The LAB color space defines colors in a three-dimensional model: Lightness (L), red–green axis (a), and blue–yellow axis (b). It's a globally recognized standard supported by most modern color measuring devices. CIELAB is a standardized, device-independent system designed to map all visible colors that the human eye can perceive.

The LAB color space uses three values to define any color, each representing a specific dimension:

L (Lightness): Ranges from 0 to 100. It measures the brightness of the color, where 0 is pure black and 100 is pure white.
A (Red-Green Axis): Ranges from approximately -96 to +127. Positive values represent red tones, while negative values represent green tones.
B (Yellow-Blue Axis): Ranges from approximately -96 to +127. Positive values represent yellow tones, while negative values represent blue tones.

A haze meter should be calibrated every 6 months, or more frequently if used for certain quality control processes.

Zero calibration of a hazemeter is a critical pre-measurement procedure to ensure the instrument’s accuracy by resetting its baseline to "zero" when no haze or light attenuation is present.

1. Align the hazemeter’s measurement window with air or a black background, ensuring no objects block the window.

2. Press the hazemeter’s zero calibration button and wait for the instrument to complete automatic calibration. At this point, the instrument should display a zero haze value and a zero light transmittance value.

3. Observe the instrument’s display to confirm the zero calibration result stabilizes near zero. If the zero calibration is inaccurate, repeat the above steps multiple times until the displayed haze and light transmittance values stabilize near zero.

Perform 0-degree calibration before testing, this eliminates inherent instrument drift, environmental interference, or residual signal errors, ensuring subsequent measurements of transparent/translucent samples (e.g., plastic films，pvc, glass, coating, displays and cosmetic packaging) are reliable. Correct for minor instrument deviations caused by long-term use, temperature changes, or power fluctuations.

Usually you will find haze and transmittance standards of ASTM D1003, ISO 13468, & JIS K7105.

Take L*a*b* readings of two samples using a colorimeter or spectrophotometer and calculate color difference using the 3 formula (Delta E). The difference in 0 is the reported Delta-E, which shows how visible the change is, whereas the thresholds define the acceptability as per the application requirements.

Replace when the total hours exceed rated life, decrease in brightness, or the color temperature shifts beyond tolerance.

A colorimeter is a quick and inexpensive method to measure color and to control color in a material or solution. It is used to maintain color consistency during production and to check the chemical concentration. It also assists with the quality control of labs, food, textiles, and pharmaceuticals.

Light booths and color matching are essential for the textiles, printing, automotive, plastics, cosmetics, and coatings industries. These fields rely on tight color alignment to protect brand value and meet global quality demands for color. 

An inappropriate viewing angle may lead to reflections or color shifts in the light. The correct angle of 45 or 0 will provide the real color of the assessment without the distraction of glare.

Techniques of measuring color are visual color comparison, colorimetry (with colorimeters) and spectrophotometry (measuring spectral reflectance), and image analysis. Both techniques measure the reflection or absorption of light by materials and are commonly quantified. Therefore standardized in color spaces such as CIELAB or RGB.