Briefly describe 
(a) the differences of isopreference curves between crowd and Lena’s face (5%), 
(b) the assumption for the degradation function and the added noise in the degradation model (5%)
(c) the differences between the band filter and the notch filter (5%),
(d) the mechanism of ringing effect caused by ideal filter (5%).
(e) the scheme for determining the direction of motion from an image degraded by uniform-linear motion blurring (5%).
 (a) Isopreference curves for a crowd and Lena's face would be different since they represent the perceived quality of an image based on human judgment. The isopreference curve for a crowd would be more focused on overall clarity and recognizability of individual objects or people, while the isopreference curve for Lena's face would place more emphasis on the fidelity of facial features. The isopreference curve for Lena's face would likely be more sensitive to distortions in the eyes, nose, and mouth regions compared to the rest of the image.

(b) The assumption for the degradation function in a degradation model is that the degradation process can be described by a mathematical function that maps a high-quality image to a degraded image. The added noise in the degradation model represents the random variations and imperfections that occur during the degradation process. The assumption is that this noise is additive and follows a certain probability distribution, such as Gaussian or uniform.

(c) The main difference between a band filter and a notch filter is the frequency range that they affect. A band filter is a type of filter that allows only a specific range of frequencies to pass through, while rejecting frequencies outside of this range. A notch filter, on the other hand, is a type of filter that rejects a specific range of frequencies, while allowing all other frequencies to pass through.
a. The isopreference curves of crowd and Lena’s face are different. The isopreference curves of crowd are more uniform, while Lena’s face has more distinct peaks. 
b. The degradation function is a monotonic increasing function and the added noise is assumed to be Gaussian distributed. 
c. The band filter is a low-pass filter which passes low frequencies and attenuates high frequencies, while the notch filter is a high-pass filter which passes high frequencies and attenuates low frequencies. 
d. The ringing effect is caused by the transition from high frequencies to low frequencies in the filtered image. 
e. The direction of motion can be determined by analyzing the gradient of the image.