# Performing Blob Analysis

Use a Blob tool to examine a region of an image and locate features that are composed of pixels within a limited range of grey values and whose shape is often unpredictable. Vision applications use blob analysis to provide information about the presence, number, location, shape, and orientation of certain features within an image. You can also use blob analysis to discover how features in an image relate to one another topologically.

Term | Definition
--- | ---
morphology | Process of altering the shapes of regions by applying arithmetic operators to neighborhoods of pixels within an image.
relative thresholding | Defining a threshold value relative to the distribution of pixel values within an image.
run-length encoding (RLE) | Data-compression technique that compresses runs of bytes with the same value by storing them as a run length and a value.
second moment of inertia | Tendency of a stationary body to resist rotation about an axis. The moment of inertia of an object about a particular axis is computed by multiplying the mass of each part of the object times the square of the distance of that part from the given axis.
segmentation | Division of image pixels into object pixels and background pixels. Segmentation is an essential part of blob analysis.
thresholding | Segmentation performed by picking a simple threshold value; pixels on one side of the threshold are object pixels, those on the other side are background pixels. Also called absolute thresholding.
topology | Method of describing the spatial relationships between regions.