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The value of the lower limit for the colour range appears in the Minimum Input field.
5 Position the cursor on the white triangle below the histogram. Drag left to brighten in the highlight
areas in the image.
The value of the upper limit for the colour range appears in the Maximum Input field.
NOTE If you are in Luminance, you can invert the image by reversing the order of the black and white
triangles.
6 To cancel the changes, click Reset Basics.
Reducing Image Contrast
The slider controls on the gradient bar below the histogram are the Output Level controls. These controls
are used to set the range of colours used in the image:
■ The white triangle on the right sets the maximum value for the range.
■ The black triangle on the left sets the minimum value for the range.
You can use the Output Level controls to decrease the contrast in the image. For example, suppose that you
set the minimum value to 100. A pixel with a colour value of 0 is remapped to 100. Pixels with colour values
greater than 0 are remapped to the appropriate values. This has the effect of lightening the image and
decreasing the contrast in the shadow areas.
Suppose that you set the maximum value for the range to 200. A pixel with a colour value of 255 is remapped
to 200. Pixels with colour values less than 255 are remapped to the corresponding values. This has the effect
of darkening the image and decreasing the contrast in the highlight areas.
You can also set the maximum and minimum limits for the colour range by setting the values directly in
the Minimum and Maximum Output fields.
To reduce the contrast in an image:
1 Display the Histogram menu.
2 Click the Master, Shadows, Midtones, or Highlights button to select the parts of the image you want
to modify.
3 From the Channel Selection box, select Luminance, Red, Green, or Blue as the channel you want to
work with.
4 Position the cursor on the black triangle below the Output Level bar. Drag right to lighten the shadow
areas in the image.
The value of the lower limit for the colour range appears in the Minimum Output field.
5 Position the cursor on the white triangle below the gradient bar. Drag left to decrease the brightness
in the highlight areas.
The value of the upper limit appears in the Maximum Output field.
Defining Luma Ranges
Use the histogram in the Ranges menu to modify the shadow, midtone, or highlight ranges.
When working with 16-bit floating point images, the values of the histogram are represented on a logarithmic
scale. When working with integer images (8, 10, or12-bit), the values of the histogram are represented on a
linear scale.
800 | Chapter 19 Colour Correcting