An image histogram is a vital tool for
assessing the light and color in an image, yet itís not widely used or
understood by many people yielding a camera. Understanding the histogram will
not only help while taking photos, but also with post-processing.
Image histograms are present on many modern digital
and DSLR cameras. Photographers can use them as an aid to show the distribution of tones captured, and whether image detail has been lost to blown-out highlights or blacked-out shadows.
Histogram of Sunflower image
The horizontal axis of the graph represents the tonal variations, while the vertical axis represents the number of pixels in that particular tone. The left side of the horizontal axis represents the black and dark areas, the middle represents medium grey and the right hand side represents light and pure white areas. The vertical axis, on the other hand, represents the size of the area which is captured in each one of these zones.
Image manipulation and histograms
Image editors typically have provisions to create a histogram of the image being edited. The histogram plots the number of pixels in the image (vertical axis) with a particular brightness
value (horizontal axis). Algorithms in the digital editor allow the user to visually adjust the brightness value of each pixel and to dynamically display the results as adjustments are made. Improvements in picture brightness and contrast can As a result be obtained.
Color histogram, a multidimensional histogram of the distribution of color in an image