Hi,
Histograms are a way of visualizing the predominant intensities of an image, not the highest intensity region. As a definition, image histograms are a count of the number of pixels that are at a certain intensity. When represented as a plot, the x-axis is the intensity value, and the y-axis is the number of pixels with that intensity value. Intensity histogram is sometimes referred to as a bar graph of intensity in general terminology and seems fit as per the description.
Thanks