|Image Processing Toolbox User's Guide|
Filtering a Region
Filtering a region is the process of applying a filter to a region of interest in an image, where a binary mask defines the region. For example, you can apply an intensity adjustment filter to certain regions of an image.
To filter a region in an image, use the
roifilt2 function. When you call
roifilt2, you specify an grayscale image, a binary mask, and a filter.
roifilt2 filters the input image and returns an image that consists of filtered values for pixels where the binary mask contains 1's and unfiltered values for pixels where the binary mask contains 0's. This type of operation is called masked filtering.
Example: Filtering a Region in an Image
This example uses masked filtering to increase the contrast of a specific region of an image:
BWcreated in Selecting a Polygon. The region of interest specified by the mask is the logo on the girl's jacket.
roifilt2, specifying the image to be filtered, the mask, and the filter.
Image Before and After Using an Unsharp Filter on the Region of Interest
Specifying the Filtering Operation
roifilt2 also enables you to specify your own function to operate on the region of interest. This example uses the
imadjust function to lighten parts of an image:
roifilt2, specifying the image to be filtered, the mask, and the filter. The resulting image,
I2, has the text imprinted on it.
Image Brightened Using a Binary Mask Containing Text
|Other Selection Methods||Filling a Region|
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