imneonizer / How-to-find-if-an-image-is-bright-or-dark

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 a threshold value.

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.

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