Gamma correction

Gamma correction, also referred to as gamma encoding, is an image processing technique that adjusts the brightness and contrast of an image to achieve a more natural and visually pleasing appearance.

  • Gamma correction of digital images prevents excessive storage of information about highlights that are invisible to humans and ensures sufficient information is retained for shadows that require more differentiation to be clearly observed.
  • Gamma correction adjusts the relationship between the numerical value of a pixel stored in an image file (e.g., JPG or TIFF) and its corresponding brightness when displayed on-screen.
  • Gamma correction is typically performed to compensate for the non-linear relationship between the input signal and the displayed brightness on a monitor or screen.
  • In the case of a black-and-white image, a gamma function impacts highlights (brightest values), mid-tones (greyscale), and shadows (dark areas) in distinct ways.
  • Gamma correction is not limited to black and white images but applies to colour images, where it affects colour balance and contrast.
  • The appearance of an image on a digital display is determined by the voltage associated with each pixel:
    • For instance, a computer utilized to display black-and-white images translates the numerical values of each pixel in an image file into a corresponding voltage, which is then transmitted to a monitor. The brightness of a pixel increases with higher voltages.
    • The ideal relationship between stored values and appearance is non-linear, meaning that a voltage change does not directly result in a satisfactory brightness change from an observer’s perspective.
    • For many TVs and computer displays, doubling the voltage of a specific pixel will not make it appear twice as bright. Therefore, gamma correction selectively adjusts voltages to enhance the overall appearance.
  • Gamma correction can help achieve accurate representation of images across various display devices and ensure consistent visual experiences.
  • Different applications and devices may have different default gamma settings, and users can often customize these settings based on their preferences.