Converting Detectron2 instance segmentation to opencv Mat array

I am trying to get a binary image from the instance segmentation output performed using Detectron2. According to the official documentation the mask’s output format is the following:

“pred_masks”: a Tensor of shape (N, H, W), masks for each detected instance.

So i tried converting it to numpy: mask = outputs["instances"].get("pred_masks").numpy() The output was the following:

[[[False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]]

 [[False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  ...
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]]

 [[False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  ...
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]]

 ...

 [[False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  ...
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]]

 [[False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  ...
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]]

 [[False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]
  ...
  [False False False ... False False False]
  [False False False ... False False False]
  [False False False ... False False False]]]

However the data type was boolean so i added the following line to get closer to the opencv format: array = (mask > 126) * 255

[[[0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  ...
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]]

 [[0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  ...
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]]

 [[0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  ...
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]]

 ...

 [[0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  ...
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]]

 [[0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  ...
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]]

 [[0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  ...
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]
  [0 0 0 ... 0 0 0]]]

And that is as far as I went to. I would like to be able to visualize each mask individually as an opencv image: cv2.imshow("Mask", mask) , without having to save the image.

What I would like to achieve

Thank you in advance.

Answer

I hope this will give a solution for what you expecting

mask_array = outputs['instances'].pred_masks.numpy()
num_instances = mask_array.shape[0]
mask_array = np.moveaxis(mask_array, 0, -1)
mask_array_instance = []
output = np.zeros_like(im) #black
#print('output',output)
for i in range(num_instances):
    mask_array_instance.append(mask_array[:, :, i:(i+1)])
    output = np.where(mask_array_instance[i] == True, 255, output)
cv2.imwrite(mask_path+'/'+item+'.jpg',output)#mask

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Answer