Enhancing image and image colors

Description

Functions to enhance image colours.

Usage

    denoise(x, r=0, ...)
    mediansmooth(x, r=2, ...)
    despeckle(x, ...)

    sharpen(x, r=0, s=0.5, ...)
    umask(x, r=0, s=0.5, amount=5, t=2, ...)

    blur(x, r=0, s=0.5, ...)
    gblur(x, r=0, s=0.5, ...)

    noise(x, type="gaussian", ...)

Arguments

x

An object of Image-class.

r

The radius of the pixel neighbourhood to take into account. The 0 value enables automatic radius selection.

s

The standard deviation of the Laplacian (sharpen) or Gaussian (umask, blur, gblur), in pixels. For reasonable results of most functions, r must be larger than s.

amount

The percentage of the difference between the original and the blur image that is added back into the original.

t

The threshold in pixels needed to apply the diffence amount.

type

The type of noise to add.

...

Reserved for future use.

Value

A transformed image in an object of Image-class.

Details

despeckle reduces the speckle noise.

mediansmooth smoothes a noisy image by replacing each pixel value by the median in a set of neighbouring pixels as defined by radius.

blur, gblur blur an image. blur differs from Gaussian blur, gblur, in that it uses a separable kernel which is faster but mathematically equivalent to the non-separable kernel (implemented in ImageMagick).

sharpen, umask sharpen an image. umask uses the unsharp mask algorithm. The the image is convolved with a Gaussian operator of the given radius and standard deviation, s.

noise adds noise to an image. Supported noise types are: 'uniform', 'gaussian' (default) , 'multi', 'impulse', 'laplace' and 'poisson'.

Author(s)

Copyright (c) 2005-2006 Oleg Sklyar : osklyar@ebi.ac.uk

References

ImageMagick: http://www.imagemagick.org.

See Also

Image-class