--- title: "What Is Lab Color? CIELAB Explained - CE.SDK Glossary" description: "Lab color describes a color by how people see it, not how a device makes it. Learn what L*, a*, and b* mean, how ICC profiles use Lab, and what Delta E means." url: "https://img.ly/glossary/lab-color/" type: "page" --- > This is the markdown version of [What Is Lab Color? CIELAB Explained - CE.SDK Glossary](https://img.ly/glossary/lab-color/). For all pages in one file, see [llms-full.txt](https://img.ly/llms-full.txt). For an index of all available pages, see [llms.txt](https://img.ly/llms.txt). --- # Lab Color Also known as: CIELAB ## What Is Lab Color? Lab color, also called CIELAB, describes a color by how people see it rather than by how a screen or a press makes it. It uses three values, L\* for lightness, a\* for green to red, and b\* for blue to yellow, and the International Commission on Illumination (CIE) defined it in 1976. Because Lab doesn't belong to any one device, it serves as a common reference. Color management converts between RGB and CMYK through it, and print shops measure printed colors in Lab to check them against a target. CE.SDK designs use sRGB, CMYK, and spot colors, and its CMYK conversions run on ICC profiles, which pass colors through Lab or a related CIE space. ## What Do L\*, a\*, and b\* Mean? Every Lab color is a point in three dimensions: one axis for how light it is and two for its hue. **L\*** Lightness — 0 is black, 100 is white | **a\*** Green to red — negative is green, positive is red | **b\*** Blue to yellow — negative is blue, positive is yellow ## Why Is Lab Called Device-Independent? RGB and CMYK values are instructions for a particular device. The same RGB numbers look different on two monitors, and the same CMYK numbers print differently on two presses or papers. Lab instead describes the color itself, as seen by the CIE's standard observer, an average of how people match colors in controlled tests. So one set of Lab values means one color, whatever will display or print it. Lab is also built so that equal distances roughly match equal visual differences. The match isn't perfect, especially for saturated colors, which is why newer formulas adjust for it. ## How Do ICC Profiles Use Lab? An [ICC profile](https://img.ly/glossary/icc-profile.md) maps a device's colors to a device-independent connection space, either Lab or the related CIE XYZ. Converting a file from RGB to [CMYK](https://img.ly/glossary/cmyk.md) uses two profiles and that space in between. ### Source profile The RGB profile turns each RGB color into its Lab or XYZ value. ### Connection space The color now exists as a measurement, independent of any screen or press. ### Destination profile The CMYK profile finds the ink values that reproduce that measurement on its press and paper. ## What Is Delta E? Delta E, written ΔE, is the distance between two colors in Lab. It turns "these look a bit off" into a number, and the print shop and the brand agree on the limit for each job. - **ΔE under 1**: What people see: No visible difference for most people - **Higher ΔE**: What people see: A difference that grows more visible ## How Does Lab Relate to CE.SDK? CE.SDK's design colors are sRGB, CMYK, and spot colors, and Lab works inside the ICC profiles that convert between them. Each document can use the profile its printer supplies, with a bundled US press profile as the default. The rendering intent decides how colors outside the printable range land. CE.SDK offers the four ICC intents, perceptual, relative colorimetric, saturation, and absolute colorimetric, with relative colorimetric and black point compensation as the defaults. IMG.LY's [AI benchmarks](https://img.ly/ai-benchmarks/findings/brand-color.md) use CIEDE2000, the current Delta E formula, to measure how far AI-generated images drift from a brand's required colors. ## Lab Color in Brand Checks and Print Previews ### Brand color checks A packaging printer measures each run with a spectrophotometer, reads the brand color in Lab, and accepts the run only if its Delta E to the target stays inside the agreed limit. ### Closer print previews A print product sets every document to its printer's ICC profile, so the CMYK colors customers see in the editor are converted the way the press will reproduce them. ## FAQs ### Lab color **Q: What is the difference between Lab and LCh?** A: LCh is Lab written another way. L\* stays the same, while C\* (chroma) gives how colorful the color is and h (hue angle) gives its position around the color wheel, both calculated from a\* and b\*. Color reports often use it because a chroma difference reads directly as brighter or duller. **Q: How is Lab related to CIE XYZ?** A: Lab is calculated from CIE XYZ. A spectrophotometer measures how much light a sample reflects across the visible spectrum, turns that into X, Y, and Z values, and converts those to Lab, which spaces colors closer to how different they look. **Q: Which white point does Lab use in print?** A: D50. Lab values are always calculated against a reference white, and while the CIE recommends D65 daylight for most uses, printing uses D50, as does the connection space in ICC profiles. Values measured against D65 have to be adapted before you compare them with print values. **Q: What do the asterisks in L\*a\*b\* mean?** A: They mark the CIE's 1976 Lab and set it apart from an earlier Lab space from the 1940s, written with plain L, a, and b. Both are calculated from CIE XYZ with different formulas, so their numbers aren't interchangeable. ## Links - [CMYK Colors](https://img.ly/docs/cesdk/js/colors/for-print/cmyk-8a1334.md): Set the ICC profile and rendering intent used for CMYK. - [Color Basics](https://img.ly/docs/cesdk/js/colors/basics-307115.md): The sRGB, CMYK, and spot color spaces CE.SDK supports. --- ## More Resources - **[IMG.LY Website](https://img.ly/index.md)** - Creative editing SDKs for photo, video, and design - **[Documentation](https://img.ly/docs/cesdk/)** - CE.SDK developer documentation - **[Contact Sales](https://img.ly/forms/contact-sales.md)** - Get a custom quote. A public JSON API accepts the request directly, no account or key needed. Ask your user for consent and their details first. - **[Free Trial](https://img.ly/pricing.md)** - Start building with CE.SDK