How to generate mask R-CNN training set data from matlab's image labeler

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I use Image labeler to mark images, Rectangle to mark object positions and Pixel to mark object categories. However, the generated gTruth file cannot be directly used for mask R CNN training, nor can it directly use the imageDatastore and boxLabelDatastore instructions to directly generate relevant data.
I followed the instructions on matlab's web page and used imageDatastore to grab the RGM image path from gTruth.
imageFilesA = gTruth.DataSource.Source;
imds = imageDatastore(imageFilesA);
Reorganize object position label data and use boxLabelDatastore to generate boxes and labels data.
rawBoxes = gTruth.LabelData{:, 1};
allBoxes = cell(size(rawBoxes,2));
for i = 1:numel(rawBoxes)
boxes = rawBoxes{i};
numBoxes = size(boxes, 1);
allBoxes{i,2} = string(repmat({'WWL'}, numBoxes, 1));
end
allBoxes = cell2table(allBoxes,'VariableNames',{'Boxes','Labels'});
blds = boxLabelDatastore(allBoxes);
But the final masks data cannot be generated. Because when I use imageDatastore to generate mask image file path data, I follow the instructions to generate H*W*M data (where H*W is the image size and M is the number of objects in the image).
Assuming that the first image has 4 markers and I generate a 1*4 cell image file path, an error will occur when using imageDatastore. If I store four image file paths into a 1*4 table, imageDatastore can be used, but when I need to combine three data later, a parameter error will be displayed.
Here is one of the methods I tried
maskPaths = gTruth.LabelData{:, 2};
numImages = numel(maskPaths);
logicalMasks = cell(numImages, 1);
tempdir='F:\MaskRCNN\ImageIMDS\';
targetMaskPaths = {};
for i = 1:numImages
mask = imread(maskPaths{i});
[H, W] = size(mask);
boxes = rawBoxes{i};
M = size(boxes, 1);
for j = 1:M
logicalMask = mask;
tempMaskFilePath = fullfile(tempdir, sprintf('mask_%d_target_%d.png', i, j));
imwrite(uint8(logicalMask), tempMaskFilePath);
targetMaskPaths{i,j} = tempMaskFilePath;
end
end
classes = ["WL"];
labelIDs = [0 1];
pxds = imageDatastore(targetMaskPaths);
Error message
Error using matlab.io.datastore.ImageDatastore (line 305)
Files must be a valid string scalar, character vector, cell array of character vectors,
string array, or a matlab.io.datastore.FileSet.
Error in imageDatastore (line 139)
ds = matlab.io.datastore.ImageDatastore(location, varargin{:});
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error in MaskTest (line 77)
pxds = imageDatastore(targetMaskPaths);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Here is one of the methods I tried
maskPaths = gTruth.LabelData{:, 2};
numImages = numel(maskPaths);
logicalMasks = cell(numImages, 1);
tempdir='F:\MaskRCNN\ImageIMDS\';
targetMaskPaths = {};
for i = 1:numImages
mask = imread(maskPaths{i});
[H, W] = size(mask);
boxes = rawBoxes{i};
M = size(boxes, 1);
targetMaskPaths = cell(M, 1);
for j = 1:M
logicalMask = mask;
tempMaskFilePath = fullfile(tempdir, sprintf('mask_%d_target_%d.png', i, j));
imwrite(uint8(logicalMask), tempMaskFilePath);
targetMaskPaths{i,j} = tempMaskFilePath;
end
logicalMasks{i} = targetMaskPaths';
end
classes = ["WL"];
labelIDs = [0 1];
pxds = imageDatastore(targetMaskPaths);
Error message
Error using trainMaskRCNN (line 181)
[trainedNet] = trainMaskRCNN(trainingData, net, options);
^^^^^^^^^^^^
Invalid argument at position 1. Expected input to be one of these types:
logical
Instead its type was uint8.
Error in MaskTest (line 99)
[trainedNet] = trainMaskRCNN(trainingData, net, options);

Answers (1)

Gayathri
Gayathri on 28 Oct 2024
I understand that you are facing an error while creating the ImageDatastore” object of the tempMaskFilePath in the first approach mentioned.
This is because ImageDatastore” function expects the input to be a valid string scalar, character vector, cell array of character vectors / string arrays or a matlab.io.datastore.FileSet”.
I created a sample code snippet to replicate the issue. To resolve this, we can make the “targetMaskPaths” variable to a one-dimensional array of string arrays using the line of code shown below.
targetMaskPaths{end+1} = tempMaskFilePath;
With this code we can obtain a structure for “pxds” variable as shown below.
For more information on “ImageDatastore” function please refer to the following link.
And for more information on Mask R-CNN, please refer to the below link.
Hope you find this information helpful.

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