Visualizing the PASCALRAW nef format image with OpenCV and rawpy

visualize_PASCALRAW_nef.py

import cv2
import imageio
import rawpy

class RawImage:
    """
    A class for working with raw image files.

    Attributes:
        file_path (str): The path to the raw image file.
        raw: The rawpy object representing the raw image.
    """

    def __init__(self, file_path):
        """
        Initializes a RawImage object.

        Args:
            file_path (str): The path to the raw image file.
        """
        self.file_path = file_path.lower()
        self.raw = None
        
    def load_raw_image(self):
        """
        Loads the raw image from the file.
        """
        self.raw = rawpy.imread(self.file_path) if "nef" in self.file_path else imageio.v2.imread(self.file_path)

    def get_rgb_image(self):
        """
        Returns an RGB image from the raw image, after applying color transformation matrix.

        Returns:
            numpy.ndarray: The RGB image.
        """
        rgb = self.raw.postprocess(use_camera_wb=False, gamma=(2.2, 2.2), no_auto_bright=False, output_bps=16, half_size=False)
        return cv2.cvtColor(rgb, cv2.COLOR_BGR2RGB)
    
    def show_resized_image(self, window_size=(600, 400)):
        """
        Shows a resized version of the RGB image in a window.

        Args:
            window_size (tuple, optional): The desired size of the window. Defaults to (600, 400).
        """
        rgb = self.get_rgb_image()
        h, w = rgb.shape[:2]

        # Calculate the scaling factor to fit the image into the window
        scaling_factor = min(window_size[0] / w, window_size[1] / h)

        # Calculate the new dimensions of the image after scaling
        new_size = (int(w * scaling_factor), int(h * scaling_factor))

        # Resize the image to fit the window
        resized_img = cv2.resize(rgb, new_size)

        # Create a window with the desired size
        cv2.namedWindow('Image', cv2.WINDOW_NORMAL)
        cv2.resizeWindow('Image', window_size)

        # Show the resized image in the window
        cv2.imshow('Image', resized_img)
        cv2.waitKey(0)
        cv2.destroyAllWindows()

if __name__ == "__main__":
    file_path = "2014_000001.nef"
    raw_image = RawImage(file_path)
    raw_image.load_raw_image()
    raw_image.show_resized_image()