OpenCV で読み込まれた画像が Matplotlib で不正確な色を表示するのはなぜですか?

<code class="python">RGB_img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)</code>

<code class="python">import cv2
import matplotlib.pyplot as plt

# Load image with BGR order (default for OpenCV)
img = cv2.imread('lena_caption.png', cv2.IMREAD_COLOR)

# Convert BGR to RGB for compatibility with Matplotlib
RGB_img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

# Create grayscale image
bw_img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

# Create figure for plotting
fig, axes = plt.subplots(1, 2)

# Plot original image with corrected color order
axes[0].imshow(RGB_img)
axes[0].set_title('Original Image (RGB)')
axes[0].set_xticks([]); axes[0].set_yticks([])

# Plot grayscale image
axes[1].imshow(bw_img, cmap='gray')
axes[1].set_title('BW Image')
axes[1].set_xticks([]); axes[1].set_yticks([])

plt.show()</code>