Q14,paper3,J 12. If the pixels of an image are shuffled then the parameter that may change is

Options (A) Histogram (B) Mean (C) Entropy (D) Covariance
Answer(D) Co variance.
Entropy can be described as a measure of the amount of disorder in a system. An organized structure, such as a crystal or a living organism, is very highly ordered and consequently has low entropy. When the crystal is heated sufficiently, it melts and becomes liquid, a much less ordered state. When the organism dies, it decays and becomes completely disrupted. In either system, its entropy increases. Another way of expressing entropy is to consider the spread of states which a system can adopt. A low entropy system occupies a small number of such states, while a high entropy system occupies a large number of states. In the case of an image, these states correspond to the gray levels which the individual pixels can adopt. For example, in an 8-bit pixel there are 256 such states. If all such states are equally occupied, as they are in the case of an image which has been perfectly histogram equalized, the spread of states is a maximum, as is the entropy of the image. On the other hand, if the image has been thresholded, so that only two states are occupied, the entropy is low. If all of the pixels have the same value, the entropy of the image is zero. Histogram of an image , like other histograms also shows frequency. But an image histogram , shows frequency of pixels intensity values. In an image histogram, the x axis shows the gray level intensities and the y axis shows the frequency of these intensities. The different remote-sensing-derived spectral measurements for each pixel often change together in some predictable fashion. If there is no relationship between the brightness value in one band and that of another for a given pixel, the values are mutually independent; that is, an increase or decrease in one band’s brightness value is not accompanied by a predictable change in another band’s brightness value. Because spectral measurements of individual pixels may not be independent, some measure of their mutual interaction is needed. This measure, called the covariance. so it is co variance that decides the relationship , what will be effect if one pixel is changed.