Multispectral imaging

Multispectral imaging captures image data within specific wavelength ranges, revealing details beyond human vision. 

Combining cameras with filters or specific illumination systems, this technique finds applications in remote sensing, medical imaging or cultural heritage preservation, among many others. It typically involves 3 to 15 spectral bands, while hyperspectral imaging extends this up to 200 bands.

Multispectral imaging systems typically use a camera with a filter wheel, a CMOS sensor with multiple filters, or multiplexed illumination based on LEDs, allowing each wavelength to be captured in turn. This process is repeated for all the desired wavelengths, resulting in a multispectral image.

Multispectral imaging has a wide range of applications, including:

• Remote sensing: Used to map vegetation, water, and other features from space.
• Medical imaging: Helps in the diagnosis of diseases, such as cancer, by identifying changes in the spectral signatures of tissues.
• Cultural heritage: Multispectral imaging can be used to examine paintings, artefacts, and other cultural objects without damaging them.
• Security: Explosives, and other dangerous chemical compounds, can be detected by means of multispectral imaging.

Both multispectral and hyperspectral imaging can also be used to measure colour in a variety of ways. One common approach is to use a technique called spectrophotometry. Spectrophotometry measures the amount of light reflected or transmitted by a sample at different wavelengths. This information can be used to calculate the colorimetric properties of the sample, such as its hue, saturation, and lightness.

Multispectral imaging can be used to measure colour in a variety of applications, including colour matching, colour inspection and colour identification.