histequal

Histogram equalization of input image. More...

Functions
AFAPI array	histequal (const array &in, const array &hist)
AFAPI array	histEqual (const array &in, const array &hist)
	C++ Interface for histogram equalization. More...
AFAPI af_err	af_hist_equal (af_array *out, const af_array in, const af_array hist)
	C Interface for histogram equalization. More...

Detailed Description

Histogram equalization of input image.

Histogram equalization is a method in image processing of contrast adjustment using the image's histogram.

Data normalization via histogram equalization

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Function Documentation

af_hist_equal()

AFAPI af_err af_hist_equal	(	af_array *	out,
		const af_array	in,
		const af_array	hist
	)

C Interface for histogram equalization.

Parameters

[out]	out	is an array with data that has histogram approximately equal to histogram
[in]	in	is the input array, non-normalized input (!! assumes values [0-255] !!)
[in]	hist	target histogram to approximate in output (based on number of bins)

Returns

AF_SUCCESS if the color transformation is successful, otherwise an appropriate error code is returned.

Note

in must be two dimensional.

histequal()

AFAPI array histequal	(	const array &	in,
		const array &	hist
	)

C++ Interface for histogram equalization.

    float input[] = {1, 2, 1, 1, 3, 6, 7, 8, 3};
    int nbins     = 10;
 
    size_t nElems = sizeof(input) / sizeof(float);
    array hist_in(nElems, input);
 
    array hist_out = histogram(hist_in, nbins);
 
    // input after histogram equalization or normalization
    // based on histogram provided
    array eq_out = histEqual(hist_in, hist_out);
    // eq_out = { 1.5, 4.5,  1.5, 1.5, 4.5, 4.5, 6.0, 7.5, 4.5 }

Parameters

[in]	in	is the input array, non-normalized input (!! assumes values [0-255] !!)
[in]	hist	target histogram to approximate in output (based on number of bins)

Returns

data with histogram approximately equal to histogram

Note

in must be two dimensional.

Deprecated:

Use histEqual instead

histEqual()

AFAPI array histEqual	(	const array &	in,
		const array &	hist
	)

C++ Interface for histogram equalization.

    float input[] = {1, 2, 1, 1, 3, 6, 7, 8, 3};
    int nbins     = 10;
 
    size_t nElems = sizeof(input) / sizeof(float);
    array hist_in(nElems, input);
 
    array hist_out = histogram(hist_in, nbins);
 
    // input after histogram equalization or normalization
    // based on histogram provided
    array eq_out = histEqual(hist_in, hist_out);
    // eq_out = { 1.5, 4.5,  1.5, 1.5, 4.5, 4.5, 6.0, 7.5, 4.5 }

Parameters

[in]	in	is the input array, non-normalized input (!! assumes values [0-255] !!)
[in]	hist	target histogram to approximate in output (based on number of bins)

Returns

data with histogram approximately equal to histogram

Note

in must be two dimensional.