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import cv2
import numpy as np
class DICOM_Utils(object):
def apply_windowing(image_array, window_center, window_width):
"""
Apply windowing to a DICOM image array.
Parameters:
- image_array: numpy array of the DICOM image
- window_center: center of the window
- window_width: width of the window
Returns:
- Windowed image array
"""
lower_bound = window_center - (window_width / 2)
upper_bound = window_center + (window_width / 2)
# Apply windowing
windowed_image = image_array.copy()
windowed_image[windowed_image < lower_bound] = lower_bound
windowed_image[windowed_image > upper_bound] = upper_bound
# Normalize to [0, 255]
windowed_image = ((windowed_image - lower_bound) / window_width) * 255
return windowed_image.astype('uint8')
def apply_CAM_overlay(heatmap, windowed_image, overlay_alpha=0.4):
"""
Apply CAM (Class Activation Map) overlay to a given image.
Parameters:
- heatmap: torch.Tensor, the heatmap generated by CAM.
- windowed_image: numpy.ndarray, the windowed image to overlay the heatmap on.
- overlay_alpha: float, the transparency for overlaying heatmap. Default is 0.4.
Returns:
- overlayed: numpy.ndarray, the resulting image after overlaying the heatmap.
"""
# Convert the heatmap tensor to a numpy array
heatmap_np = heatmap.cpu().numpy().squeeze()
# Normalize the heatmap to [0, 255]
heatmap_normalized = ((heatmap_np - heatmap_np.min()) /
(heatmap_np.max() - heatmap_np.min()) * 255).astype(np.uint8)
# Convert the normalized heatmap to a colormap (for example, using the "jet" colormap)
heatmap_colormap = cv2.applyColorMap(heatmap_normalized, cv2.COLORMAP_JET)
# Resize the colormap to the original image size
heatmap_resized = cv2.resize(heatmap_colormap,
(windowed_image.shape[1], windowed_image.shape[0]))
# Convert the grayscale windowed_image to 3 channels
windowed_image_colored = cv2.cvtColor(windowed_image, cv2.COLOR_GRAY2BGR)
# Overlay the heatmap on the original image with a certain transparency
overlayed = cv2.addWeighted(windowed_image_colored, 1 - overlay_alpha,
heatmap_resized, overlay_alpha, 0)
return overlayed
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