What are color profiles? -Color profiles: theories-

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In “Creating CMYK data -Using color profiles-” we covered how to create CMYK data. During the lesson, the term “Color profile” was mentioned several times.

In this lesson, we will go deeper into the subject of “color profiles”, and how to use them.

https://tips.clip-studio.com/en-us/articles/553


[1] Color profiles: purposes and roles

(1) Colors change depending on monitors


The goal of color profiles are to avoid color changes when working on images in different environments.

They are especially useful when trading data between environments, or when creating color images with multiple people.


Generally, in RGB format, colors are divided into the 3 basic colors R (red), G (green), and B (blue), with each color divided into 256 levels, ranging from 0 (black) to 255 (red, blue, or green). Colors are expressed by mixing these 3 colors. For example, “R: 255, G: 0, B: 0” would represent red.


However, when this data “R:255, G: 0, B: 0” is displayed on a monitor, the actual “red” that is displayed changes from monitor to monitor.

In reality, the data “R: 255, G: 0, B: 0” is “the reddest color that can be displayed on that specific monitor”. Since each monitor’s color gamut differs from model to model, the displayed colors of “R: 255, G: 0, B: 0” also vary from monitor to monitor.


Similarly, the actual printed color of CMYK color data will change based on the printer model, ink, paper materials, and so on.

The same can be said about devices, such as digital cameras, printers and scanners that can display, store or output images.

As such, RGB and CMYK can be called relative color data, whereas the displayed color is dependent on the displaying device.


With this in mind, what is necessary for the created image to be printed, or be displayed on other monitors with the same colors as the created environment?



(2) Recreating consistent colors using color profiles


“Color profiles” are used to minimize differences between devices in order to import, display and print with consistent colors.

Color profiles themselves are data of a device’s color characteristics (how it handles color).

The data contains information on how RGB or CMYK data is actually displayed and printed, based on a color space that is not dependent on devices (called a Lab color space).


By embedding a color profile in the image data, the monitor that was used when creating the image can know “the actual display color”.

Based on this “actual display color”, devices that output images such as monitors, home printers, and commercial printers convert the file to RBG and CMYK, while matching the color profile installed in the output device, and output the file accordingly.

This color data processing method makes it possible to display and print with minimum difference from the initial colors.


There are currently various color profiles, some created for each device by manufacturers (sometimes installed with the driver of the device or distributed on the manufacturer's homepage etc.), while others are more versatile, and created assuming a standardized environment (sRGB, Adobe RGB, Japan Color 2001, etc.).

You can also create your own profile based on your monitor environment and printer.

For more information, refer to [5] Common color profiles.


[POINT]

Even if a color profile is embedded, intended colors cannot be displayed if the used application does not support the profile.

On Windows, environments up to Windows XP do not consider color profiles and will display an image’s RGB data based on the monitor’s color characteristics.

Environments after Windows Vista will display images as having embedded sRGB profiles. As this may differ depending on the manufacturer, please check your product’s manual for details.

In a macOS environment, colors will be displayed as intended even on applications without profile support, as the OS itself supports color profiles.


[2] Using color profiles

Here, we will explain how to use RGB color profiles.



(1) Embedding color profiles


The basic operation is the same as for CMYK. From the [File] menu choose → [Export (Single Layer)] → [.jpg (JPEG)], [.tif (TIFF)], [.psb (PhotoshopBig Document)] or [.psd (Photoshop Document)] to display the [Export Settings] dialog box. Set [Expression color] of the dialog box to [RGB color] and check [Embed ICC profile] to save.


When saving, the RGB profile specified in the [Preview of color profile] dialog box under the [View] menu →[Color profile]→[Preview settings] will be embedded.

If not specified, the profile set in the [File] menu ([CLIP STUDIO PAINT] menu on macOS) → [Preferences] dialog → [Color conversion] → [RGB profile] will be embedded.


The use of the preview is also basically the same as that of CMYK.

Select RGB profile from [Profile for preview] in the [Preview of color profile] dialog box.


Note that the [Profile for preview] will select the color profile specified by the OS by default. If the OS is unable to specify the RGB profile, the “Preferences” default RGB profile will be selected.

Additionally, tonal corrections cannot be applied when selecting an RGB profile.



(2) Things to consider when using RGB profiles


If CMYK profiles are used when printing at a print shop, under what circumstances are RGB profiles necessary?

This section will explain when RGB profiles can be useful, and explains how to use color profiles correctly.


<When using multiple applications>

When editing images across multiple applications, the profile does not have to be changed, as the monitor, as well as the colors, are the same.


When unintended colors are displayed without an embedded profile, the application opening the file may be displaying the image with a different profile than the monitor. Check the color profile settings of the display application.


<When printing at home>

Common household inkjet printers convert RGB data to CMYK (more colors in some models) data and print with ink.


As CLIP STUDIO PAINT hands the data to the OS without embedding a color profile when printing regardless of the profile, print results will rely on the printer profile that converts RGB data to CMYK data. Due to this, there is no need to embed a color profile.

The printer’s RGB profile can be specified as “Profile for preview”, but the print results may differ greatly depending on the profile’s characteristics, accuracy, print paper, etc. Make sure to test print and check.


