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Tutorial 2

How to improve the tonal range

In this tutorial, we will show you how to make tonal corrections to a digital image so that the color tone is more balanced between highlight (bright) and shadow (dark). You may also right click on this image and copy it to the Clipboard and use the Image Broadway File > Clipboard menu to paste it in as a new image. Optionally, you may click the Navigator tab to display the Navigator window and use its slider bar to zoom in and out; or you may click the Info tab to display the exact pixel color and cursor information in the Info window.

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  1. Figure 10.02.1 shows the original image, which overly emphasizes shadows. You may right click and save this image to your disk, then open it in Image Broadway if you want to practice it yourself while following the tutorial steps below. You may also right click and copy this image to the Clipboard, create a new image in Image Broadway and paste it in.

    Use the Adjust/Enhance > Brightness/Contrast > Levels menu to open the Levels dialog box. You can simply click the Auto button to automatically adjust the tonal range, or perform the following steps manually. To adjust it manually, you can adjust the Red, Green, and Blue channels in one adjustment or individually. The remaining steps are examples of how to adjust the channels individually.


    Figure 10.02.1

  2. Select the red channel and you will see in the histogram that most of the input comes from the shadow (dark) end of the scale. In order to make the most of available color information, you can move the black (left) and white (right) triangles in the Input box from the original 0-255 range to the 0-168 range as shown in Figure 10.02.2. This narrower Input tonal range (0-168) is mapped to a full Output range (0-255) so that muddier shadows are replaced by brighter tones with more details.

        
    Figure 10.02.2

  3. Apply the same method to the green and blue channels with results as shown in Figures 10.02.3 and 10.02.3b.

        
    Figure 10.02.3

        
    Figure 10.02.3b