What Is a Histogram?

Histogram (Histogram), also known as mass distribution chart, is a kind of statistical report chart. The data distribution is represented by a series of vertical stripes or line segments of varying heights. Generally, the horizontal axis represents the data type, and the vertical axis represents the distribution.

In quality management, how to predict and monitor the quality of the product? How to analyze the quality fluctuation? The histogram is clear at a glance

When the shape of the histogram is normal, that is, when the process is stable at this moment, it is necessary to further compare the histogram with the specification limit (that is, the tolerance) to analyze and determine the degree to which the process meets the tolerance requirements.

The main function of histogram stretching is to expand the gray interval of an image with a small gray interval to facilitate the observation of the image. Histogram stretching is to adjust the histogram by contrast stretching, so as to "enlarge" the difference between foreground and background gray levels to achieve the purpose of enhancing contrast.

Histogram matching, also called histogram specification, refers to transforming the histogram of the original image into a histogram of a specified form or a histogram of a reference image, and then adjusting each pixel of the original image according to a known histogram. Gray value, finally get a histogram matching image. ^[4]