The final part of the series on image color profiles covers the practical aspects of this topic. Readers will know where and how to select and customize color profileand also how to convert an image from one color space to another.
So let's get down to practice. Let's consider algorithms for choosing a color space for a camera and various graphic editors.
In the camera settings the choice of the JPEG color space (also affects the built-in RAW preview) occurs in the menu:
In Adobe Lightroom the choice of color space occurs in:
At Adobe Camera raw (ACR) the choice of color space occurs in the menu that opens by clicking on the "link" under the main preview of the image:
In Capture One the choice of the color space of the exported file occurs in the settings of the "processing recipe" (Process Recipe):
Nikon Capture NX-D color space settings are found in the Tool → Preferences menu:
Canon Digital Photo Professional (DPP) the choice of working color space is in the settings menu:
And also in the Tool Palette:
It is worth noting that DPP lacks the ability to work in ProPhoto RGB, however, instead of it there is a choice of very large space Wide Gamut RGB.
To Adobe Photoshop processed images in the color space in which they arrive without forced conversion to the working color space, you must select Preserve Embedded Profiles in the color management policy settings (Edit → Color Setting → Color Management Policies):
In the case of processing an image in a color space other than the one in which it will be further used, it must be converted (converted) into the final color space.
If the image is used on the Internet or if it is not known how it will be used in the future, it must be converted to sRGB space.
... In this case, when working in 16-bit mode, it is recommended to first perform the conversion procedure, and only then transfer the image to 8-bit mode.
To convert an image from one color space to another in Adobe Photoshop, use the command Edit → Convert to Profile (Editing → Convert to Profile).
As an algorithm for recalculating colors (Intent), it is necessary (except in very specific cases) to choose Perceptual (for the maximum possible preservation of the visual ratio between the most and least saturated colors) or Relative Colorimetric (in order to preserve colors that fit into the final color space, without any visual change and discard colors outside the final color space).
Perceptual mode compresses / compresses colors in order to avoid posterization of "out-of-grip" colors and, if possible, preserve the visual relationship between highly saturated and low-saturated colors.
Relative Colorimetric mode converts an image to a different color space without visually altering the colors in the target color space and cuts off “out-of-gamut” colors.
The choice between the Perceptual and Relative Colorimetric options is usually made by the user visually, according to the preview. It should be noted that if the difference between the results is strongly visible, then in some area of \u200b\u200bthe image the colors go beyond the finite color space. In this case, when the Relative Colorimetric option is selected, the image will be posterized in this area).
If the area of \u200b\u200bthe image with "out-of-range" colors is small, you can 1) correct it locally (reduce the saturation in this area), or agree to posterization of the image in this area and choose Relative Colorimetric to obtain the most visually pleasing image as a whole, 2) select Perceptual, to exclude posterization as much as possible (however, the overall saturation of the image will decrease).
Working with color right: Photoshop's color profile 21.12.2014 20:08
Photoshop's Color Profile is a color management system that determines the ratio of colors in an illustration for printing.
To make it clear, a simple example: black in print can be represented differently all 4 colors at 100% or black 100% the rest 80%, or all at 80% or only Black 100% , the rest are zeros- when printing, it will still give us black on paper. True, under certain conditions, the difference between them will be visible on the print.
In order not to delve into terminological and professional jungle, consider specific example what it consists of and, most importantly, how it can be configured.
First of all, you need to remember that printing on gloss is different from printing on plain paper, and even more so on newsprint. Here, dot gain is different and the total ink coverage affects, the printing machines are different ..
As for the profile for printing on gloss, everything is simple, find out in the printing house which profile is used (usually it is one of the standard ones, for example Fogra27) and set it up when processing photos for gloss. Attention! Be sure to check with the print shop which profile they are using. And here is a profile for newspaper printing, let's take a closer look
First of all, I want to note. that what I cite in the example is tested in our printing house and is not the ultimate truth. Moreover, I admit that similar settings not suitable for the print shop where you print. But, having understood the principle of setting the profile, you can adjust it to the conditions of any printing house.
So press SHIFT + CTRL + K in Photoshop ... and go to the color profile settings.
