Recent developments in hyperspectral sensors have made it possible to acquire HyperSpectral Images (HSI) with higher spectral and spatial resolution. Hence, it is now possible to extract detailed information about relatively smaller structures. Despite these advantages, HSI suffers from many challenges also, like higher spatial variability of spectral signatures, the Hughes effect due to higher dimensionality, and a limited number of labeled training samples compared to the dimensions of the spectral space. Superpixels can be a potentially effective tool in tackling these challenges. Superpixel segmentation is a process of segmenting the spatial image into several semantic sub-regions with similar characteristic features. Such grouping by similarity can significantly ease the subsequent processing steps. Because of this, superpixels have been successfully applied to various fields of HSI processing like Classification, Spectral Unmixing, Dimensionality Reduction, Band Selection, Active Learning, Denoising, and Anomaly Detection. This paper focuses on Classification, presenting a detailed survey of superpixel segmentation approaches for the classification of HSI. The Superpixel creation algorithm framework and post-processing frameworks for superpixels in HSI are also analyzed. Also, a brief description of various application areas of superpixels is provided. An experimental analysis of existing superpixel segmentation approaches is also provided in this paper, supported by quantitative results on standard benchmark datasets. The challenges and future research directions for the implementation of superpixel algorithms are also discussed.

A hyperspectral image (HSI) is a collection of several narrow-band images that span a wide spectral range. Each band reflects the same scene, composed of various objects imaged at different wavelengths; the spatial information, however, remains generally consistent across bands. Both types of information, spectral and spatial, can be leveraged to identify and classify objects. Recently, the use of machine learning (ML) in object classification has become increasingly widespread. Regardless of the selected approach, object-specific spectral and spatial information is key to discriminating relevant categories. Whereas spatial information is usually repeated across bands, spectral information tends to be distributed more unevenly and often highly so. This poses the issue of removing redundancy, which is commonly called the band selection ( BS ) problem and refers to identifying an optimal subset of bands for further HSI processing.

The hyperspectral images (HSIs) often suffer from Hughes effect, as it records information of a single scene in several spectral bands. This can be mitigated by reducing the dimension of HSI. A novel framework for hybrid band selection (BS) is proposed in this work. The proposed technique is a multi‐objective approach, which incorporates clustering (spectral) and intra‐band (spatially filtered) de‐correlation measure (Frobenius norm) as maximisation of two cost functions. Heuristic optimisers are very sensitive to their associated hyperparameters. So, in the proposed architecture, Jaya optimisation is used for BS, as it does not possess any algorithm‐specific control parameter. Spatial and spectral features are extracted for both BS and classification (using support vector machine) for evaluating the effectiveness of the proposed/ experimented approaches. The evaluated performance measures are overall accuracy, average accuracy, and kappa (K). The experimental result shows that the proposed BS approach is better or competent with other experimented state‐of‐the‐art methods. The advantages of the proposed framework can be stated as: (i) spectrally distinct and spatially invariant objective formulation; (ii) Jaya optimisation with minimal control parameters; (iii) optimised ranking for more accurate BS; and (iv) performing classification using spatial–spectral features for further band reduction with the desired accuracy.