/* find histogram of x
 */
Hist_find x = map_unary hist_find x;

/* find n-dimensional histogram from n-band image
 */
Hist_find_nD in
	= map_unary widget in
{
	widget image = class 
		Image value {
		_check_args = [
			[image, "Image", check_Image]
		] ++ super._check_args;
		_vislevel = 3;

		// default to something small-ish
		bins = 8;

		value = hist_find_nD bins image.value;
	}
}

/* map image x through histogram hist
 */
Hist_map hist x = map_binary hist_map hist x;

/* find cumulative histogram of hist
 */
Hist_cumulative x = map_unary hist_cum x;

/* find normalised histogram of hist
 */
Hist_normalise x = map_unary hist_norm x;

/* find LUT which matches hist in to hist ref
 */
Hist_match in ref = map_binary hist_match in ref;

#separator

/* histogram equalisation
 */
Hist_equalise = class {
	/* histogram equalise x globally
	 */
	Global x = map_unary hist_equalize x;

	/* local histogram equalisation using region r as window
	 */
	Local r = map_unary (hist_equalize_local r.width r.height) r.image;
}

/* slice a line of pixels along a guide line and display as a histogram
 */
Guide_slice in
	= map_unary widget in
{
	widget guide = class 
		Image value {
		_check_args = [
			[guide, "Guide", check_Guide]
		] ++ super._check_args;

		value 
			= image_set_type Image_type.HISTOGRAM slice
		{
			slice
				= guide.image.extract_area 
					guide.image.rect.left guide.top 
					guide.width 1,
					is_instanceof "HGuide" guide
				= guide.image.extract_area
					guide.left guide.image.rect.top
					1 guide.height;
		}
	}
}