SpyderX Monitor Calibration Library

This project provides Python classes to interface with a SpyderX Pro colorimeter for measuring and calibrating monitor gamma. It combines PyUSB for USB communication and PsychoPy for precise visual presentation of gray levels.

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Project Structure

The project includes the following files:

1. cal_lib.py:

   • Contains the SpyderX class for communicating with the SpyderX device.
   • Includes GammaFitter to fit gamma curves using luminance measurements.

2. cal_psy.py:

   • Contains the GrayLevels class for measuring luminance and fitting gamma curves using PsychoPy.
   • Displays gray levels and measures luminance to calibrate monitor gamma.

3. Example Usage:

   • In Demo.py file you can find a demonstration on how to use the code

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Dependencies

Ensure the following libraries are installed:

• PyUSB for USB communication:

  pip install pyusb
  

• PsychoPy for visual stimulus presentation:

  pip install psychopy
  

• NumPy and SciPy for numerical computations:

  pip install numpy scipy
  

• Matplotlib for plotting gamma curves:

  pip install matplotlib
  

Installing libusb on Windows

IMPORTANT: This step requires visual studio with several components installed.

1. Clone and bootstrap vcpkg:

   git clone https://github.com/microsoft/vcpkg.git
   cd vcpkg
   bootstrap-vcpkg.bat
   

2. Install libusb:

   vcpkg install libusb

3. Find libusb-1.0.dll in:

   vcpkg\installed\x64-windows\bin\libusb-1.0.dll

How to Use

Basic Usage

Here is a demo script that performs monitor calibration:

from cal_lib import SpyderX
from cal_psy import GrayLevels
import numpy as np

# Path to the libusb-1.0.dll file
libusb_path = r"C:\path\to\libusb-1.0.dll"

# Initialize the SpyderX device
spyder = SpyderX(libusb_path)

# Initialize the GrayLevels class
gl = GrayLevels(spyder, fullscr=True)

# Perform black-level calibration
gl.calibrate()

# Measure gray levels and fit gamma
gammas = []
gfit = gl.measure(num_levels=12)
gammas.append(gfit.gamma)

# Repeat measurements for better accuracy
for i in range(3):
    gfit = gl.measure(num_levels=12, wait_user=False)
    gammas.append(gfit.gamma)

print(f"Average Gamma Value: {np.mean(gammas):.3f}")

# Clean up
gl.close()

Steps to Calibrate Your Monitor

1. Install the libusb driver as described above.

2. Connect the SpyderX device to your computer.

3. Change the default driver to libusbK using Zadig

4. Run the script:

   • Perform black calibration by covering the SpyderX sensor.
   • Place the SpyderX on the monitor as instructed.
   • Measure luminance values for a range of gray levels.

5. Analyze the Gamma Curve:

   • The script will fit a gamma curve and compute the gamma value.
   • The curve will be displayed using matplotlib.

6. Average Multiple Measurements:

   • For better results, repeat the measurement process.

Tips for Better Calibration

1. Run in Full-Screen Mode:

   • Use fullscr=True when initializing the GrayLevels class to ensure precise display of gray levels.

2. Stabilize the Display:

   • Allow a brief pause (e.g., pause=1 second) after each gray level display to ensure the monitor luminance stabilizes.

3. Cover the SpyderX for Black Calibration:

   • Ensure the SpyderX sensor is covered during black calibration for accurate measurements.

4. Avoid Ambient Light:

   • Perform calibration in a dark room to minimize interference from ambient light.

5. Repeat Measurements:

   • Repeating measurements multiple times and averaging the gamma value improves accuracy.

Troubleshooting

• If the system installs DataColor Driver remove them completely using RAPR
• Then install libusbK using Zadig

Credits

• The SpyderX class was adapted from the work (for macOS) of patrickmineault.