Which of the following is used for the boundary representation of an image object ?
Chain codes
An object in a segmented image can be represented either by its region (the set of pixels it occupies) or by its boundary (the closed contour that encloses it). Boundary representation is preferred when shape characteristics such as perimeter and corners matter.
A chain code (Freeman chain code) represents the boundary as a starting pixel followed by a sequence of direction numbers — 0 to 3 for 4-connectivity or 0 to 7 for 8-connectivity — each giving the direction to the next boundary pixel. Following the codes traces the contour, so it is a boundary representation; its first difference makes it rotation invariant.
The other schemes describe regions: a quad tree recursively splits the image into quadrants until each block is uniform, encoding the area the object covers; run length coding stores each row of the region as runs of identical pixels; projections sum pixel values along rows or columns to give region signatures.
Chain codes option is correct.
Similar Questions
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Important Questions from Images and Graphics
- Which of the following polygon clipping algorithm can be used to clip a filled area ?
Given a simple image of size 10 × 10 whose histogram models the symbol probabilities and is given by
p1 p2 p3 p4 a b c d The first order estimate of image entropy is maximum when
A Butterworth lowpass filter of order n, with a cutoff frequency at distance D0 from the origin, has the transfer function H(u, v) given by
Given two spatial masks
\(S_1=\begin{bmatrix}0&1&0\\1&-4&1\\0&1&0\end{bmatrix}\) and \(S_2=\begin{bmatrix}1&1&1\\1&-8&1\\1&1&1\end{bmatrix}\)
The Laplacian of an image at all points (x, y) can be implemented by convolving the image with spatial mask. Which of the following can be used as the spatial mask ?
A technique used to approximate halftones without reducing spatial resolution is known as _________.
