Camera Histogram

Histogram of the photo can be seen at the LCD viewing panel of the DSLR. The histogram function is basically to tell us the distribution of light in the photo. It helps us to understand the ratio of dark and bright area of the photos and subsequently we can use this information to change on how we compose the photo or how we set the camera
How do we read on Histogram? Histogram basically a box with tabulated vertical bar from left to right, indicating the brightness/darkness. The brightness is sorted into 256 grey level, represented with 0 to 255. The more vertical bar that tends to the right hand side means the photo is very bright and the more it tends towards left hand side means the photo is darker. Ideally we need the histogram to be at the center so that no information is clipped to the maximum or minimum value. When the histogram reach the maximum or minimum (right/left hand most of the histogram), it means that a certain pixel is clipped with the value to 0 or 255, thus we will see either a black pixel or white pixel.

Histogram of correctly exposed image


Histogram of underexposed image


Histogram of overexposed image
 

Generally we seek for image that is correctly exposed so that all the information can be shown by the image. However, depends on situation, there are also times when we purposely want to change the exposure value to underexpose/overexpose to show the contrast or emphasize on certain objects. There are also times when the environment is very bright or dark, which will translate to more pixel clipped to the right (bright environment) and left (dark environment). Example: The histogram from a well exposed image of a seagull bird up in the sky on white clouds in background would have more pixels on the bright side and could actually look similiar to the histogram of the overexposed image above.

Histogram helps to provide us all the information of how well the photo is exposed. And with this understanding, we can change the exposure value accordingly to come out with a photo of our desired.
 

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