roicolor

Select region of interest (ROI) based on color

Syntax

BW = roicolor(I,low,high)

BW = roicolor(I,v)

Description

BW = roicolor(I,low,high) returns an ROI selected as those pixels in image I that lie within the range [low high]. The returned value, BW, is a binary image with 0s outside the region of interest and 1s inside.

example

BW = roicolor(I,v) returns an ROI selected as those pixels in image I that match values in vector v.

Examples

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Select Region of Interest Based on Color

Open Live Script

Load an indexed image X with colormap map. The colormap has 128 colors. Display the indexed image.

load trees
imshow(X,map)

Figure contains an axes object. The hidden axes object contains an object of type image.

Create a binary mask image based on color. The mask is true for pixels with index in the range [10, 20]. The mask is false for pixels with index outside this range.

BW = roicolor(X,10,20);

Display the binary mask.

imshow(BW)

Figure contains an axes object. The hidden axes object contains an object of type image.

Input Arguments

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`I` — Indexed or grayscale image
m-by-n numeric matrix

Indexed or grayscale image, specified as an m-by-n numeric matrix.

`low` — Minimum value
numeric scalar

Minimum value to include in the ROI, specified as a numeric scalar.

`high` — Maximum value
numeric scalar

Minimum value to include in the ROI, specified as a numeric scalar.

`v` — Set of values
numeric vector

Set of values to include in the ROI, specified as a numeric vector.

Output Arguments

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`BW` — Binary image
m-by-n logical matrix

Binary image, returned as an m-by-n logical matrix.

Data Types: logical

Tips

You can use the returned image as a mask for masked filtering using roifilt2.
If you specify a colormap range, [low high], then
```
BW = (I >= low) & (I <= high)
```
If you specify a set of colormap values, v, then the mask generated by roicolor is equivalent to:
```
BW = ismember(I,v)
```