HYPERSPECTRAL IMAGING FOR COLOR AND SURFACE CHARACTERIZATION

Hyperspectral imaging for color and surface characterization

A hyperspectral camera is the most accurate imaging technique to inspect and measure colors as it records the full visible spectrum in each image pixel.

This information can be used to precisely identify and quantify the colors present in the object, including subtle color variations that may be imperceptible to the human eye. In the visible region, a very high separation of colors can be achieved.

In addition to measuring the color of an object, hyperspectral imaging can also provide information on the composition of the object and its surface properties, making it a powerful tool in many applications, including color matching, quality control, and product inspection.

Display inspection with a hyperspectral camera

Most display panels and light sources are based on LED backlights. They produce inconsistent spectra; therefore, accurate color measurement is only possible by measuring the actual spectrum.

Traditionally it is done by point spectrophotometers. Point spectrophotometers typically measure the spectral properties of light at a single point or small area, which can limit their ability to analyze spatial variations in color or surface properties. The inspection is limited to a few discrete points on the display surface in the production environment.

In contrast, hyperspectral cameras capture images over a large area, providing detailed information to analyze the variations in color and surface properties. The Specim FX10 hyperspectral camera can perform 100% display surface testing at a production test station in real time. Both luminance uniformity and color gamut can be inspected from the data to detect any color variations, inconsistencies, defects, or irregularities in the display, such as dead pixels or damaged areas.

Color control in digital printing

Digital printing is applied to paper, packaging, plastics, textiles, ceramics, and metal (like cans) products and is growing rapidly. Printer control requires frequent accurate measurement of color test sheets and also real-time in-line color measurement. Standard RGB cameras and multiband cameras are not accurate enough, and point-spectrometer-based XY scanners are too slow. The Hyperspectral color scanner based on Specim FX10 hyperspectral camera and intense LED illumination solves these issues. The line scan concept also applies to in-line applications.

Color measurement setup with Specim FX10 and LabScanner 40x20

Figure: Hyperspectral color scanner based on Specim FX10 hyperspectral camera