WiseImage – User’s Guide
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2. Start the operation without selecting an image.
Select an image you want to process from the dialog box.
*
For more detailed information on the selection procedure see “Selecting
Several Images” on page 20.
The following dialog box is displayed:
3. Use the appropriate boxes or sliders to modify the value of the following
parameters:
Brightness, Contrast, Hue,
and
Saturation
.
The preview window displays the effect of modifying the parameters.
4. Click
Apply
to run the operation.
Correction by Histogram
This operation is applied for precise adjustment of image brightness, hue, and
contrast. The algorithm for correction by histogram requires the specification of two
threshold brightness levels – the brightest and darkest pixels, and image gamma
that defines the position of the middle brightness value relative to the current
threshold values.
The gamma defines a ratio of brightness range length between the average and the
brightest value to the length of the brightness range between the dark threshold and
the average value. As a result, the pixels with brightness value below the dark
threshold gain zero brightness value; the pixels with a brightness value above the
brightest one gain maximum brightness value (255), and the brightness values of
the pixels between the darkest and the middle values, as well as between the
middle and the brightest ones, are relocated evenly in conformance with their range
lengths determined by the image gamma.
The increase of the gamma value causes the range for brightness values in the
dark range to reduce, and therefore it increases the contrast, at the same time
reducing the contrast in the light hue area, and vice versa.
The command enables the redistribution of both the image pixels’ average
brightness and brightness by separate color pixel components (Red, Green, and
