Understanding histograms photography
What is a histogram? The histogram in photography is a simple bar chart showing the distribution of pixels in an image, based on brightness.
Histogram inform the photographer about the level of accuracy obtained light after taking a picture. This is very important manner because each DSLR's has a different basic pixel on LCD screen behind the camera.
While you look at the picture shortly after taking the picture, you might think that the level of accuracy is light enough, but when viewed through a histogram, it could be the image you produced is in the category of under-exposure or vice versa.
There are three categories that you can use as a guide to see the histogram.
The first category is Under exposure
Under exposure means the images that you produced have a darker light levels from the normal light when you take that picture.
To determine the value of these under exposure, you can see the peaks in the histogram. If the peaks produced by are drawing more on the left, the image is in category of under exposure.
The second category is Normal exposure
Normal exposure means the images that you produced have a perfect light level according to the light when you take that picture. To determine the value of normal exposure, you can see the peaks on the histogram are mostly place in the middle.This is the match exposure on your images.
The third category is Over exposure
Over exposure means the images that you produced have a lighter light level from the normal light when you take that picture.
This means that lots of the pixels are too bright for the camera’s sensor and have burned out to pure white. To determine this over exposure is by viewing your histogram peaks are mostly place in the right hand position.
There is no such thing as a perfect histogram. You can only judge it to see if the graph looks how you’d expect it to and adjust the exposure to correct it if things don’t tally up.
For an average image with no strong highlights or shadows, you can expect to see a peak in the graph in the middle, showing an average distribution of tones.
With a darker image, such as a lowlight scene, you can expect to see a peak to the left. A peak to the right would denote a high-key image.
From the picture above we can see the left hand side represents the darkest pixels, the middle corresponds to the midtones and the right-hand side the white pixels. Just try and shoot an images in a few range exposure and see how its compare to each other exposure.