lut_trans — Transform an image with a gray-value look-up-table
lut_trans(Image : ImageResult : Lut : )
lut_trans transforms an image Image by using a gray
value look-up-table Lut. This table acts as a
transformation function. In the case of byte-images, Lut
has to be a tuple of length 256. In the case of int2-images,
Lut has to be a tuple of length 256 <= length <= 65536. If
the length of the Lut is <= 32768, the transformation is
applied to the positive gray values only, i.e., the first element of
the Lut specifies the new gray value for the gray value 0.
If the Lut is longer than 32768, exactly 65536 must be
passed. In this case, the positive and negative gray values are
transformed. In this case, the first element indicates the new gray
value for the gray value -32768 of the input image, while the last
element of the tuple indicates the new gray value for the gray value
32767. In all cases, the gray values of values outside the range of
Lut are set to 0. In the case of uint2-images,
Lut has to be a tuple of length 256 <= length <=
65536. Gray values outside the range of Lut are set to 0.
lut_trans can be executed on OpenCL devices.
Image (input_object) (multichannel-)image(-array) → object (byte* / int2* / uint2*) *allowed for compute devices
Image whose gray values are to be transformed.
ImageResult (output_object) (multichannel-)image(-array) → object (byte / int2 / uint2)
Transformed image.
Lut (input_control) integer-array → (integer)
Table containing the transformation.
* Apply a gamma correction to an image.
Gamma := 2.2
GammaLUT := []
for G := 0 to 255 by 1
GammaLUT := [GammaLUT,round(255.0*pow(G/255.0,1.0/Gamma))]
endfor
read_image (Image, 'mreut')
lut_trans (Image, ImageGamma, GammaLUT)
The operator lut_trans returns the value 2 (H_MSG_TRUE) if the
parameters are correct. Otherwise an exception is raised.
Foundation