Converting Icc Profiles To Camera Raw: A Quick Guide

ICC profiles are used to ensure that an image appears the same across different devices. However, using ICC profiles for RAW development has several drawbacks. For instance, it is not defined where in the development process the ICC profile should be applied, and ICC profiles cannot adjust to different illuminants (white balance). As a result, some software, such as Rawstudio 2.0, has implemented Adobe's DNG Color Profiles (DCP) specification, which defines the entire process of transforming RAW input data to a known colour space. Nevertheless, it is still possible to convert between ICC and camera RAW formats using certain software and scripts.

Using ICC profiles for RAW development

These limitations make it challenging to achieve consistent results when using ICC profiles across different applications. However, ICC profiles are still valuable for various purposes, and they can be beneficial in specific contexts.

When working with RAW images, it is essential to understand the colour correction process and the role of ICC profiles. While ICC profiles have their limitations, they can be utilised effectively by photographers and photo editing software to achieve the desired colour output.

To address the drawbacks of ICC profiles in RAW development, alternatives such as Adobe's DNG Color Profiles (DCP) have been introduced. DCPs offer a more standardised approach to transforming RAW input data into a known colour space. They provide a base adjustment before any changes are made to the image and a "look" part that applies a specific appearance. Additionally, DCPs can accommodate different illuminants, enhancing their flexibility.

When deciding whether to use ICC profiles or alternative options like DCPs for RAW development, it is crucial to consider the specific requirements of the project, the desired level of colour accuracy, and the compatibility with the software and hardware being used.

Pros and cons of using ICC profiles

ICC profiles are necessary for anyone using different devices to view the same file. Without them, your colours and images will change between digital devices and printers. ICC profiles help you calibrate your printer and your monitor to achieve a consistent colour output across different devices and media. They also help you preview how your document will look when printed, and correct any colour issues before printing.

Pros of Using ICC Profiles

ICC profiles ensure that when your file moves across different devices, your colours stay the same. They help you achieve a more professional look for your photos, graphics, or other documents. They also ensure that the colours on your screen match the colours on your paper, regardless of the lighting or viewing angle. This reduces the risk of colour fading or shifting over time and allows you to share documents with others, expecting them to see the same colours as you.

Cons of Using ICC Profiles

Using ICC profiles for colour accuracy and consistency can be challenging. You must create a different profile for each printer, paper, and ink combination you use and switch between them accordingly. Additionally, you must regularly update your profiles as the printer, paper, and ink may change due to usage, storage, or environmental factors. Furthermore, you must ensure that your monitor is calibrated and profiled since it affects how you view and edit documents on the screen. Lastly, it is important to understand the basics of colour management and the settings of your printing software as they may affect how your profile works in conjunction with other profiles.

Using DNG Color Profiles

DNG Color Profiles (DCP) are a new type of profile that defines a fixed way of transforming RAW input data to a known color space (Prophoto RGB). It is made up of two main parts: a base adjustment that is applied before any changes are made to the image, and a "look" part that applies a certain look to the image.

DCP profiles are tailored to specific camera models and are designed to improve color accuracy and consistency. They can be particularly useful when shooting in different lighting situations, such as a wedding or a virtual tour, where the color spectrum of the light can vary significantly between indoor and outdoor settings.

To create a DCP profile, you will need to use a color calibration chart, such as the X-Rite ColorChecker Passport, and take a photo of this chart in the same location as your normal photos. This will allow you to generate a DCP profile that can be used to achieve correct and consistent colors and white balance across all your shots.

When using DCP profiles, it is important to note that they are applied at the beginning of the image processing pipeline, as most tools depend on them. Additionally, DCP profiles offer a choice between single-illuminant and dual-illuminant options. Single-illuminant profiles are tailored only to daylight, while dual-illuminant profiles are designed for both daylight and incandescent light, providing better performance in most lighting situations.

DCP profiles can be created using software such as X-Rite ColorChecker Passport or open-source tools like DCamProf. DCamProf is a free and open-source command-line tool that can generate high-quality, smooth LUT profiles and is capable of generating profiles in both ICC and DNG formats.

When choosing between DCP and ICC profiles, it is worth considering the drawbacks of ICC profiles for RAW development. ICC profiles do not have a defined place in the development process, leading to inconsistencies. They also cannot adjust to different illuminants and may remove data such as highlight recovery information. Therefore, DCP profiles are generally preferred for raw development due to their specificity and ability to handle different lighting conditions.

