Color balance. This article is about the process applied to still images.
For the equivalent process applied to video, see Color grading. The left half shows the photo as it came from the digital camera. The right half shows the photo adjusted to make a gray surface neutral in the same light. In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neutral colors – correctly; hence, the general method is sometimes called gray balance, neutral balance, or white balance. Image data acquired by sensors – either film or electronic image sensors – must be transformed from the acquired values to new values that are appropriate for color reproduction or display. Generalized color balance[edit] Illuminant estimation and adaptation[edit] A seascape photograph at Clifton Beach, South Arm, Tasmania, Australia.
Where , and so that: Flash (photography) A flash is a device used in photography producing a flash of artificial light (typically 1/1000 to 1/200 of a second) at a color temperature of about 5500 K to help illuminate a scene.
A major purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the electronic flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs and flammable powders. Modern cameras often activate flash units automatically. Flash units are commonly built directly into a camera. 1909 flash-lamp 1903 view camera The earliest flashes had a quantity of flash powder consisting of a mechanical mixture of magnesium powder and potassium chlorate that was ignited by hand. Kodak Brownie Hawkeye with "Kodalite Flasholder" and Sylvania P25 blue-dot daylight-type flashbulb The all-glass AG-1 bulb was introduced in 1958.
Flash No flash. Dynamic range. Dynamic range and human perception[edit] When showing a movie or a game, a display is able to show both shadowy nighttime scenes and bright outdoor sunlit scenes, but in fact the level of light coming from the display is much the same for both types of scene (perhaps different by a factor of 10).
Knowing that the display does not have a huge dynamic range, the program makers do not attempt to make the nighttime scenes millions of times less bright than the daytime scenes, but instead use other cues to suggest night or day. A nighttime scene will usually contain duller colours and will often be lit with blue lighting, which reflects the way that the human eye sees colours at low light levels.
Examples of usage[edit] Audio[edit] Audio engineers often use dynamic range to describe the ratio of the amplitude of the loudest possible undistorted sine wave to the root mean square (rms) noise amplitude, say of a microphone or loudspeaker. Electronics[edit] Electronics engineers apply the term to: Glare (vision) Glare is difficulty seeing in the presence of bright light such as direct or reflected sunlight or artificial light such as car headlamps at night.
Because of this, some cars include mirrors with automatic anti-glare functions. Glare is caused by a significant ratio of luminance between the task (that which is being looked at) and the glare source. Factors such as the angle between the task and the glare source and eye adaptation have significant impacts on the experience of glare. Glare can be generally divided into two types, discomfort glare and disability glare.
Discomfort glare results in an instinctive desire to look away from a bright light source or difficulty in seeing a task. Example of a situation where glare can be problematic, if, for instance, the ability to determine the distance and speed of passing cars is reduced. Glare can reduce visibility by: Light field measurements can be taken to reduce glare with digital post-processing. where is the common logarithm,