In the section "workspace" we are interested in the lineCMYK. Actually, there is already a standard profile for newspaper printing ( has in the titleNewspaper or newsprint), but there is an opinion that today the principle of standardization is somewhat outdated, therefore we choose "CustomCMYK "...
And we begin to set up
Dot gain is standard and for a newspaper (from 25 to 35%) we set average - 30%
Black ink no more than - 100% (if you set less, then black ink will be printed in gray)
Total coverage is an important parameter for newspaper printing. Maximum amount ink to be used for printing. For example, if we leave 400%, then 100% of all 4 colors will be used to print black, and if 300%, then 75. As a result, everything will spread like a blot on loose newsprint, plus the ink will dry for a long time. Therefore, for newspaper printing, the total coverage is in the range from 240 to 270%. Which one exactly is your choice (or your printing house), personally I have it - 260.
Set aside the "color management strategy" and keep the color settings. We press save and here it is important to specify the correct location for saving, so that later you can easily select the one we need from the list of profiles. If necessary, write a comment (for example, setup details), you're done. Now in the line "settings" we can immediately select a ready-made profile.
Attention. Track where your Photoshop is saving color profiles! After correct saving, its name should be displayed in top line color settings windows ...
Now let's get back to the "management strategy" and here we need to decide whether we want the photo to be automatically transferred to our profile or not. Since we changedCWYK colors, then upon openingCMYK photographs we can already receive the decomposition of colors in accordance with our profile. To do this, select "convert to workspaceCMYK ", and with the checkboxes below, select whether Photoshop will warn us or will do everything by itself.
To secure the material, try to make a profile in the same way, where the black will be best (maximum) , and the total coverage will be 270%. Name itBlack and also - save.
This color profile will come in handy.
If you don't change the default settings, Photoshop will export your files so that the colors change when viewed in a browser. This is due to the default working space in Photoshop set to the Adobe RGB profile. While this profile is ideal for printing photographs, using it for web design can lead to incorrect display design. For this reason, you need to change the workspace when working on web projects. There are two main opinions about the best workspace to use for web projects. Some argue that the workspace should match the designer's monitor profile, while others suggest using sRGB. With both methods, you can actually achieve equally good results, but in different ways.
The advantage of using a monitor profile as a workspace is simplicity. There is no need for any transformations or adjustments. However, when exporting images, the "Convert to sRGB" option must be disabled in the "Save for Web and Devices" dialog box. Otherwise, a color change will occur when saving. This method is extremely simple and works well if the designer is working alone on the project. However, in essence, in this case, you bind the document display to your monitor profile. If you open the PSD file on a different computer, the color values \u200b\u200bmay not change, but they will look different than on your monitor.
To maintain a high degree of color matching both after export and during editing, I recommend using sRGB for all workspaces. The sRGB profile provides a baseline for accurate color reproduction across all computers. However, when you set your workspace to sRGB, the document display will not match what the browser ultimately displays (unless you embed the ICC profile in the image file and the browser can interpret it correctly). This can be easily corrected by working with Proof Color. On the menu View → Proof Setup change the setting to "Monitor RGB". Then check that the option is installed View → Proof Colors... You should see changes in open document... The image should match the browser display. It may be difficult to keep the option enabled Proof Colorsbut make it a habit.
Using sRGB workspace - the best solution to match the edited image with its exported copy in Photoshop. Therefore, be sure to enable the option Proof Colors and configured the monitor profile. When you save an image using the "Save for Web and Devices" method, it doesn't matter if the "Convert to sRGB" option is enabled, but it is important that the "Embed Color Profile" option is disabled. To change the workspace, open the Color Settings dialog ( Edit → Color Settings). You can change the RGB workspace to sRGB IEC61966-2.1. You can also see a number of other settings in this dialog box.
Accurate and reliable color management requires accurate ICC-compliant profiles for all color reproduction devices. For example, without an accurate scanner profile, a well-scanned image may not display correctly in another program due to differences between the display algorithms used by the scanner and the program. Inaccurate colors can lead to good picture unnecessary and possibly harmful "improvements". With an accurate profile, the software importing the image can correct the difference with the device and reproduce the true colors of the scanned image.