In summary, DNG Color Profiles (DCP) offer a more advanced and flexible approach to color management in raw image processing. By creating custom profiles tailored to specific camera models and lighting situations, photographers can achieve accurate and consistent colors in their images. DCP profiles are widely supported by software applications and provide a reliable solution for managing color in raw photography.

Converting to another profile

ICC profiles are used to ensure that an image appears the same on different devices and when printed. However, there are some drawbacks to using them for RAW image development. The first is that it is not defined where in the development process the ICC profile should be applied. Secondly, it is unclear which aspects of the colour correction the ICC profile should address.

ICC profiles are also unable to adjust to different illuminants (white balance) and can only match one illuminant the best. Some profiles also incorrectly correct defects in software, such as missing gamma awareness. Finally, ICC profiles may remove data such as highlight recovery information.

Due to these issues, it can be difficult to make ICC profiles work consistently across different applications. This is where DNG Colour Profiles (DCP) come in. DCPs are a subset of the DNG specification and define a fixed way of transforming RAW input data to a known colour space (Prophoto RGB). They consist of two main parts: a base adjustment that is applied before any changes are made to the image, and a "look" part that applies a certain look to the image.

DCPs also have the advantage of being able to support two profiles for different illuminants. Depending on the actual illuminant (based on white balance), the profile that will be used is created by interpolating between the available profiles. Adobe profiles usually include a profile for illuminant A (Incandescent/Tungsten, 2856K) and D65 (Noon Daylight, 6504K).

To convert to a DCP, you can use the DCP profiles that Adobe includes in their Adobe DNG Converter (available for Windows and Mac). Once installed, you can find the profiles in "\Documents and Settings\All Users\Application Data\Adobe\CameraRaw\CameraProfiles". Simply copy all of them to the folder above and Rawstudio will automatically match them to your camera.

You can also use the Profile Editor Adobe has released (Windows/Mac) to create your own profiles, or buy the X-Rite ColorChecker Passport to create custom profiles.

Using ICC profiles for colour management

ICC profiles are an essential aspect of colour management, providing a precise characterisation of a colour input or output device, or a colour space. They are defined by the standards set by the International Color Consortium (ICC) and outline the colour attributes of a device or viewing requirement by mapping the device source or target colour space to a profile connection space (PCS). This PCS is either CIELAB (L*a*b*) or CIEXYZ.

The process of colour management involves several steps, and ICC profiles play a crucial role in ensuring accurate colour reproduction. Here's an overview of how ICC profiles are used for colour management:

Input Profiles:

Input profiles are used for devices such as digital cameras and scanners. To create an input profile, the device is set to a repeatable state, and a physical profiling target is captured as an image. This target image is then analysed, and a transformation table is created to translate between the device's RGB values and the known L*a*b* values from the target reference file. This results in an ICC input profile that can be assigned to any capture or scan made using the device. When opening an image, the input profile ensures accurate colour appearance on screen through a transformation using the input profile, display profile, and the chosen working colour space profile.

Display Profiles:

Display profiles are another type of device colour space and are crucial for accurate colour management. They are created by using a screen sensor to assess the display system's capabilities and build an ICC profile. This process involves calibrating the system and then measuring the calibrated appearance to create the profile. The resulting display profile, along with the appropriate OSD settings, helps achieve a good setup for accurate colour representation on the screen.

Output Profiles:

Output profiles are used for devices like inkjet printers and printing presses. To create an output profile, specific settings are chosen, and test prints of colour patches are made. These test prints are then measured using a spectrophotometer, and the measured data is analysed to create an accurate device characterisation or ICC output profile. This profile is then used by colour management applications to adjust image data sent to the printer, ensuring accurate reproduction within the printer's gamut.

Soft Proofing:

Good printer profiles can also be used for soft proofing, which is a way to predict printed output on a calibrated and profiled display screen. This process involves passing the original file's values through the printer profile and the display profile to simulate how the image will look when printed.

Using ICC Profiles for Conversion:

ICC profiles are essential for converting between different colour spaces. For example, when converting from an RGB colour space to a CMYK colour space, the first step is to obtain the ICC profiles for both spaces. Each RGB triplet is then converted to the Profile Connection Space (PCS) using the RGB profile. If needed, the PCS is converted between CIELAB and CIEXYZ. Finally, the PCS is converted to the CMYK values using the second profile.

Frequently asked questions