MSI – Building the Cube

In this class, we show how to build the spectral cube, the actual data cube used for multispectral analysis.

This folder contains all the images that were created and edited up to the final calibration step. These images have already been registered and calibrated, and it is essential that the processing steps are followed in the correct order. One important requirement is that all images must be grayscale. They should not be color JPEG images, but true grayscale images.

You can easily verify this using image-editing software such as GIMP. For example, we open one of the images—here, the 405 nm band. Once the image is loaded in GIMP, we go to Image → Mode and confirm that the image is set to Grayscale, not RGB. This check ensures that the data are suitable for cube construction.

At this point, we open the Hypercube software and begin loading the images. The process is somewhat manual, as each image must be loaded individually. We start by selecting File → Open and load the first image, corresponding to 405 nm. Once the image is open, we go to Image → Convert Image Plane to Cube. A new window appears titled Cube. At this stage, the cube contains only one plane.

We then close the 405 nm image and load the second image, 430 nm. After opening it, we select Image → Add to Cube. Since the cube already exists, we add this image as the last band. The cube now contains two planes.

We repeat the same procedure for the remaining images—450 nm, and so on—until all bands are added. By the end of the process, the cube will consist of 18 image planes, each corresponding to a different spectral band.