Project: Histograms

Exercise: Histogram

Find and shoot the three most basic categories of scene contrast.  These are low-contrast (that is,  flat in appearance with a low dynamic range), average contrast, and high contrast (with a dynamic range greater than that of the camera).  Then for each of these picture situations, shoot not only an averagely exposed version, but also one that is approximately one f-stop darker and another that is approximately one f-stop brighter.  In whatever processing software you use make sure the histogram is displayed, also making sure that the highlight and shadow clipping warnings are displayed.  Make a screenshot of each image and its histogram and write a short note about each explaining how they relate to each other and how exactly they vary with exposure.  Make a special note of the occasions on which highlight and shadow clipping occur and whether one is greater than the other.

Low-Contrast, No Bias

Low Contrast, No Exposure Bias

This image, of a painted wall, shows a histogram with a pixel column centrally on the display, as would be expected from a standard, low-contrast image where there is no variation in the dynamic range of the reflected image.

Low-Contrast -1EV Bias

Low Contrast -1EV Bias

This image, of the same wall, shows that when the camera is effectively made to shoot the image one f-stop lower than the optimum calculated by its computer system, then the pixel column is moved in its entirety to the shadow end of the histogram, as would be expected from the fact that the camera is being told to make the image less bright than with no bias.

Low-Contrast, +1EV Bias

Low Contrast, +1EV Bias

This image, again of the same wall, shows that when the camera is effectively made to shoot the image one f-stop greater than optimum calculated by its computer system, then the pixel column is moved in its entirety to the highlight end of the histogram, as would be expected from the fact that the camera is being told to make the image brighter than with no bias.

2 Responses to Project: Histograms

  1. Catherine says:

    Well explained Eddy.

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