RandomGamma

Description

Applies random gamma correction to the input image.

    Gamma correction, or simply gamma, is a nonlinear operation used to encode and decode luminance
    or tristimulus values in imaging systems. This transform can adjust the brightness of an image
    while preserving the relative differences between darker and lighter areas, making it useful
    for simulating different lighting conditions or correcting for display characteristics.

    Args:
        gamma_limit (float | tuple[float, float]): If gamma_limit is a single float value, the range
            will be (1, gamma_limit). If it's a tuple of two floats, they will serve as
            the lower and upper bounds for gamma adjustment. Values are in terms of percentage change,
            e.g., (80, 120) means the gamma will be between 80% and 120% of the original.
            Default: (80, 120).
        eps: A small value added to the gamma to avoid division by zero or log of zero errors.
            Default: 1e-7.
        p (float): Probability of applying the transform. Default: 0.5.

    Targets:
        image

    Image types:
        uint8, float32

    Number of channels:
        Any

    Note:
        - The gamma correction is applied using the formula: output = input^gamma
        - Gamma values > 1 will make the image darker, while values < 1 will make it brighter
        - This transform is particularly useful for:
          * Simulating different lighting conditions
          * Correcting for non-linear display characteristics
          * Enhancing contrast in certain regions of the image
          * Data augmentation in computer vision tasks

    Mathematical Formulation:
        Let I be the input image and G (gamma) be the correction factor.
        The gamma correction is applied as follows:
        1. Normalize the image to [0, 1] range: I_norm = I / 255 (for uint8 images)
        2. Apply gamma correction: I_corrected = I_norm ^ (1 / G)
        3. Scale back to original range: output = I_corrected * 255 (for uint8 images)

        The actual gamma value used is calculated as:
        G = 1 + (random_value / 100), where random_value is sampled from gamma_limit range.

    Examples:
        >>> import numpy as np
        >>> import albumentations as A
        >>> image = np.random.randint(0, 256, [100, 100, 3], dtype=np.uint8)

        # Default usage
        >>> transform = A.RandomGamma(p=1.0)
        >>> augmented_image = transform(image=image)["image"]

        # Custom gamma range
        >>> transform = A.RandomGamma(gamma_limit=(50, 150), p=1.0)
        >>> augmented_image = transform(image=image)["image"]

        # Applying with other transforms
        >>> transform = A.Compose([
        ...     A.RandomGamma(gamma_limit=(80, 120), p=0.5),
        ...     A.RandomBrightnessContrast(p=0.5),
        ... ])
        >>> augmented_image = transform(image=image)["image"]

    References:
        - Gamma correction: https://en.wikipedia.org/wiki/Gamma_correction
        - Power law (Gamma) encoding: https://www.cambridgeincolour.com/tutorials/gamma-correction.htm
    

Parameters

• gamma_limit: int | tuple[int, int] | float | tuple[float, float] (default: (80, 120))
• p: float (default: 0.5)

Targets

• Image