<When publishing to the Web>

When publishing to the Web using services such as illustration sites, accuracy cannot be expected as multiple factors of the viewing environment such as the OS, browser, and monitor will differ from the original environment.

As a result, there is no need to embed a color profile with CLIP STUDIO PAINT unless you want accurate color reproduction.


<When collaborating with others>

When working with others, it is better to maintain the same RGB profile as each monitor environment and application will differ.

To prevent color differences, sRGB profiles are recommended as a general color gamut. In environments above Widows Vista, please set the monitor profile to sRGB as well.

However, color reproduction may be difficult due to different monitor models and external environments such as lighting.


【POINT: Factors other than color profiles that affect color matching】

When the display and output colors are different even after setting a color profile, the following may be the reason.


<Device settings, individual differences>

If the monitor device settings are changed for instance, the displayed results will be different. Even when using the same product, a complete replication of colors may be difficult as each device is different due to factors such as aging.

While removing these factors is difficult, adjustments and maintenance such as reviewing the device settings, monitor calibration, and cleaning the print head may merit better results.

For more information, refer to each devices’ manual.


<Different external environments>

The appearance of colors change based on things such as brightness of the monitor or viewing environment of the print results. This may be averted by adjusting the surrounding lights or using a monitor hood.

To perform more precise color adjustments, you will need to consider introducing a calibration tool or a monitor with color management functions. As they are expensive, they are unnecessary for the hobbyist.


[3] Preferences

From here, we will introduce useful information for using color profiles in CLIP STUDIO PAINT.


Let’s start by explaining the color profile related items that can be set in CLIP STUDIO PAINT’s [Preferences].


Select the [File] menu ([CLIP STUDIO PAINT] menu on macOS) → [Preferences], and open the [Preferences] dialog box to select [Color conversion].


① RGB profile

Set the CLIP STUDIO PAINT default RGB profile. By default, the OS specified monitor profile will be selected.

When changing profiles in the [Preferences] dialog, the selected profile will be used, regardless of the OS specified profile.


When creating a new file or opening an image without a color profile, the OS specified RGB profile will be used as the default preview profile.

If the OS specified profile cannot be accessed, the RGB profile specified here will be set as the default preview RGB profile.


Unless you are using a multi-monitor environment with separate profiles for each monitor, normally you do not need to change these settings.


【POINT】 OS specific monitor profiles

Versions beyond Windows Vista ...... Profile specified in [Control panel]→[Display]→[Screen resolution]→[Advanced]→[Color management]

Versions beyond Windows 10 ...... Profile specified in [Settings]→[System]→[Display]→[Display adapter properties]→[Color Management]

macOS ...... Profile specified in [System preferences]→[Display]→[Color] (When specifying Apple default profiles such as “Color LCD” or “Cinema Display”, they will be displayed as “Display” in CLIP STUDIO PAINT).


② CMYK profiles

Set the default CMYK profile. This will be used when embedding or setting up a CMYK profile. “Japan Color 2001 Coated” will be selected by default.

For the types of color profiles, refer to [5] Common color profiles.


③ Rendering-Absicht

Set the default rendering intent. The contents are the same as the preview of the color profile settings.


④ Library to use

This is only available in a Windows environment. Select the default color conversion library. The contents are the same as the preview of the color profile settings.


[4] Opening an image embedded with a color profile.

CLIP STUDIO PAINT can open .jpg, .tif, .psd, and .psb files made in other applications or environments.

Depending on each color mode and profile, a file’s behavior and necessary profile upon opening will differ.


<RGB color>

When a profile is not embedded, colors will not be converted. RGB values will be displayed according to the OS specified monitor profile.

Even when profiles are embedded, the RGB values will be displayed according to the OS settings. However, the embedded profile will become the default values for the preview settings’ profile settings.


<CMYK color>

When there is no embedded profile, the preferences’ CMYK profile will be treated as such, and be converted to the preferences’ RGB profile.

When there is an embedded profile, the profile will be converted to the preferences’ RGB profile. Also, the embedded profile will become the default “Profile for preview” in the preview settings.


<Grayscale>

Regardless of a profile, it will be imported as having no profile.


[5] Common color profiles

The following are common color profiles.

Other than the ones presented here, there are other common profiles, like profiles provided by manufacturers of devices such as monitors and printers, and profiles customized by users.


Some device dependent profiles many not be available for input or output.

When a profile that cannot be used in CLIP STUDIO PAINT is selected, it will be replaced with the profile set in the preferences.



■ RGB data color profiles


<sRGB>

The “standard” RGB profile. It was created by Microsoft.

While it was intended for CRT monitors, it can also be used for various LCD monitors, digital cameras, scanners, and inkjet printers.


<Adobe RGB>

A profile provided by Adobe. Intended for professional photography and films, it can handle a wider color gamut than sRGB or Apple RGB. However, general LCD monitors cannot display every color in Adobe RGB.



■ CMYK data color profile


<Japan Color 2001 Coated>

A profile provided by the Japan Printing Machinery Association (JPMA).

Compatible with Japan’s inks, it is widely used when printing on coated paper, etc. This includes fanzine covers and postcards.


<Japan Color 2001 Uncoated>

Compatible with Japan’s inks, it is used when printing on high-quality paper. Common uses are the main pages of fanzines and color pages.

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