utility.h File Reference

Common utility functions. More...

Functions
int	wv_log2i (int max_val)
	Integer logarithm base 2 of a given integer.
double	wv_mse_to_psnr (const double mse)
	Converts MSE (mean square error) to PSNR (peak signal to noise ration (dB)).
double	wv_psnr_to_mse (const double psnr)
	Converts PSNR (peak signal to noise ration (dB)) to MSE (mean square error).
double	wv_calc_psnr (const wv_pel *a, const wv_pel *b, const int width, const int height, const int pitch, double *pmse)
	Computes the PSNR (peak signal to noise ratio (dB)) and optionally the mean-square error from two version of an image.
int	wv_rgb_to_ycocg (const int Num, wv_pel *R, wv_pel *G, wv_pel *B)
	Converts an array of pixels (given as seperate bitplanes) from the RGB color-space into the YCoCg color-space.
int	wv_ycocg_to_rgb (const int Num, wv_pel *Y, wv_pel *Cb, wv_pel *Cr)
	Converts an array of pixels (given as seperate bitplanes) from the YCoCg color-space into the RGB color-space.
int	wv_rgb_to_ycocgr (const int Num, wv_pel *R, wv_pel *G, wv_pel *B)
	Converts an array of pixels (given as seperate bitplanes) from the RGB color-space into the YCoCg-R color-space.
int	wv_ycocgr_to_rgb (const int Num, wv_pel *Y, wv_pel *Cb, wv_pel *Cr)
	Converts an array of pixels (given as seperate bitplanes) from the YCoCg-R color-space into the RGB color-space.

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Detailed Description

Common utility functions.

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Function Documentation

double wv_calc_psnr	(	const wv_pel *	a,
		const wv_pel *	b,
		const int	width,
		const int	height,
		const int	pitch,
		double *	pmse
	)

Computes the PSNR (peak signal to noise ratio (dB)) and optionally the mean-square error from two version of an image.

Parameters:

[in]	a	Image A
[in]	b	Image B
[in]	width	Width of the image in a and b
[in]	height	Height of the image in a and b
[in]	pitch	Pitch in wv_pel units of the image in a and b (usually this is a power of 2)
[out]	pmse	Address of a double where the mean-square error is written into (if != NULL)

Returns:

PSNR between the two versions of the image

int wv_log2i

(

int

v

)

Integer logarithm base 2 of a given integer.

This is equal to the number of bits needed to encode that number.

Warning:

Returns 0 for negative numbers!

Parameters:

[in]

v

number whose log is wanted

Returns:

Integer logarithm (base 2) of v (wv_log2i(0) = 0)

double wv_mse_to_psnr

(

const double

mse

)

Converts MSE (mean square error) to PSNR (peak signal to noise ration (dB)).

Inverse of wv_psnr_to_mse().

Parameters:

[in]

mse

Mean square error

Returns:

PSNR (in dB) of given MSE. The result is 0 (instead of "infinity") for non-positive values.

double wv_psnr_to_mse

(

const double

psnr

)

Converts PSNR (peak signal to noise ration (dB)) to MSE (mean square error).

Inverse of wv_mse_to_psnr().

Parameters:

[in]

psnr

Peak signal to noise ration (in dB)

Returns:

Mean square error of given PSNR. The result is 1e64 for non-positive values

int wv_rgb_to_ycocg	(	const int	Num,
		wv_pel *	R,
		wv_pel *	G,
		wv_pel *	B
	)

Converts an array of pixels (given as seperate bitplanes) from the RGB color-space into the YCoCg color-space.

Inverse of wv_ycocg_to_rgb().

Parameters:

[in]	Num	Number of pixels to be converted
[in,out]	R	Red pixels on input, Y pixels on output
[in,out]	G	Green pixels on input, Co pixels on output
[in,out]	B	Blue pixels on input, Cg pixels on output

Returns:

Number of pixels converted

int wv_rgb_to_ycocgr	(	const int	Num,
		wv_pel *	R,
		wv_pel *	G,
		wv_pel *	B
	)

Converts an array of pixels (given as seperate bitplanes) from the RGB color-space into the YCoCg-R color-space.

Inverse of wv_ycocgr_to_rgb(). This transform is reversible (i.e. lossless).

Parameters:

[in]	Num	Number of pixels to be converted
[in,out]	R	Red pixels on input, Y pixels on output
[in,out]	G	Green pixels on input, Co pixels on output
[in,out]	B	Blue pixels on input, Cg pixels on output

Returns:

Number of pixels converted

int wv_ycocg_to_rgb	(	const int	Num,
		wv_pel *	Y,
		wv_pel *	Co,
		wv_pel *	Cg
	)

Converts an array of pixels (given as seperate bitplanes) from the YCoCg color-space into the RGB color-space.

Inverse of wv_rgb_to_ycocg().

Parameters:

[in]	Num	Number of pixels to be converted
[in,out]	Y	Y pixels on input, red pixels on output
[in,out]	Co	Co pixels on input, green pixels on output
[in,out]	Cg	Cg pixels on input, blue pixels on output

Returns:

Number of pixels converted

int wv_ycocgr_to_rgb	(	const int	Num,
		wv_pel *	Y,
		wv_pel *	Co,
		wv_pel *	Cg
	)

Converts an array of pixels (given as seperate bitplanes) from the YCoCg-R color-space into the RGB color-space.

Inverse of wv_rgb_to_ycocgr(). This transform is reversible (i.e. lossless).

Parameters:

[in]	Num	Number of pixels to be converted
[in,out]	Y	Y pixels on input, red pixels on output
[in,out]	Co	Co pixels on input, green pixels on output
[in,out]	Cg	Cg pixels on input, blue pixels on output

Returns:

Number of pixels converted

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