.\
cggmascl.pro
top cgGmaScl
Image Processing
result = cgGmaScl(image [, GAMMA=float] [, MAX=MAX] [, MIN=MIN], NEGATIVE=NEGATIVE [, OMAX=byte] [, OMIN=byte])
This is a utility routine to perform basic gray-level pixel transformations of images. I think of it as BYTSCL on steroids. It is similar to IMADJUST in _Digital Image Processing with MATLAB_ by Gonzales, Wood, and Eddins. It performs a log scaling of the image array.
Return value
A byte scaled image is returned.
Parameters
- image in required
The image to be scaled. Written for 2D images, but arrays of any size are treated alike.
Keywords
- GAMMA in optional type=float default=1.0
The exponent in a power-law transformation (image^gamma). A gamma value of 1 results in a linear distribution of values between OMIN and OMAX. Gamma values less than 1 map darker image values into a wider range of output values, and Gamma values greater than 1 maps lighter image values into a wider range of output values. The gamma value is constrained to be greater than 1.0e-6.
- MAX in optional
Any value in the input image greater than this value is set to this value before scaling.
- MIN in optional
Any value in the input image less than this value is set to this value before scaling.
- NEGATIVE
If set, the "negative" of the result is returned.
- OMAX in optional type=byte default=255
The output image is scaled between OMIN and OMAX.
- OMIN in optional type=byte default=0
The output image is scaled between OMIN and OMAX.
Examples
cgLoadCT, 0 ; Gray-scale colors. image = cgDemoData(11) ; Load image. TVImage, cgGmaScl(image, Min=30, Max=100) ; Similar to BytScl. TVImage, cgGmaScl(image, /Negative) ; Produce negative image. power = Shift(ALog(Abs(FFT(image,-1))), 124, 124) ; Create power spectrum. TVImage, cgGmaScl(power, Gamma=2.5) ; View power specturm with gamma correction. TVImage, cgGmaScl(power, Gamma=2.5, /Negative) ; Reverse power spectrum.
Author information
- Author:
FANNING SOFTWARE CONSULTING:
David W. Fanning 1645 Sheely Drive Fort Collins, CO 80526 USA Phone: 970-221-0438 E-mail: david@idlcoyote.com Coyote's Guide to IDL Programming: http://www.idlcoyote.com- Copyright:
Copyright (c) 2006-2015, Fanning Software Consulting, Inc.
- History:
Change History:
Written by: David W. Fanning, 17 February 2006. Fixed a problem with output scaling. 1 July 2009. DWF (with input from Bo Milvang-Jensen). Now setting NAN keyword on all MIN and MAX functions. 2 Dec 2011. DWF. Renamed cgGmaScl from GmaScl. 27 March 2015. DWF.
File attributes
| Modification date: | Fri Mar 27 08:03:22 2015 |
| Lines: | 160 |
| Docformat: | rst rst |