Pyglet显示图像全黑问题求助：含OpenAI Gym场景及Numpy矩阵需求

Hey there, let's break down why you're seeing all-black outputs—this is a common gotcha with Gym's rendering module and Pyglet's image handling!

The Core Issue #

By default, gym.rendering.Image sets the anchor point at the center of the image, and its initial position is (0,0). Since your Viewer is 400x400, putting the image's center at (0,0) means the entire image sits outside the visible viewport (the viewer's coordinate system starts at (0,0) in the bottom-left corner, extending to (400,400) in the top-right). That's why you're getting nothing but black.

Fixed Code for Local Images #

Here's how to adjust your code to make the image visible:

from gym.envs.classic_control import rendering
import matplotlib.pyplot as plt

# Initialize the viewer
viewer = rendering.Viewer(400, 400)
# Load your local image
im = rendering.Image("img.png", 400, 400)

# Critical adjustments:
# 1. Set the anchor point to the bottom-left corner of the image
im.set_anchor(0, 0)
# 2. Position the image so its bottom-left corner matches the viewer's bottom-left
im.set_position(0, 0)

# Add the image to the one-time render queue
viewer.add_onetime(im)
# Render and capture the RGB array
rgb = viewer.render(return_rgb_array=True)
# Clean up the viewer to free resources
viewer.close()

# Display and save the result
plt.imshow(rgb)
plt.show()
plt.savefig("out.png")

Fix for Numpy Matrix ImageData #

If you're using a NumPy matrix with Pyglet's ImageData, you need to ensure the data format matches Pyglet's expectations, plus apply the same anchor/position fix:

from gym.envs.classic_control import rendering
from pyglet.image import ImageData
import numpy as np
import matplotlib.pyplot as plt

# Example: Create a random 400x400 RGB numpy array (uint8, 0-255 range)
rgb_matrix = np.random.randint(0, 256, size=(400, 400, 3), dtype=np.uint8)

# Convert numpy array to Pyglet ImageData
# Parameters: width, height, format, raw_data, pitch (bytes per row)
img_data = ImageData(
    width=400,
    height=400,
    format='RGB',
    data=rgb_matrix.tobytes(),
    pitch=400 * 3  # 3 bytes per pixel (RGB)
)

# Wrap in Gym's Image wrapper
im = rendering.Image(img_data, 400, 400)
# Apply the same anchor/position fix
im.set_anchor(0, 0)
im.set_position(0, 0)

# Render as before
viewer = rendering.Viewer(400, 400)
viewer.add_onetime(im)
rgb = viewer.render(return_rgb_array=True)
viewer.close()

plt.imshow(rgb)
plt.show()

Additional Checks #

• Double-check your image path: If using a relative path for img.png, make sure it's in the same directory as your script, or use an absolute path.
• Verify image format: Pyglet supports PNG, JPG, and BMP, but if your image uses RGBA instead of RGB, specify format='RGBA' when creating ImageData.
• Ensure numpy data is valid: Your matrix must be uint8 type with values between 0-255—floats or out-of-range values will cause rendering issues.

内容的提问来源于stack exchange，提问作者Jan B.