Sharif Digital Repository

Spectral Images, and Hyperspectral images as one of their main subsets, has been widely utilized in many scientific fields in recent years. Spectral unmixing may be regarded as one the main problems in hyperspectral image processing. Determining constituent materials (Endmembers) and their respective proportions(Abundance) is the main goal of spectral unmixing. Classic methods which are available for spectral unmixing mainly consist of two major separate steps for endmember extraction and abundance estimation. To combine these two steps in one, recently, powerful signal processing tools such as Independent Component Analysis (ICA), Nonnegative Matrix Factorization (NMF), and Sparse Component... 

We present a new high signal to noise ratio spectroscopic survey of the Northern hemisphere to probe the Local Bubble and its surroundings using the 5780Å and 5797Å Diffuse Interstellar Bands (DIBs). We have observed 432 sightlines to a distance of 200 pc over a duration of 3 years. In this study, for both inside and outside the Local Bubble, we establish the 5780and 5797correlations with Na i, Ca iiand E(B-V). The correlations show that among all neutral and ionized atoms, the Na ihas more similarity with 5780and Ca iihas strong correlation with 5797, which suggest that the ionization level of 5797is more than 5780. We study the 5780correlation with 5797, which shows a tight correlation...