The color management system uses the following types of profiles.
Monitor profiles: Describe the current color reproduction method of the monitor. This profile should be created first because accurate color reproduction on the monitor screen allows important color decisions to be made during the design phase. If the colors on the monitor screen do not correspond to the actual colors of the document, then it will not be possible to maintain the accuracy of color reproduction during operation.
Input Device Profiles: Describes the colors that the input device can capture or scan. If with digital camera Since several profiles are supplied, Adobe recommends choosing Adobe RGB. Otherwise, you can use the sRGB profile (which is the default for most cameras). In addition, experienced users can apply different profiles for different light sources. When working with a scanner, some photographers create separate profiles for each type or brand of film being scanned.
Output device profiles: describe the color space of output devices such as desktop printers or printing presses. The color management system uses output device profiles to correctly map document colors to colors within the gamut of the output device color space. In addition, specific printing conditions such as paper and ink types must be considered in the output profile. For example, glossy and matte paper can represent different color ranges. Color profiles are included with most printer drivers. Before investing money in creating custom profiles, it makes sense to try out the standard ones.
Document Profiles: Describes the specific RGB or CMYK color space used in the document. By assigning a profile, or tagging a document with a profile, the application determines the actual colors of the document. For example, writing R \u003d 127, G \u003d 12, B \u003d 107 is just a set of numbers that different devices will display differently. However, when tagged with the Adobe RGB color space, these numbers define the actual color or wavelength of light (in this case, one of the shades of purple). If color management is enabled, then adobe applications automatically assign a profile to new documents based on the workspace settings specified in the Color Settings dialog box. Documents without profiles assigned are called unmarked and contain only the original color values. When working with unlabeled documents, Adobe applications use the current working environment profile to display and edit colors.
Color management with profiles
A. Profiles describe the color spaces of an input device and document B. Based on the descriptions in the profiles, the color management system identifies the actual colors of the document C. Based on data from the monitor profile, the color management system translates the numerical values \u200b\u200bof the colors in the document into the monitor color space D. Based on information from the output device profile, the color management system converts the numerical values \u200b\u200bof the colors in the document to the color values \u200b\u200bof the output device to ensure correct colors when printed.
Monitor Calibration and Sizing Information
With the profiling software, you can calibrate your monitor and determine its characteristics. Calibrating your monitor allows you to adjust it to a specific standard, such as setting your monitor to display colors with a standard color temperature of 5000 ° K (Kelvin) white point. Monitor characterization simply creates a profile that describes the current color reproduction.
The monitor calibration procedure includes setting the following video parameters:
Brightness and contrast: the overall level and intensity range of the monitor, respectively. These parameters are no different from similar television parameters. Monitor calibration software allows you to set the optimal brightness and contrast range for calibration.
Gamma: the brightness of the halftones. The monitor reproduces values \u200b\u200bfrom black to white in a non-linear way - the value graph will be a curve, not a straight line. Gamma defines the position of the point that lies in the center of the curve between black and white.
Phosphors: substances that emit light in cathode ray tube monitors. Different phosphors have different color characteristics.
White point: The color and intensity of the maximum whiteness that the monitor can reproduce.
Calibrating and adjusting the monitor profile
Calibrating a monitor means adjusting it to a known specification. After calibrating the monitor, the program allows you to save the resulting color profile. A profile determines the color behavior of a monitor - what colors a given monitor can or cannot reproduce, and how numerical color values \u200b\u200bshould be converted to accurately display them.
Note. Monitor performance changes and degrades over time, so you should calibrate and profile your monitor once a month. If it is difficult or impossible to calibrate your monitor to a standard, it may be too old and discolored.
Most profiling software will automatically assign new profile monitor as the default profile. For the procedure for manually assigning a monitor profile, see the Help for your operating system.
- Make sure the monitor is on for at least half an hour. This time is enough for the monitor to warm up and provide the most stable color reproduction.
- The monitor must be capable of displaying thousands of colors or more. It is best if the monitor displays several million colors, that is, it operates at 24-bit or greater color depth.
