What is the machine used to measure color?

The machine used to measure color is primarily called a colorimeter or spectrophotometer. 

Spectrophotometer: The most common and precise type. It analyzes light reflected/transmitted by an object across the visible spectrum to quantify color accurately. A spectrophotometer can measure colors on smooth or matte surfaces, as well as textured, glossy, mirror-like surfaces, and special effect colors. It measures the reflected light of a sample at a fixed angle (e.g., 45˚) or captures light reflected at all angles to calculate color measurements that closely match what the human eye perceives. Additionally, similar to how humans flip a sample to view colors from different angles, a spectrophotometer is suitable for measuring a variety of materials and surface characteristics. Widely used in industries like paint, textiles, plastics, Chemicals, Pharmaceuticals, and printing. 

Colorimeter: Also called photoelectric integrating colorimeter, a simpler, more cost-effective option. It measures color based on three primary colors (RGB) and is suitable for basic color matching needs. A photoelectric integrating colorimeter is a color measurement device based on the photoelectric integration principle. It directly measures the tristimulus values XYZ of an object's color using three color filters (red, green, blue) and silicon photocells as three sensors. The color measurement principle of this instrument imitates the human eye's mechanism of perceiving the three primary colors (red, green, blue). It corrects the relative spectral sensitivity of the detector through color filters to match the CIE-recommended spectral tristimulus value functions x(λ), y(λ), and z(λ).

Spectrocolorimeter: Combines the functions of spectrophotometers and colorimeters, offering both spectral data and color space values for comprehensive analysis.