DIP-quiz-3

DIP_quiz_3 - Image segmentation

Q1 Thresholding

• Factors affecting thresholding
  • Noise $\rightarrow$ Distribution of image, hard to execute thresholding process
  • foreground ratio $\rightarrow$ Distribution of image, hard to execute thresholding process
  • The uniformity of the illumination source $\rightarrow$ Distribution of image, hard to execute thresholding process
• Otsu’s method
  • 唯一需要注意的点在于，新的m1与m2的计算，是需要重新计算组内的概率分布!!! 即$P_1*m_1 + P_2*m_2 = m_G$, 而不是$m_1 + m_2 = m_G$!!!

Q2 Image transforms

• Direct component of Hadamard transformation is concentrated on the upper left first pixel
• Haar wavelet transform

Q3 Chain code

• Boundary following

Q4 Hough transform

• List equations, substitute points, find intersections