Image cube

Further processing is also usually performed to transform the reflectance image cube to its logic (UR) form, which is effectively the sample absorbance . This results in chemical images in which brightness linearly maps to the analyte concentration, and is generally more useful for comparative as well as quantitative purposes. Note that for NIR measurements of undiluted solids the use of more rigorous functions such as those described by Kubelka and Munk are usually not required. ... 

Compute arithmetic operations on individual images, spectra, or entire image cubes... 

Perform Savitsky-Golay smoothing with derivatives on individual spectra or entire image cubes Spatially interpolate... 

Bin individual images or entire image cubes to improve signal noise ratio... 

Figure 43. Schematic of an image cube collection with a NIR-Cl instrument. The data cube is constructed plane by plane, where each plane contains the spectral information at one wavelength (A.) for all spatial positions (Xj, yi) in the field of view.

Spectral correction involves taking the ratio of the data to a background reference in order to remove the instrument response component. Because the filter-based NIR-CI instruments operate in a true staring or DC mode, it is also necessary to subtract the dark camera response from the image cube. The correction to reflectance (R) is therefore ... 

It is also possible to produce a four-dimensional data cube by adding a third spatial coordinate. This is achieved by physically sectioning a sample and acquiring multiple image cubes along the depth of the sample. An example of such an approach is shown later in this chapter where the three-dimensional chemical image of a corn kernel is examined. 

Figure 4.3.3, A and B, shows a typical NIR chemical image and a reflectance spectrum acquired in the hard endosperm structure of the kernel. Although each image cube visualizes the biochemical composition of specific morphological structures at each physical depth into the sample, all of the data sets can also be assembled to constmct an image of the three-dimensional distribution of the chemical components of interest. The individual image cubes are first processed, using a commercially available software package (ISys 3.0, Spectral Dimensions, Ine.), by first subtracting...

Figure 1 Mapping and imaging data can be depicted as an image cube having two spatiai and one spectrai dimensions.

FIGURE 1.4. Mirror-image cubes with inversion symmetry. See color insert. 

Mirror-image cubes with inversion symmetry... 

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