plot_RAW_image_distribution.py

import matplotlib.pyplot as plt
import numpy as np
import rawpy

def pack_raw(raw):
        im = raw.raw_image_visible.astype(np.float32)
        im = np.expand_dims(im, axis=2)
        img_shape = im.shape
        H = img_shape[0]
        W = img_shape[1]

        out = np.concatenate((im[0:H:2, 0:W:2, :],
                                im[0:H:2, 1:W:2, :],
                                im[1:H:2, 1:W:2, :],
                                im[1:H:2, 0:W:2, :]), axis=2)
        return out

def main(image_path):
    
    if 'arw' in image_path.lower():
        image = rawpy.imread(image_path)
        image = pack_raw(image)
    elif 'npy' in image_path.lower():
        image = np.load(image_path)

    channel_stats = []
    for channel in range(4):
        channel_values = image[:, :, channel]
        mean_value = np.mean(channel_values)
        max_value = np.max(channel_values)
        min_value = np.min(channel_values)
        channel_stats.append((mean_value, max_value, min_value))
        print(f"Channel {channel}: Mean={mean_value:.2f}, Max={max_value}, Min={min_value}")

    plt.figure(figsize=(12, 6))
    colors = ['red', 'green', (50/255, 128/255, 10/255), 'blue']

    for channel, color in zip(range(4), colors):
        plt.hist(image[:, :, channel].ravel(), bins=16353, color=color, alpha=0.7, label=f'Channel {channel}')
        
        xpos = 0.7   
        ypos = 0.88 - channel * 0.15
        plt.annotate(
            f'Mean={channel_stats[channel][0]:.2f}\nMax={channel_stats[channel][1]}\nMin={channel_stats[channel][2]}',
            xy=(xpos, ypos), xycoords='axes fraction',
            bbox=dict(boxstyle='round,pad=0.3', edgecolor=color, facecolor='lightgray'),
            fontsize=10, color=color
        )
        
    plt.title("Pixel Value Distribution for Each Channel")
    plt.xlabel("Pixel Value")
    plt.ylabel("Frequency")
    plt.legend()

    output_file = 'pixel_value_plot.png'
    plt.savefig(output_file)

if __name__=="__main__":
    # image_path = 'path/to/RAW/Image/file.ARW'
    main(image_path=image_path)