Application of Hyperspectral Imaging: Component Color Difference Testing

This experiment explores the entire process of evaluating color differences in plastic casings of electronic components using hyperspectral color measurement equipment.

This experiment explores the complete process of using a hyperspectral color measurement system to evaluate color differences in plastic casings of electronic components.

Testing Environment

Firstly, we place the plastic shells to be tested one by one on a horizontal displacement platform in the darkroom. A strip halogen lamp is arranged at the top of the darkroom as illumination. While the platform moves at a constant speed, a hyperspectral camera covering 400-1000nm with a spectral resolution better than 2.8nm collects complete spectral images in a linear sweep manner; All Lab calculations use a parameter combination of D65 light source and 2 ° viewing angle.

The plastic casings to be measured were individually placed on a horizontal translation stage inside a darkroom. A halogen strip lamp was installed at the top of the darkroom to provide uniform illumination. While the stage moved at a constant speed, a hyperspectral camera covering 400–1000 nm with a spectral resolution better than 2.8 nm captured complete spectral images in a push-broom scanning mode. All Lab value calculations were performed using the D65 illuminant and a 2° standard observer angle.

Equipment specifications and parameters

Spectral range: 400~1000nm

Spectral resolution: ≤ 2.8nm

Number of spectral bands: 256

F数： F/2.6

Number of spatial pixels: 320

Detector type: CMOS

Detector interface: GigE

Effective bit depth: 12 bits

Equipment Specifications

- Spectral Range: 400–1000 nm

- Spectral Resolution: ≤ 2.8 nm

- Number of Spectral Bands: 256

- F-Number: F/2.6

- Spatial Pixels: 320

- Detector Type: CMOS

- Interface: GigE

- Effective Bit Depth: 12 bits

Hyperspectral Image

Spectral curves

Lab Values

The test conclusion is OK, indicating that the ∆ E calculated for the current selection is less than 0.5

The test conclusion NG indicates that the ∆ E calculated for the current selection is greater than 0.5

- OK: Indicates that the calculated ∆E of the current region is < 0.5

- NG: Indicates that the calculated ∆E of the current region is > 0.5

Interpretation standard for Δ E value:

0-1: Color differences that are almost imperceptible to the human eye.

1-2: Only trained individuals can perceive subtle differences.

2-3: Even untrained individuals can perceive slight color differences.

3-6: Obvious color differences.

6-12: Strong color differences.

>12: Different colors

∆E Interpretation Criteria:

- 0–1: Color difference is virtually imperceptible to the human eye.

- 1–2: Only trained observers can detect slight differences.

- 2–3: Untrained individuals can perceive minor color variations.

- 3–6: Clearly visible color difference.

- 6–12: Strong color difference.

- >12: Colors are completely different.

Summary/Conclusion

Through the reflectance curve, it can be seen that the curves of each sample are not the same. At the same time, the human eye can distinguish color differences in hyperspectral images, and the Lab value calculation results also indicate that there are significant color differences among the samples.

The reflectance curves show distinct spectral characteristics for each sample. Color differences are visually discernible in the hyperspectral images, and the calculated Lab values further confirm significant color variations among the samples.