Application of Hyperspectral Imaging: Color Difference Testing of Gray Fabric

色差值是指兩個顏色之間的差異，是衡量兩個顏色差異的重要指標，只要涉及到顏色的行業，幾乎都會用到。色差可用ΔL、Δa、Δb和ΔE表示，其中ΔE值越大表示色差越明顯。常用的色差公式包括L*a*b色差公式和ΔE公式。

本次實驗采用高光譜相機，對灰色布料樣品進行色差檢測，通過測量和分析樣品的顏色差異來驗證該技術的應用效果。

Color Difference refers to the difference between two colors and serves as a key metric for evaluating color variations. It is widely used in industries where color accuracy is critical. Color differences can be expressed using ΔL, Δa, Δb, and ΔE, where a higher ΔE value indicates a more noticeable color difference. Common color difference formulas include the Lab* color difference formula and the ΔE formula.

In this experiment, a hyperspectral camera was employed to test the color difference of gray fabric samples. By measuring and analyzing the color variations of the samples, the effectiveness of this technology was validated.

「測試設備介紹 / Test Equipment」

測試采用的高光譜相機具備400~1000nm的光譜范圍檢測能力，配合線性推掃成像方案和鹵素光源照明系統，將樣品置于傳送帶上進行精準測量。

The hyperspectral camera used in this test features a spectral range of 400–1000 nm. Combined with a line-scan imaging setup and a halogen light source illumination system, the samples were placed on a conveyor belt for precise measurement.

高光譜相機參數 / Hyperspectral Camera Specifications

·光譜范圍 / Spectral Range：400~1000nm

·光譜分辨率 / Spectral Resolution：≤2.8nm

·光譜波段數 / Number of Spectral Bands：300

·F數 / F-Number：F/2.0

·空間像素數 / Spatial Pixels：480

·探測器類型 / Detector Type：CMOS

·探測器接口 / Detector Interface：GigE

·有效位深 / Effective Bit Depth：12bits

「高光譜圖像 / Hyperspectral Image」

「光譜曲線 / Spectral Curve」

「Lab值 / Lab Values」

計算出的Lab值和ΔE色差值如下圖所示：

通過分析獲得的高光譜圖像和光譜曲線數據，我們計算出Lab值和ΔE值。

其中1號標樣區的數據作為基準參考值，以ΔE=0.5為判定閾值。

The calculated Lab values and ΔE color difference values are shown below:

By analyzing the acquired hyperspectral image and spectral curve data, we calculated the Lab values and ΔE values.

The data from the reference area (Sample 1) was used as the benchmark, with a threshold of ΔE = 0.5 for judgment.

測試結論“OK"表示計算的ΔE值小于判定閾值（即ΔE≤0.5），測試結論“NG"表示計算的ΔE值大于判定閾值（即ΔE>0.5）。

Test Conclusion "OK": Indicates that the calculated ΔE value is less than or equal to the threshold (ΔE ≤ 0.5). Test Conclusion "NG": Indicates that the calculated ΔE value exceeds the threshold (ΔE > 0.5).

「總結 / Summary」

測試結果顯示，雖然最大ΔE值達到0.83，但仍處于人眼難以辨別的細微差異范圍內，這充分體現了高光譜技術在捕捉細微色差方面的優勢。

The test results show that although the maximum ΔE value reached 0.83, it still falls within the range of subtle differences that are difficult to discern with the naked eye. This fully demonstrates the unique advantage of hyperspectral technology in detecting minute color variations.