a horizontal bar chart that plots the brightness values of the pixels in an image. The left part of the histogram represents the shadows of an image, the middle part represents the midtones, and the right part represents the highlights. The height of the spikes indicates how many pixels there are at each brightness level. For example, a large number of pixels in the shadows (the left side of the histogram) indicates the presence of image details in the dark areas of the image. To be able to better view the lower spikes, use the slider on the right and change the vertical scale of the histogram.