Thresholding Tool

Interactively select intensity level for image thresholding.

Description

THRESH_TOOL launches a GUI (graphical user interface) for thresholding an intensity input image, IM. IM is displayed in the top left corner. A colorbar and IM's histogram are displayed on the bottom. A line on the histogram indicates the current threshold level. A binary image is displayed in the top right based on the selected level. To change the level, click and drag the line. The output image updates automatically.

There are two ways to use this tool.
 
Mode 1 - nonblocking behavior:
THRESH_TOOL(IM) launches GUI tool. You can continue using the MATLAB Desktop.Since no results are needed, the function does not block execution of other commands.
 
THRESH_TOOL(IM,CMAP) allows the user to specify the colormap, CMAP. If not specified, the default colormap is used.
 
THRESH_TOOL(IM,CMAP,DEFAULTLEVEL) allows the user to specify the default threshold level. If not specified, DEFAULTLEVEL is determined by GRAYTHRESH. Valid values for DEFAULTLEVEL must be consistent with the data type of IM for integer intensity images: uint8 [0,255], uint16 [0,65535], int16 [-32768,32767].
 
Example
x = imread('rice.png');
thresh_tool(x)
%no return value, so MATLAB keeps running
 
Mode 2 - blocking behavior:
LEVEL = THRESH_TOOL(...) returns the user selected level, LEVEL, and MATLAB waits for the result before proceeding. This blocking behavior mode allows the tool to be inserted into an image processing algorithm to support an automated workflow.
 
[LEVEL,BW] = THRESH_TOOL(...) also returns the thresholded binary output image, BW.

Example
x = imread('rice.png');
lev = thresh_tool(x) %MATLAB waits for GUI tool to finish
 
See also colormap, graythresh, im2bw.

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
hline and vline

• Required Products: Image Processing Toolbox
• MATLAB release: MATLAB 7 (R14)
• Other Files: license.txt, ; thresh_tool.m

[ivan scardanzan]

X=imread('abc.jpg');
>> thresh_tool(X);
??? Assignment has more non-singleton rhs dimensions than non-singleton
subscripts.

Error in ==> ind2rgb at 35
  rout(:,:,1) = r;

Error in ==> subimage>parse_inputs at 150
        cdata = im2uint8(ind2rgb(varargin{1},varargin{2}));

Error in ==> subimage at 43
[x,y,cdata] = parse_inputs(varargin{:});

Error in ==> thresh_tool at 49
subimage(im,full_map)

>> X=X(:,:,1);
>> thresh_tool(X);

[Carlos Oliveira]

Very useful tool.

[piyush jain]

 

[Sudip Ghosh]

This is an excellent tool! Thanks!

[M Rosenbluth]

Nice gui.

[Naveen Kumar]

x= imread('a.jpg');
 lev = thresh_tool(x,[1.0 1.0 0])

??? Assignment has more non-singleton rhs dimensions than non-singleton
subscripts.

Error in ==> ind2rgb at 35
  rout(:,:,1) = r;

Error in ==> thresh_tool>im2rgb at 118
    rgb = ind2rgb(ind,full_map);

Error in ==> thresh_tool at 110
rgb = im2rgb(im,full_map);

**WHAT SHOULD B DONE TO RESOLVE THIS PROBLEM**

[veysel gökhan böcekçi]

 

[Benjamin Benson]

Neat tool and nice gui. For all guys having problems with assignment error: You should load a grayscale image:
x = rgb2gray(imread('img.png'));

[Nathan Tomlin]

didn't work for me - I got the same errors as listed above

[Nathan Tomlin]

I apologize for cluttering the comments - didn't read carefully (and wish I could edit previous posts...). Like Benjamin said, it doesn't work if you input an RGB image. Just add:

if ndims(im) == 3
im = rgb2gray(im);
end
thresh_tool(im)

[Robert Bemis]

Nathan and others, thanks for all the feedback. Some users have been tripped up by the requirement that the input must be an intensity image. RGB color is not supported. I will update the function to for this at the beginning and stop immediately with a more helpful error message.

[Charles Griffin]

I'm just beginning to learn image segmentation for a Masters thesis. My thesis is on remote sensing and I was told that thresholding was the way to go on this thesis. Do you have any suggestions that could narrow my research in a more directed path?

[pkenned Kennedy]

Hi Robert, thank you for this program, it is most helpful. I have a slight problem however, when I import a 16 bit dicom file the input image on the left appears with the jet colormap. I changed line 103 to gray but now I just get a black image. Do i need to edit dislayrange somehow?