|
|
|
| Color Management in Photoshop 5.x |
| Additional Color Controls |
There are some additional controls for color managing your Photoshop files:
Profile to Profile Conversion
Since the working space in Photoshop 5.x is device-independent, you can convert an image from one color space to another by selecting a source and destination profile. You might wish to do this for a few reasons:
| • |
|
If you ignored a Profile Mismatch when opening a file (or if the current color space was changed in the RGB, Grayscale, or CMYK Setup dialog boxes after the file was opened). |
|
| • |
|
If you scanned an image into Photoshop, in which case there would be no embedded profile, but the image data would be in the color space of the scanner. You would need to convert in order to bring the image into the working color space. |
|
| • |
|
If you wanted to print a proof in a different color space to an RGB color printer. |
To make a profile to profile conversion, choose Image > Mode > Profile to Profile:
This displays the Profile to Profile dialog box:
The dialog box options here are:
| • |
|
From: the current color space. If you want to convert from a different color space (for example, if you ignored the file's profile when opening it), you need to pick it from the list. Photoshop will not remember the originally embedded profile. |
|
| • |
|
To: the profile that describes the color space to which you wish to convert. |
|
| • |
|
Engine: The CMM that will perform the conversion using the profile parameters you have set. |
|
| • |
|
Intent: the render intent that you want the CMM to use. |
|
| • |
|
Black Point Compensation: Maps the darkest neutrals of the source color space to the darkest neutrals of the destination color space. Use this option when converting from RGB to CMYK, but not for RGB to RGB, or CMYK to CMYK conversions. |
Profile to profile conversion can cause problems if used incorrectly. The conversion changes the image data, but does not determine which profile will be embedded when the file is saved; that selection is made in the color settings (RGB, CMYK, or Grayscale Setup and Profile Setup). If you convert to a color space in the Profile to Profile dialog box that is not the working color space, the colors will not display accurately and any further conversions will be inaccurate.
When performing a profile to profile conversion, the From pop-up menu should be set to the original color space of the image and the To pop-up menu should be set to the desired mode. These settings cause Photoshop to use the current RGB, CMYK, Grayscale, or LAB settings.
For example, if you wish to convert a file with an embedded sRGB profile to Adobe RGB (1998), first make sure that your RGB color space is set to Adobe RGB (1998) in the RGB Setup dialog box. Then, in the Profile to Profile dialog box, choose sRGB from the From pop-up menu, and RGB from the To pop-up menu. Photoshop then converts the file to the current RGB working space:
| Note: The Profile to Profile dialog box does not default to the currently embedded profile in the From pop-up menu. You must set this yourself and, therefore, you must know beforehand what the embedded profile is. |
If you use Profile to Profile conversion to convert to a color space other than the working color space, you should not save the file with an embedded profile.
PostScript Color Management
Since PostScript supports the CIELAB color space, color management can also be
achieved at a PostScript printer rather than on the computer. Sending Lab files
or RGB files with embedded profiles to a printer that uses the same reference color
space as the host-based CMS represents the most device-independent workflow. You
can create files that can be printed remotely on unknown PostScript devices and
still achieve good results. There are two occasions when you can invoke PostScript color management: when saving a file as a Photoshop EPS and when printing.
Saving a file as an EPS
When you save a file as EPS, the EPS Options dialog box appears with a new option called PostScript Color
Management:
When this option is selected, Grayscale, RGB, and Lab files saved from Photoshop 5.x with embedded profiles can be read by PostScript Level 2 devices.
Printing to a PostScript printer
You will also see the PostScript Color Management option for PostScript printers
in Photoshop 5.x's Print dialog box:
When this option is selected, PostScript will perform the color conversion to the printer's color space.
There is also a selection you can make in the Space pop-up menu. The Space pop-up dialog specifies a color conversion done by Photoshop prior to sending the data to the printer. If you are using a PostScript driver you will see both CMYK and RGB device profiles listed here; if you are using a non-PostScript driver (i.e., device-specific) you will only see RGB device profiles.
PostScript color management and the Space pop-up menu are separate controls, though there may be times when you will want to use them together. For example, Level 2 PostScript printers can only convert RGB, LAB, and grayscale images. If you wanted to use PostScript color management for a CMYK image, you would need to choose RGB or LAB in the Space pop-up menu so Photoshop would convert the CMYK to RGB or LAB so PostScript could make its conversion.
The selections in the Space pop-up menu vary depending on the mode of the image you're printing:
| • |
|
Grayscale – only Gamma 1.8 or Gamma 2.2. |
|
| • |
|
RGB, Indexed Color, Lab – (that is, the RGB modes) all the default RGB color spaces as well as all the RGB and CMYK profiles (for both monitors and printers). |
|
| • |
|
CMYK – all the options for the RGB modes plus an option for Separations. |
If your printer's profile is not listed in the Space menu, you have four options:
| • |
|
Ask your printer's manufacturer for a profile that describes your printer. |
|
| • |
|
Use third-party profiling software to create a profile that describes your
printer. |
|
| • |
|
Create a profile for your printer using Photoshop's Built-in CMYK engine. |
|
| • |
|
Use sRGB for non-PostScript printers without profiles. Or, if you are getting
poor results from inkjet profiles, choose sRGB. This will produce "good
enough color" for most desktop color printers (especially in the Windows
environment). |
Printer Color Management
If you are printing to a non-PostScript printer, Photoshop will use the default Printer Color Management with RGB Color selected as the color space. This is because non-PostScript printer drivers can only accept RGB data. Keeping these defaults will usually achieve the best results when you print.
CMYK Preview
The CMYK Preview command enables you to preview what your RGB image will look like in CMYK mode, based upon your CMYK Setup configuration.
To preview and image in CMYK mode, choose View > Preview > CMYK:
In Photoshop 5.x you can also preview the Cyan, Magenta, Yellow, Black channels separately or as a composite CMY channel.
|
|
