## 2 Materials and Methods
### Data Acquisition Systems and Calibration  
The VNIR hyperspectral images were acquired by a push broom line-scan VNIR HSI system in the spectral range of 400-1000 nm with a diffuse reflectance mode. The VNIR HSI system consisted of a spectrograph (ImSpector V10E, Specim, Oulu, Finland), a 12-bit CCD detector (SensiCam QE SVGA, Cooke Corp., Auburn Hills, MI, USA), an objective C-mount lens (Schneider, XENOPLAN, Bad Kreuznach, Germany), a pair of 50-W tungsten-halogen lamps (Photoflex, Watsonville, CA, USA), and a computer to control the camera and acquire images using HyperVisual application software (PhiLumina, Gulfport, MS, USA). The average spectral resolution was 1.27 nm, and the pixel resolution was about 0.37 mm/pixel. The lamps were positioned at about 45\({}^{\circ}\) angles at both sides, and the focus was set for the working distance of 350 mm. The camera exposure time was 45 ms. The on-camera binning was set to 2 (spatial) \(\times\) 2 (spectral). The resulting uncalibrated raw hyperspectral images acquired by the VNIR system had the dimensions of 688 (width) \(\times\) 500 (lines) \(\times\) 520 (calibrated wavelengths between 354 nm and 1018 nm). The SWIR system included a spectrograph (Hyperspec \({}^{\circled@}\)SWIR, Headwall Photonics, Fitchburg, MA, USA), a digital camera with a Peltier-cooled 320 \(\times\) 256 mercury-cadmium-telluride (MCT) detector (MCT-851 XC403, XenICs, Leuven, Belgium), an objective lens with a focal length of 30.7 mm (OLES30, Specim, Oulu, Finland), a motorized linear stage (TLSR300B, Zaber Technologies, Inc., Vancouver, BC, Canada), two MR-16 50-W tungsten halogen lamps with gold-coated reflectors with a 12V DC power supply, a computer, and custom application software. For acquiring SWIR hyperspectral images, the custom software developed in-house was used to control the line scan movement of translation stage and the MCT camera synchronously. The average spectral resolution was 7.4 nm. The pixel resolution was about 0.37 mm/pixel. The resulting uncalibrated raw SWIR hyperspectral image had the dimensions of 320 (width) \(\times\) 800 (lines) \(\times\) 256 (calibrated wavelengths from 848 nm to 2802 nm). Before the experiment, the instrument was commissioned to allow for spectral calibration and the correction of non-uniform, hot and dark pixels of MCT detectors. Light adjustment was made to the height and angle of the two halogen tungsten lamps to provide illumination evenly and minimize the shadow on the side of the samples. Each filter was  
Figure 1: Pictures of all FM samples used in this study: (**a**) 5 \(\times\) 5 mm\({}^{2}\) size and (**b**) 2 \(\times\) 2 mm\({}^{2}\) size of FMs. The information about the samples in the pictures is in Table 1, while the samples within a set (Set 1–6) were placed from left to right along a row in the pictures, they were listed from top to bottom in the table. placed on the translation stage, conveyed to the field of view of cameras with the adjusted speed, and scanned line by line. The raw intensity values (uncalibrated digital numbers) of the acquired hyperspectral images were calibrated using an intensity calibration technique. The intensity calibration based on white and dark references was done to all pixels of each raw hyperspectral image to minimize the uneven effects of light energy in different wavelengths and spatial locations. A white reference image was acquired with a diffuse reflectance panel with 99% reflectivity (Spectralon, Labsphere, North Sutton, NH, USA). A dark current image was obtained while blocking the camera lens with a lens cap. In the case of SWIR imaging, an in-field calibration was performed with horizontal stripes of dark (n = -70 lines) and white (n = -65 lines) reference images (2D spectral images) on top of each measured image. In other words, the reference images for the calibration of SWIR images were embedded in the images.