How to apply a Color Thresholder function in Image Batch Processor to get masked RGB Images instead of binary ones?

Hi

I've used color thresholder to create a function that extracts certain objects from an image and set background to black. This is the generated function:

function [BW,maskedRGBImage] = createMask(RGB)

%createMask Threshold RGB image using auto-generated code from colorThresholder app.

% [BW,MASKEDRGBIMAGE] = createMask(RGB) thresholds image RGB using

% auto-generated code from the colorThresholder app. The colorspace and

% range for each channel of the colorspace were set within the app. The

% segmentation mask is returned in BW, and a composite of the mask and

% original RGB images is returned in maskedRGBImage.

% Auto-generated by colorThresholder app on 07-Oct-2021

%------------------------------------------------------

% Convert RGB image to chosen color space

I = RGB;

% Define thresholds for channel 1 based on histogram settings

channel1Min = 23.000;

channel1Max = 80.000;

% Define thresholds for channel 2 based on histogram settings

channel2Min = 33.000;

channel2Max = 84.000;

% Define thresholds for channel 3 based on histogram settings

channel3Min = 0.000;

channel3Max = 34.000;

% 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;

end

However, when I apply this function for a batch of images in Image batch processor, I'm only getting the binary masks (the selected objects are white and a black background) as outputs.

Can you tell me how to get the objects in my image batch as RGB with black background?

Thanks

Answer 1

[Image Analyst]

You need to call it in a loop over all your images, like

folder = pwd; % Whatever.
filePattern = fullfile(folder, '*.png');
fileList = dir(filePattern);
for k = 1 : numImages
    % Read in original image
    thisFileName = fullfile(fileList(k).folder, fileList(k).name);
    fprintf('Reading "%s".\n', thisFileName);
    rgbImage = imread(thisFileName);
    % Do color segmentation.
    [mask, maskedRGBImage] = createMask(rgbImage);
    % Now display the three images
    subplot(2, 2, 1);
    imshow(rgbImage)
    subplot(2, 2, 2);
    imshow(mask);
    subplot(2, 2, 3);
    imshow(maskedRGBImage);
    drawnow;
end

Or if you're using the batch processing app, maybe it's using only the first output. Try reversing the outputs:

function [maskedRGBImage, BW] = createMask(RGB)

[Michael Aboud]

Reversing the outputs did the trick, thank you so much