ROI-Based Processing
Define and operate on regions of interest (ROI)
A region of interest (ROI) is a portion of an image that you want to filter or operate on in some way. You can represent an ROI as a binary mask image. In the mask image, pixels that belong to the ROI are set to1
and pixels outside the ROI are set to0
. The toolbox offers several options to specify ROIs and create binary masks.
The toolbox supports a set of objects that you can use to create ROIs of many shapes, such circles, ellipses, polygons, rectangles, and hand-drawn shapes. After you create the objects, you can modify their shape, position, appearance, and behavior. For more information about the ROI shapes, seeCreate ROI Shapes.
Functions
Topics
Specify ROIs
- Specify ROI as Binary Mask
You can create a binary mask by selecting pixels based on intensity values or position, or by using binary segmentation techniques. - Create ROI Shapes
ROI objects represent ROIs as geometric and hand-drawn shapes. - Create Binary Mask Using an ROI Function
This example shows to create a binary mask using one of the ROI creation functions, such asdrawcircle
, with the mask creation functioncreateMask
. - Classify Pixels That Are Partially Enclosed by ROI
Learn how many Image Processing Toolbox™ functions classify pixels that are only partially within the boundaries of a region of interest.
Filter ROIs
- Overview of ROI Filtering
To filter a region of interest (ROI), first define a mask to separate the ROI from the background, then apply the filter to the ROI only. - Sharpen Region of Interest in an Image
This example shows how to use masked filtering to increase the sharpness of a specific region of interest. - Apply Custom Filter to Region of Interest in Image
This example shows how to define your own function and mask to filter a region of interest. - Fill Region of Interest in an Image
The process of filling a region of interest involves replacing all pixels in the region by interpolating inward from the boundary of the region.
Create Interactive ROIs Using Events and Callback Functions
- Subsample or Simplify a Freehand ROI
This example shows how to subsample or reduce the number of points in aFreehand
ROI object. - 使用矩形旋转图像交互ROI
This example shows how to rotate an image by using a Rectangle ROI with a callback function that callsimrotate
when you move the ROI. - Use Polyline to Create Angle Measurement Tool
This example shows how to create an interactive tool that displays the angle between three vertices in a polyline ROI. - Measure Distances in an Image
This example shows how to use line ROIs to measure distances in an image. - Use Wait Function After Drawing ROI
This example shows how to define a custom wait function that blocks the MATLAB® command line until you finish positioning a rectangle.