What is the effect of convolution with the following mask? $$\frac19 \pmatrix{1 & 1 & 1\cr 1 & 1 & 1\cr 1 & 1 & 1\cr}$$
it will blur edges
If a histogram has two visible peaks, where is the best place to set a threshold to isolate the corresponding regions?
mid-way between the peaks
How does the time taken to perform a convolution vary with the dimension of a (square) mask?
it is proportional to the square of the dimension of the mask
Why is simple thresholding not especially effective at locating light features in an image?
changes in illumination change the lightness of features
What is the effect of convolving an image with the mask $$\pmatrix{0 & 1 & 0\cr 0 & 0 & 0\cr 0 & 0 & 0\cr}$$
the image is shifted down one pixel
The Laplacean mask is useful for:
locating isolated white pixels
The correlation coefficient between two images is a quantity that lies in the range -1 to +1. What does a value of -1 represent?
one of the images is like a photographic negative of the other
What is the effect of convolving an image with a +-shaped mask?
+-shaped features will be enhanced
What is the effect of convolving an image with the mask $$\pmatrix{0 & 1 & 0\cr 1 & 1 & 1\cr 0 & 1 & 0\cr}$$
+-shaped features will be enhanced
What is the effect of convolving an image with the mask $$\pmatrix{0 & 1 & 0\cr 1 & -4 & 1\cr 0 & 1 & 0\cr}$$
dark spots will be enhanced