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.

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

Examples

Select Region of Interest Based on Color

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

load trees
imshow(X,map)

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)

Input Arguments

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

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)

Version History

Introduced before R2006a