The LAB color, also called CIELAB color space, is a color space that describes all color perceptions visible to the human eye. It was developed by the International Commission on Illumination (CIE) in 1976, and has since been widely used in various applications, especially in the color and digital graphics industry.
Components of the Color LAB
The CIELAB has three components. Let us describe the characteristics of each of them:
*L (Luminance or Lightness)**
- Represents the luminance of the color.
- Values vary between 0 and 100.
- A value of 0 means absolute black, while a value of 100 indicates absolute white.
- Represents the green-red axis.
- Positive values of a* indicate red tones.
- Negative values of a* indicate green tones.
- Represents the blue-yellow axis.
- Positive values of b* indicate yellow tones.
- Negative values of b* indicate blue tones.
An important aspect of CIELAB space is that it was designed to be perceptually uniform. This means that a constant change in a value should be perceived as a constant change in color appearance. For example, a 10-unit change in the L* value should be perceived as a similar change in lightness, regardless of the initial L* value.
Where is CIELAB used?
The LAB color space is widely used in various industries and applications due to its design that seeks to represent the way the human eye perceives color. The following is an analysis of each of the industries in which this color space is used:
- Printing and graphic design: CIELAB is used for color specification, quality control and color management in devices such as printers, monitors and scanners. It allows designers and print technicians to compare and measure colors with an objective, standard reference.
- Textile and dye industry: To ensure color consistency in production batches and compare colors of different materials.
- Cosmetics and paint: To develop and compare shades, as well as to ensure color uniformity in different production batches.
- Food industry: The color of a food can influence the perception of its taste and quality. Color LAB can help in quality control and new product development.
- Dentistry: In esthetic dentistry, it is used to measure and compare the color of teeth and restorative materials.
- Agriculture: To assess the ripeness and quality of fruits and other agricultural products based on their color.
- Research: Used in studies that seek to understand and quantify human perceptions of color.
- Electronics: In the calibration of monitors and screens to ensure correct color representation.
- Digital photography applications: Some image editing programs offer the possibility of working in the LAB color space to make specific adjustments in brightness and color independently.
Advantages of Color LAB
One of the main attractions of LAB color is the multiple benefits it offers:
- Separation of luminosity and chromaticity: In CIELAB, luminosity (L*) is treated independently of color information (a* and b*). This makes it possible to edit the lightness of an image without affecting its hue and vice versa, which is especially useful in photo retouching and graphic design.
- Perceptually uniform: Although not perfectly uniform, CIELAB space was designed to be largely uniform. This means that a similar change in numerical values anywhere in the space should represent a perceptually similar change in color.
- Broad color representation: It was designed to encompass most (if not all) of the colors perceivable by the human eye.
- Device independence: Unlike other color spaces such as RGB or CMYK, CIELAB is not tied to a particular device. It is an absolute color specification, which means that a color in CIELAB will look the same regardless of the device, as long as that device can represent that color and is properly calibrated.
- Facilitates color comparison: Because it is a standard, objectively defined color space, it facilitates accurate color comparison in different contexts, such as in quality control in the printing or textile industry.
- Conversion to other color spaces: It is possible to convert colors between CIELAB and other color spaces more predictably than between spaces that are not perceptually uniform.
- Used in color difference formulas: Since CIELAB is a space that seeks to be perceptually uniform, it is the base space for many color difference formulas (such as CIEDE2000), which seek to quantify the perceptual difference between colors.
Limitations of CIELAB
Despite the many advantages of CIELAB, it also has certain limitations. We are going to point them out for you to take them into account, since it is essential to know them if you plan to work with this color space:
- It is not perfectly uniform: It was designed to be perceptually uniform, but in practice, it is not perfectly uniform. There are areas in the space where the numerical differences do not correspond exactly to the perceptual differences. This can lead to inaccuracies in certain color difference calculations.
- Out of gamut of many devices: CIELAB can represent virtually all colors visible to the human eye, yet many of these colors are outside the gamut (range of representable colors) of common devices such as monitors, printers and cameras.
- Computational complexity: Converting between CIELAB and other color spaces, such as RGB or CMYK, may require more complex calculations compared to other color systems.
- Not always intuitive: Although it separates brightness from chromaticity, for someone used to thinking in terms of RGB or CMYK, working in CIELAB may be less intuitive initially.
- Limitations in high-precision applications: In applications where extreme precision in color perception is needed, such as in scientific research or the paint industry, other models or variations of CIELAB are sometimes preferred, such as CIEDE2000, which adjusts for some of CIELAB’s non-uniformities.
- Observer and illumination dependence: CIELAB is device independent but still depends on standard observing conditions, such as the reference observer (usually the standard CIE 1931 2° observer or the CIE 1964 10° observer) and illumination conditions (e.g., D65 for daylight). Changing these conditions can change the LAB representation of a color.
These limitations do not detract from the value of CIELAB as a tool, but it is very important to be aware of them when using this color space in specific applications. The choice of a color space should always be based on the purpose and demands of the task at hand.
CIEDE2000 is a formula for calculating color difference developed by the International Commission on Illumination (CIE). This formula was designed to improve on the shortcomings of previous formulas based on CIELAB space. The main purpose of CIEDE2000 is to provide a metric that more closely resembles human perception of color differences.
Some key points that are important about CIEDE2000 are:
- Human Perception: Although the CIELAB color space is perceptually uniform in general, there are areas where it is not perfectly uniform. CIEDE2000 attempts to correct for these non-uniformities so that the color difference measurement is more consistent with human perception.
- Additional Corrections: CIEDE2000 introduces corrections for lightness, chromaticity and hue to improve color difference accuracy.
- Applications: Due to its improved accuracy over previous formulas, CIEDE2000 has become the standard in many industries that require accurate color difference measurements, such as the dye industry, paints, textiles, and more.
- More Complex: Compared to previous CIELAB-based color difference formulas, CIEDE2000 is computationally more complex. This can be a drawback in some contexts, but the improved accuracy usually justifies the increased complexity.