful if a document contains two similar spot colors when only one is required, or if it contains too many spot colors. You can see the effects of ink aliasing in the printed output, and you see the effects onscreen if Overprint Preview mode is on.