- The desktop should not have a colored patterned background - only neutral shades of gray. Variegated patterns or bright colors around a document interfere with accurate color perception.
- To calibrate and profile your monitor, do one of the following:
- For Windows, install and run utility program monitor calibration.
- For Mac OS, use the Calibration tool located under the System Preferences / Monitors / Color tab.
- For best results use third party programs and measuring devices. Typically, a combination of a colorimeter and specialized software allows you to create more accurate profiles, since the instrument evaluates the colors displayed on the monitor much more accurately than the human eye.
Setting a color profile
Color profiles are often set when a device is added to the system. The accuracy of these profiles (often called standard profiles or nested profiles) is different for different equipment manufacturers. You can also obtain device profiles from your service provider, download them from the Internet, or create custom profiles using professional equipment.
- On Windows, right-click the profile and select Install Profile. Alternatively, copy the profiles to the WINDOWS \\ system32 \\ spool \\ drivers \\ color folder.
- On Mac OS, copy the profiles to / Libraries / ColorSync / Profiles or / Users / [username] / Libraries / ColorSync / Profiles.
After installing color profiles, restart your Adobe applications.
Embedding a color profile
To embed a color profile in a document created in Illustrator, InDesign, or Photoshop, the document must be saved or exported in a format that supports ICC profiles.
- Save or export this document in one of the following formats: Adobe PDF, PSD (Photoshop), AI (Illustrator), INDD (InDesign), JPEG, Photoshop EPS, Large Document Format, or TIFF.
- Select the option to embed ICC profiles. The exact name and location of this setting varies by application. See Adobe Help for more instructions.
Embed a color profile (Acrobat)
A color profile can be embedded in an object or the entire PDF. Acrobat attaches the appropriate profile specified in the Convert Colors dialog box to the selected color space in the PDF. additional information see the topics about converting colors in Acrobat Help.
Change the color profile of a document
It is extremely rare to change the color profile of a document. This is because the application automatically assigns a color profile to the document based on the settings in the Color Adjustments dialog box. You should only change the color profile manually when preparing a document for output on another device or when changing the strategy for working with a document. Only advanced users are recommended to change the profile.
You can change the color profile in your document in one of the following ways.
- Assign a new profile. This does not change the color values \u200b\u200bin the document, but the new profile can significantly change the appearance of the colors displayed on the monitor screen.
- Remove the profile so the document no longer uses color management.
- (Acrobat, Photoshop, and InDesign) Convert colors in the document to the color space of another profile. The color values \u200b\u200bare shifted so as to preserve the original appearance of the colors.
Assign or remove a color profile (Illustrator, Photoshop)
Choose Edit\u003e Assign Profile.
Select an option and click OK.
Cancel color management in a document: removes the existing profile from the document. Select this option only if you know for sure that you do not need color management in your document. After the profile is removed from the document, the color rendering will be determined by the application workspace profiles.
Working [color model: working space]
Profile
Assign and remove a color profile (InDesign)
- Choose Edit\u003e Assign Profiles.
- If you are using an RGB or CMYK profile, select one of the following options:
Undo (Use Current Workspace): removes the existing profile from the document. Select this option only if you know for sure that you do not need color management in your document. After you remove a profile from a document, the color rendition will be determined by the application desktop profiles and you can no longer embed profiles in the document.
Assign current workspace [workspace] assigns a workspace profile to a document.
Assign profile: allows you to select a different profile. The application assigns a new profile to the document without converting the colors to profile space. In this case, the color rendition on the monitor screen can change dramatically.
- Choose a rendering method for each type of graphics in your document. For each type of graphic, you can choose from four standard methods, or select the Use Color Adjustment Method option (in this case, the rendering method specified in the Color Adjustments dialog box is used). For more information on rendering methods, see Help.
The following are the types of graphics.
Pure color method: defines the render method for the whole vector graphics (solid areas of color) in native InDesign objects.
Default Image Method: defines the default rendering method bitmapsplaced in InDesign. It can be changed for individual images.
Post-application method- Specifies the rendering intent for the proof space or target image for colors that result from transparency blending on the page. Select this option if your document contains transparent objects.
- To view the results of assigning a new profile in the document, select View and click OK.
