How to manage color more efficiently in Photoshop
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Color management is a very complex concept, and many workers in the prepress field still have problems with the proper setting of options and operations in Photoshop software, which sometimes has serious consequences in printing. This article provides a brief description of some of the problems that are often encountered in prepress companies, with a view to inspiring and helping readers.
1 Profile setting and color management solution
If the image file does not have or is embedded with the wrong ICC profile (profile, Photoshop 5.X called profile, 6.X color profile, the same meaning), what should I do? It can be set in the “Profile Settings” menu in Photoshop 5.X: 1) If the image file is not embedded in the ICC profile, you can specify a hypothetical profile and then automatically convert it; 2) If the image's profile is current If the color settings do not match, you can select the three options "Ignore", "Convert" and "Ask when open".
Whether to embed the ICC property file when saving the image file is also set in this menu in Photoshop 5.X; in Pho-toshop 6.X, the option to embed the property file appears every time you save the image file.
Depending on the purpose of the image output, Photoshop 6. The "Off", "Keep embedded configuration file", and "Convert" options in the X color management scheme have completely different effects. Let's talk about the places to be aware of when setting these three options.
Option: Off
Images without embedded feature files will be processed within the currently defined working color space, and there are no assumed property files; if the image embedded feature file is inconsistent with the current color settings, the original image's properties file will be Was deleted, this option is equivalent to eliminating the color management function.
Option: Keep embedded configuration files
This option is new in Photoshop 6.0. The processing of images without embedded feature files is completely the same as the option: "Off"; if the image embedded feature file is inconsistent with the current color settings, the image is still displayed on the display according to the color described in the embedded profile, the current The color setting has no effect on this image. (Note: This option should be used with caution, as it is possible that the image is displayed very well on the display, but the color is greatly skewed during printing.)
Option: Convert
If the property file embedded in the image does not match the current color settings, the property file is converted to the current color settings. For images without embedded feature files in Photoshop 5. An assumed property file can be specified in X; in Photoshop 6. X has no such option.
2 conversion of feature files
Image properties files can be converted using the "View to Profile" (Photoshop 5.X) or "Convert to Profile" (Photoshop 6.X) submenu when opening images in Photoshop. This menu can be used when you want to apply a scanned color separation profile to an image or convert a CMYK image (for offset printing) to another form of CMYK image (for gravure printing).
Note: Photoshop 5. X saves the image when the current working color space is embedded as a feature file. Generally, only RGB, CMYK or Lab can be selected as the target color space. If other feature files are selected for conversion, such as: different from the current working color space. But when saving images, Photoshop 5. X can only embed the current working color space as a feature file into the image, so it may embed the wrong property file! And in Photoshop 6. This problem in X no longer exists, and the image after the conversion of the feature file is automatically saved in the save file.
3 Color management in practice
There are many options for color management in Photoshop. Below I will list some of the situations that often occur in production and solutions for reference.
1) RGB scanned image with profile
Most of the high-end scanner software currently used in prepress companies can customize the output profile, which lays the foundation for users to create an ideal color management mode. For example, Heidelberg scanning software NewColor can be directly in the "Profilmanager" sub- The RGB output profile is defined in the menu. Just set the output profile in the scanning software to match the "RGB Settings" menu in Photoshop, so that the image is approximately the same as the screen display in NewColor in Photoshop, which is an ideal color management in production.
Note: The ICC profile must be stored in the “Windows→System→Color” folder on the PC; in the “System Folder→ColorSync Profile” folder on the MAC, so that it can be set in different software colors. The corresponding ICC profile is called from the drop-down menu.
2) RGB scanned image file without feature file
Many inexpensive scanners do not support scanning profile files and do not provide IT8 standard manuscripts for scan correction. But you can also create scan profiles for these scanners, because the profile creation software is completely independent of the input device! By scanning a color IT8 standard original, you can create a scanner's profile. The scanners that come with these scanners usually do not support feature files, in which case you must use the features in Photoshop.
Open the image in Photoshop using the "Overview to Profile" (Photoshop 5.X) or "Convert to Profile" (Photoshop 6.X) in the "Mode" menu (Figure 2).
Note: After making the scan profile, you can no longer change the settings in the scanner and scan software (such as brightness, contrast, etc.), or use the automatic function of the scan software, because this conflicts with the feature file! If you need to change the relevant settings, you must also reproduce the profile that reflects the actual condition of the scanner.
