MATLAB: How to find only leaves in a gray scale image acquired using IR camera for Thermal imaging

computer visionComputer Vision Toolboximage analysisimage processingImage Processing Toolboximage segmentationthermal

I get only a gray scale image like this from IR camera and I need to write a code that would detect ONLY LEAVES from each plant.

I have no idea what sort of algorithms should I go for in order to that because of complex background. Any suggestions on what I should look for would be greatly appreciated.

Best Answer

You could use image analysis. If the leaves are a temperature different than the rest of the scene, simply threshold and call regionprops().

See my Image Segmentation Tutorial for a full demo. http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

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MATLAB: How to remove complex background on a grayscale Image and do Object Detection.

You should attach the image. All I can say now is to use a better background if possible, and use a color camera or a monochrome camera with a filter that can improve the contrast between the subject (green plants) and the background.

MATLAB: How to detect skin region in YCbCr color space

Hi,

You can use ‘Color Thresholder’ app provided in the Image Acquisition Toolbox.

After loading the image from a file/workspace, you can choose a color space for the image. Since you want to extract purple and yellow colours, I would recommend you to use YCbCr for purple colour and RGB space for the yellow colour.
You would then see the image along with a set of controls for each colour component, depending on the colour space chosen. Adjust these controls to get the colour you want. And ‘Export Function’ for the resultant image.
By exporting to function, you get Min and Max values for each channel for both the colours (yellow and Purple). You would also get a sliderBW matrix in each function. Use logical operator || to include both the matrices in your workspace and then set these pixels to white colour.

You can also refer to an example for purple colour from the documentation provided in the link.

Below is the code for an image file named ‘peppers.png’ and may need to be changed in some cases -

% Load your image in RGB variable 
% Convert RGB image to chosen color space 
I = RGB; 
  
% Define thresholds for channel 1 based on histogram settings 
channel1Min = 53.000; 
channel1Max = 178.000; 
  
% Define thresholds for channel 2 based on histogram settings 
channel2Min = 55.000; 
channel2Max = 153.000; 
  
% Define thresholds for channel 3 based on histogram settings 
channel3Min = 37.000; 
channel3Max = 142.000; 
  
% Create mask based on chosen histogram thresholds 
sliderBW = (I(:,:,1) >= channel1Min ) & (I(:,:,1) <= channel1Max) & ... 
    (I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ... 
    (I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max); 
BW = sliderBW; 
  
% Initialize output masked image based on input image. 
maskedRGBImage = RGB; 
  
% Set background pixels where BW is false to zero. 
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;

Best Answer

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MATLAB: How to detect skin region in YCbCr color space

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