How to find if an image is bright or dark?

Concept

• Input image is resized to 10x10 pixel, to reduce the computation.
• Convert it to LAB color space to access the luminous channel which is independent of colors.
• Normalize pixel values to be in range of 0 - 1.
• Compare the mean value of pixels with an threshold value.

External modules

>> pip install opencv-python
>> pip install numpy

How to run

• Demo: Colab Notebook

• Execute program

  python run.py
  

  • It will read images from images directory and classify it as bright or dark.
  • It will separate and save images to output/bright directory and output/dark directory accordingly.

• Sample Dark Images

  

• Sample Bright Images

  

• The function calculate brightness level in range of 0-1, hence you can decide on a threshold to treat images either as bright or dark.

  def isbright(image, dim=10, thresh=0.5):
      # Resize image to 10x10
      image = cv2.resize(image, (dim, dim))
      # Convert color space to LAB format and extract L channel
      L, A, B = cv2.split(cv2.cvtColor(image, cv2.COLOR_BGR2LAB))
      # Normalize L channel by dividing all pixel values with maximum pixel value
      L = L/np.max(L)
      # Return True if mean is greater than thresh else False
      return np.mean(L) > thresh
  

• For a better result you can tweak with dim parameter, it will preserve more pixels while calculating brightness levels.

• Don't forget to star the repository.