Recalculate document color values \u200b\u200bfor another profile (Photoshop)
- Choose Edit\u003e Convert To Profile.
- In the Target Space section, select a color profile to convert colors in your document to. The document will be converted and marked up with a new profile.
- In the Conversion Options section, specify the color management algorithm, rendering method, and black point and dither options (if available). (See the "Color Conversion Options" section.)
- To flatten all layers in your document during conversion, select Flatten Down.
Convert document colors to Multichannel, Device Link, or Abstract profiles (Photoshop)
- Choose Edit\u003e Convert To Profile.
- Click the Advanced button. The following additional ICC profile types are available in the Target Space section:
Multichannel: profiles supporting more than four color channels... Useful when printing with more than four colors.
Device communication: Profiles that convert from one device color space to another without using an intermediate color space. Useful when specific device value mappings are required (for example, 100% black).
Abstract: Profiles that let you apply custom effects to pictures. Abstract profiles can have both input and output LAB / XYZ values, allowing you to create custom LUTs for special effects.
Note. Grayscale, RGB, LAB, and CMYK color profiles are grouped by category in Advanced View. They are combined in the "Profile" menu in the basic view.
- Select Preview to preview the color conversion results in your document.
Convert document colors to another profile (Acrobat)
IN pDF documents colors are converted when you choose Tools\u003e Print Production\u003e Color Conversion. For more information, see the topics about converting colors in Acrobat Help.
When working with digital images, sooner or later we are faced with issues related to color reproduction. The most common of them are: "Why does the same picture look different on different monitors?", "Why do I see different colors when printing, not the same as on the monitor?" not like in photoshop? "...
All these questions are relevant to the topic of our article. Let's try to figure them out.
Each display device can reproduce a specific set of colors (this is called the gamut of the device, in English gamut). The color gamut of different devices may vary markedly, and colors outside the general gamut will not appear the same on the two devices. For example, a monitor can display some colors that are not available to a printer, and vice versa. As a rule, monitors are better at displaying bright bright colors (this is due to the fact that the image on them is backlit!). Moreover, in different models devices of the same type (for example, monitors), the color gamut can also vary greatly.
Medium color gamut inkjet printer... The picture is rather arbitrary, because the same printer will have different coverage depending on the ink and paper used.
** Standard color spaces
In order to bring certainty to the work with color, abstract color spaces were "invented" - not tied to specific devices... There are three most famous and widespread abstract spaces: * sRGB. This is a rather tight space, so almost any monitor can display all of its colors. The sRGB color space is the de facto standard for the Internet (and for printing images in many darkroom environments); * Adobe RGB (1998). This space is much wider, therefore, there is less color distortion during work. It is well suited for preparing images for printing. However, it should be borne in mind that not every monitor is capable of displaying all the colors of this space. * ProPhoto RGB. Its color gamut is so great that it includes colors that are not perceived by the human eye and do not even exist in nature at all!
Comparison of color gamuts of abstract color spaces.
Color field - area of \u200b\u200bvisible colors
A reasonable question arises - what kind of space to choose for work?
** Preparing images for publication on the Internet
If you plan to upload processed images to the Internet or print them in a darkroom, be sure to (!) Convert them to sRGB space. The fact is that many browsers believe that all images should be in sRGB, and if the picture is in a different profile, the color will be noticeably distorted.
If you are working in Photoshop, this is done by the menu command Editing\u003e Convert to Profile... From the variety of options on the list Target Space have to choose sRGB (see fig.).
Another option is to save images with the command File\u003e Save for Web, in this case, in the save dialog (on the left), check the box Convert to sRGB (Convert to sRGB).
If you are using Lightroom, then in the export dialog you should also set sRGB - this setting is done in the section File Settings.
If you use another editor, you need to set the settings there in the same way.
** When is wider space needed?
If you are using a monitor with a wide color gamut, printing your photographs on high quality photo printers or Durst cameras, it makes sense to save your work in the wider Adobe RGB space. But keep in mind that visually, the difference will not be visible in all plots (in comparison with sRGB).
** In summary, if you have no good reason to use other color spaces, it makes sense to work in sRGB.
