Levels Test

Self administered test on Levels

Question 1.  In Figure 1 below are seven variations of the same image labeled A, B, C, D, E, F and G.  Each is different because of a Levels adjustment.  In Figure 2 below are seven Levels dialog boxes labeled 1, 2, 3, 4, 5, 6 and 7.  Match the dialog box in Figure 2 to the resulting image in Figure 1.  The original image and its original dialog box are also shown.

Hint.

• Image A compared to the original is lighter overall, but contrast has been flattened.
• Image B has more whites and more blacks for greater contrast than the original.
• Image C has lighter highlights while the shadow areas remain unchanged (Image B has deeper shadows than image C).
• Image D is darker overall, but contrast has been reduced.
• Image E's original mid tones are lighter while maintaining some contrast in the shadows and highlights (Image C highlights are lighter).
• Image F has reduced overall contrast with no deep shadows and no true highlights (Image D has deeper shadow areas than image F).
• Image G has darker shadows without affecting highlights, giving a slight increase in contrast.  (Image B highlights are lighter).

Double Hint.  Because of the vast differences in monitor's ability to show tonal differences, it may be easier to find the correct Levels dialog box based on the description instead of the image.

Triple Hint.  If the image's contrast has increased, suspect Input Levels.  If the contrast has decreased, suspect Output Levels.

• Answer

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Figure 1.	Figure 2.

Question 2.  Figure 3 shows two images.  Image A has whites where there were blacks and has blacks where there were whites.  Image B is similar to the original in Figure 1 above.  Match the dialog box in Figure 4 to the resulting image in Figure 3.

1. Answer
   1. Image A and Levels 1
   2. Image B and Levels 2
      
      
   3. In Levels 1, the Output Levels sliders are reversed.  Therefore, highlights in the image became shadows and shadows became highlights.  Hence, Levels 1 created image A.  Even though tone has been reversed, contrast has neither increased nor decreased.
      
      Input Levels controls the image's tonal range.  When we move the Input Levels sliders inward, we are stretching the image's tonal range to fill more of the digital tonal range.  In Levels 2 below, we stretched the image's tonal range but we also moved the Output Levels sliders in by the same amount.  This compressed the digital tonal range the exact same amount the image's tonal range was stretched.  Therefore, each adjustment cancelled the other.  Resulting in an image that looks like the original.

Figure 3.	Figure 4.