Contrast enhancement of IRS-1C LISS data

Histogram modification technique is regularly applied to improve contrast and feature discrimination. The spectral components of any feature are mutually dependent and any histogram overlooking this aspect will not provide scope for multispectral data utilisation. The remote sensing satellite IRS-1C has three sensors on board, namely, Wide Field Imaging Sensor (WIFS), LISS-III and PAN Sensor, with varying spatial and spectral resolutions. The maintenance of relative intensity levels is a major casuality in the case of histogram equalization of low contrast images of high resolution sensor LISS-III. This results in some sort of defocussing of image for low contrast original data. An approach that is possible to apply without causing any image with patchiness is described. Basically, the idea underlying this approach is to perform three independent transformations on the gray level of any input pixel and manipulate the histogram while performing the histogram equalization. Thus the approach adopted in the study is supposed not to alter the spectral signature as may be possible in automated histogram equalization.