Module 4D: Reading a Histogram

D. Reading a Histogram

 

 

                                       

Histograms  

Histograms are a graphic representation of the 256 tonal values of the pixels within the image. The horizontal graph represents the pixel’s numerical value from 0 (black) on the left to 255 (white) on the right. 

The graph represents an approximate 5 stop range. The blacks or shadows appear on the left side of the graph while the whites or highlights appear on the right side of the graph.

 

In the images below, the photograph of the black card produces a histogram where the values are all located to the left side of the graph near the “0” values. The graph indicates that there are no other pixels in the image with any other tonal values. 

                     

 

 

The image at the right of the gray card shows all of the pixel values in the image to be near the middle gray tonal values.

   

 

 

 Finally, in the images below, a white card was photographed, and the histogram shows all of the pixel values to be properly placed near the 255 values which represent white.