Device-dependent digital colour spaces
- Device-dependent means the colours selected on-screen during production and editing are not matched to the specific equipment used to reproduce them.
- Device-dependent means the digital colour space being used as part of a workflow does not know how an image will be used or what type of equipment it will be matched with.
- Device-dependent colour spaces use basic colour notation such as RGB decimal and hexadecimal values without determining the exact colours that will be selected by the equipment it is reproduced on.
- Common Device-dependent colour spaces include:
- RGB colour space
- HSB colour space
- CMYK colour space
Device-independent digital colour space
- A device-independent colour space is one where specified colours appear relatively the same regardless of the equipment used to reproduce them.
- Device-independent colour spaces are used to ensure colours appear consistent throughout a workflow and that colours can be accurately reproduced at the end of the process.
- An example of a device-independent colour space is the CIE Lab* colour space (known as CIELAB and based on the human visual system).
- Adobe 1998
- CIE Lab*
- sRGB (standard Red Green Blue) is a widely used colour space or standard for displaying images and colours on electronic devices, such as computer monitors, smartphones, and TVs.
- Colour Representation: In the sRGB colour space, each colour is represented by combining three primary colours: red, green, and blue. By varying the intensity of these three colours, a wide range of colours can be displayed.
- Gamma Correction: sRGB uses a gamma correction curve to ensure that the colours displayed on screens appear more natural to the human eye. Gamma correction adjusts the brightness levels to match how our eyes perceive light.
- Limited Gamut: While sRGB covers a broad range of colours, it has a relatively limited gamut compared to some other colour spaces. This means it may not accurately represent certain vibrant or intense colours found in the real world.
- Default Colour Space: Most electronic devices are set to use the sRGB colour space as the default, ensuring that images and colours look consistent across different screens.
- Compatibility: sRGB is widely supported by various software, web browsers, and devices, making it an excellent choice for sharing images and graphics online or for general purposes.
- Adobe RGB (Adobe 1998 or Adobe RGB 1998) is another widely used colour space, commonly used in the professional photography and printing industry.
- It was developed by Adobe Systems to offer a larger gamut than sRGB, making it more suitable for preserving and reproducing a broader range of colours, particularly vibrant and saturated colours found in some real-world scenes.
- Larger Gamut: Adobe RGB has a wider gamut compared to sRGB, meaning it can represent more colours. This expanded gamut is especially beneficial for capturing and preserving the vibrant colours seen in nature, such as deep greens, rich reds, and intense blues.
- Chromaticity Coordinates: The colour values in Adobe RGB are specified using chromaticity coordinates for red, green, and blue primaries. These coordinates determine the position of each colour in the colour space and define its hue and saturation.
- Suitable for Printing: Adobe RGB is often preferred for professional printing because it can retain a more extensive range of colours during the printing process, resulting in more accurate and vibrant prints.
- Less Common for Web and Display: While Adobe RGB is excellent for preserving colours in high-quality prints, it is less commonly used for web and digital display purposes. Some web browsers and software may not fully support Adobe RGB, leading to potential colour shifts if not handled correctly.
- CIE Lab* (CIELAB) is a device-independent colour space developed by the International Commission on Illumination (CIE).
- It is designed to represent all visible colours in a way that is consistent with human perception, making it an essential tool for colour-related applications, such as colour matching, colour conversion, and colour comparison.
- CIE Lab* is based on the concept of perceptual uniformity, which means that the numerical differences between colours in this space correspond to the perceived differences in the human visual system. In simpler terms, two colours that have the same numerical distance in CIELAB are visually perceived as equally different.
- CIE Lab* encompasses the entire range of human vision, covering all the visible colours, including highly saturated and vivid colours that cannot be fully represented in some other colour spaces.
- The asterisk (*) used in the name CIE Lab* distinguishes it from an earlier 1976 version.
- The Pantone colour system is widely used for mixing paint and defines a colour space by:
- Matching an existing colour or set of colours to Pantone colour swatches, or
- Choosing a set of colours from Pantone colour swatches
- Calibrating a paint machine (or another type of equipment) to accurately reproduce the colour of each swatch.