OOF2: The Manual

OOF.Image.Modify.Contrast
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Name

OOF.Image.Modify.Contrast — Enhance intensity differences.

Synopsis

OOF.Image.Modify.Contrast(image, radius, mode)

Details

  • Parent Menu: OOF.Image.Modify
  • Callback: function doImageMod in module ooflib.image.imagemodifier

  • Parameters:

    image
    Type: The path to an existing Image object.
    radius
    Radius of the pixel neighborhood. Type: Integer.
    mode
    Operate on RGB channels separately, or only the V from HSV. Type: An object from the ModifierMode enumerated class.

Description

Enhance intensity differences between the lighter and darker portions of the given Image. The algorithm is similar to skimage.filters.rank.enhance_contrast in scikit-image. The scikit-image routine is faster, but the OOF2 version does not reduce the color channels to 8 bits.

In a grayscale image, the minimum and maximum intensities are found within a circle of the given radius (in pixel units) around each pixel. The central pixel is replaced with either the minimum or the maximum, depending on which is closer to the pixel's original value.

Figure 6.32. Adjusting Contrast in a Grayscale Image

Adjusting Contrast in a Grayscale Image

A 200×200 pixel grayscale image, left, and the results of enhancing its contrast with radius=5 and radius=10. The larger radius leads to higher contrast at the expense of detail.


In a color image, the algorithm is applied to the RGB channels independently if mode is RGB. If mode is HSV, the image is converted to HSV format, and the algorithm is applied only to the V channel.

Figure 6.33. Adjusting Contrast in a Color Image

Adjusting Contrast in a Color Image
A 200×200 pixel color image, left, and the results of enhancing its contrast at with different radiuses and different modes. HSV mode does a better job of preserving colors.

See Also

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OOF.Image.Modify.Blur  Home  OOF.Image.Modify.Denoise