ImageHistModification

ImageHistModification [/A [/B=bins ][/C=cFactor ]] [/H=hRegions ] [/O/I] [/R=roiSpec ][/V=vRegions ][/W=waveName ] ImageMatrix

ImageHistModification performs a modification of the image histogram and saves the results in the wave M_ImageHistEq or as specified by the /DEST flag. If /W is not specified, the operation is a simple histogram equalization of ImageMatrix. If /W is specified, the operation attempts to produce an image with a histogram close to waveName. If /A is specified, the operation performs an adaptive histogram equalization. ImageMatrix is a wave of any noncomplex numeric type. Adaptive histogram equalization applies only to 2D waves while the remaining parts of the operation apply both to 2D and 3D waves.

Flags

/A	Performs an adaptive histogram equalization by subdividing the image into a minimum of 4 rectangular domains and using interpolation to account for the boundaries between adjacent domains. When the /C flag is specified with contrast factor greater than 1, this operation amounts to contrast-limited adaptive histogram equalization. By default the operation divides the image into 8 horizontal and 8 vertical regions. See /H and /V below.
/B=bins	Specify the number of bins used with the /A feature. If not specified, this value defaults to 256.
/C=cFactor	Specify a contrast factor (or clipping value) above which pixels are equally distributed over the whole range. cFactor must be greater than 1, in the limit as cFactor→1 the operation is a regular adaptive histogram equalization.
	note This flag is used only with the /A flag.
/DEST=destWave
	Specifies the output wave.
	When used in a function, ImageHistModification creates a real wave reference for the destWave. See Automatic Creation of Wave References for details.
	/DEST flag was added in Igor Pro 10.00.
/FREE	Creates destWave as a free wave.
	/FREE is allowed only in functions and only if destWave is a simple name or wave reference structure field.
	See Free Waves for more discussion.
	The /FREE flag was added in Igor Pro 10.00.
/H=hRegions	Specify the number of horizontal subdivisions to be used with the /A feature. Note, the number of image pixels in the horizontal direction must be an integer multiple of hRegions.
/I	This is an extension of standard histogram equalization that uses 216 bins instead of 28 when calculating histogram equalization. This feature does not apply to the adaptive histogram equalization (/A flag).
/O	Overwrites the source image. If this flag is not specified, the resulting image is saved in the wave M_ImageHistEq or as specified by the /DEST flag.
/R=roiSpec	Specify a region of interest (ROI). The ROI is defined by a wave of type unsigned byte (/b/u). The ROI wave must have the same number of rows and columns as the image wave. The ROI itself is defined by the entries/pixels whose values are 0. Pixels outside the ROI can take any nonzero value. The ROI does not have to be contiguous and can take any arbitrary shape.
	In general, the roiSpec has the form {roiWaveName, roiFlag}, where roiFlag can take the following values:
	0: Set pixels outside the ROI to 0 1: Set pixels outside the ROI as in original image 2: Set pixels outside the ROI to NaN (i.e., 64)
	By default roiFlag is set to 1 and it is then possible to use the /R flag using the abbreviated form /R=roiWave. When imageMatrix is a 3D wave, roiWave can be either a 2D wave as described above (matching the number of rows and columns in imageMatrix) or it can be a 3D wave which must have the same number of rows, columns, and layers as imageMatrix. When using a 2D roiWave with a 3D imageMatrix the ROI is understood to be defined by roiWave for each layer in the 3D wave.
	See ImageGenerateROIMask for more information on creating ROI waves.
/V=vRegions	Specifies the number of vertical subdivisions to be used with the /A flag. Note, the number of image pixels in the horizontal direction must be an integer multiple of vRegions . If the dimensions of the image are not divisible by the number of regions that you want, you can pad the image using ImageTransform with the padImage keyword.
/W=waveName	A 256-point wave that specifies the desired histogram. The operation will attempt to produce an image having approximately the desired histogram values. This flag does not apply to the adaptive histogram equalization (/A flag).

See Also

The ImageGenerateROIMask and ImageTransform operations for creating ROIs.

Image Processing