3) RGB image file with "error" property file
What should I do when I open an RGB image with a feature file embedded and the embedded feature file is not the same color as the one currently set in Photoshop?
If you select “Do not convert”, the image data will remain unchanged, but the color of the image on the display may change significantly; if “Convert” is selected, the image data changes, but the color of the image display may not be much different. . Normally choosing "convert" will give better results, so it is recommended to "automatically convert" or "question when opening".
You can do it in Photoshop6. X uses "Keep the built-in profile" so that the image is still displayed in the built-in properties file, which is a convenient way for RGB images that are ultimately converted to CMYK mode. Do not use this menu if the RGB image is still in RGB mode.
Note: Since the image-embedded ICC profile is inconsistent with the settings in Photoshop, the feature file mismatch dialog box will appear when the image is opened in Photoshop. Normally, the conversion is selected.
4) RGB image files without feature files
If an RGB image file is not embedded in the property file, in general, you can select a property file most commonly used by the operator in the "From" drop-down menu in the prompt box of the open file, and select the corresponding one in the "To" menu. CMYK or RGB mode.
5) CMYK scan data with profile files
If you get a batch of scanned images, and the scanner operator tells you the color separation settings during scanning, or provides you with the corresponding ICC profile, you can do it in "CMYK Settings" or "CMYK Working Color Space". Make settings.
Note: You can select or set a profile that is consistent with the scanner in the CMYK setup menu for a better screen display.
From this point, we can extend it a bit. We can scan the image into RGB mode when the scanner scans. With ICC profile, we can use the same color separation on each computer, whether it is PC or MAC. Settings, because sometimes image correction with RGB images has advantages over CMYK, such as the use of all filters. RGB images are converted to CMYK images before final output; the same unfamiliar RGB images can be separated using common color separation properties files. Many are avoided due to the uncertainty created by using Photoshop's Color Settings menu!
6) CMYK scanned images without feature files
If you get CMYK scanned images without feature files, no matter how good the quality of these images, you should continue to work in Photoshop. This is a common occurrence in prepress companies because these images are already in CMYK mode. Try using the Cancel Color Management feature, which means "Do not embed an overview" in Photoshop 5.X, which is available in Photoshop 6.X for storage.
The purpose of this setting is to protect the color of the image. If you do not cancel the color management function in Photoshop and select the wrong Phot-oshop profile, it will lead to wrong color conversion!
7) CMYK images with "error" profile
In principle, as with the RGB images mentioned above, the conversion is usually selected. The color loss caused by the conversion between CMYK and CMYK is not as serious as the conversion between RGB and RGB.
One thing to note here is that the profile of different CMYK images (including grayscale images) determines the number of different black plates, for example: when grayscale images are converted to CMYK images, different color separation methods (characteristic files) are used. Produce a different number of black versions; for example, a CMYK image uses a higher number of GCR color separation methods. If you choose to convert directly if there is a color mismatch, all of this information will be lost! For the above mentioned situation, it is best to select "Ask when opening". This way you can see which feature file is embedded in the CMYK image when you open the image. You can also choose "Do not convert" to open the image to see if the image meets the needs of the output, and if possible, manually correct it.
There is a new feature in Photoshop 6.X that "Keep embedded overview". If you select this image that does not match the feature file, the display will be displayed according to the feature file embedded in the image, such as with a file suitable for gravure printing. The image pre-views the actual effect of gravure printing on the display; images with a suitable document for the newsprint printing feature preview the actual effect of newsprint printing on the display.
8) CMYK image files without feature files
For a CMYK image without a property file, you can specify a hypothetical property file. For image files that were saved a long time ago (such as Photoshop 4.0 does not support property files), you must specify a hypothetical property file and then convert it.
4 Summary
Applying the color management options in Photoshop makes it easy to achieve the following main goals:
· Improve the quality of the image;
· The display of the display in a working group is definitely inconsistent. Using the RGB profile can make the image reach near possible consistency on different displays!
· The same CMYK images in a working group are definitely inconsistent on different displays. These problems can also be solved with the help of device-independent ICC profiles!
· Images can be exchanged between PC and Mac with minimal color loss;
· An image can be converted by different ICC profiles so that the same image can be applied to different output processes;
• A cheaper printer can be used as a digital proofing device. Although color management has different RIP solutions, the price is relatively expensive, and some color management functions in Photoshop and other software can be used to obtain proofs that can preview the final prints using inexpensive inkjet printing. An expensive color management workflow can't be said to be a serious challenge.