#include "iqa.h"
#include "convolve.h"
#include "decimate.h"
#include "math_utils.h"
#include "ssim.h"
#include <stdlib.h>
#include <math.h>

Functions
static IQA_INLINE double	_calc_luminance (float, float, float, float)
static IQA_INLINE double	_calc_contrast (double, float, float, float, float)
static IQA_INLINE double	_calc_structure (float, double, float, float, float, float)
static int	_ssim_map (const struct _ssim_int , void )
static float	_ssim_reduce (int, int, void *)
float	iqa_ssim (const unsigned char ref, const unsigned char cmp, int w, int h, int stride, int gaussian, const struct iqa_ssim_args *args)
float	_iqa_ssim (float ref, float cmp, int w, int h, const struct _kernel k, const struct _map_reduce mr, const struct iqa_ssim_args *args)

Function Documentation

static IQA_INLINE double _calc_contrast	(	double	sigma_comb_12,
		float	sigma1_sqd,
		float	sigma2_sqd,
		float	C2,
		float	beta
	)		`[static]`

Definition at line 291 of file ssim.c.

static IQA_INLINE double _calc_luminance	(	float	mu1,
		float	mu2,
		float	C1,
		float	alpha
	)		`[static]`

Definition at line 276 of file ssim.c.

static IQA_INLINE double _calc_structure	(	float	sigma_12,
		double	sigma_comb_12,
		float	sigma1,
		float	sigma2,
		float	C3,
		float	gamma
	)		`[static]`

Definition at line 306 of file ssim.c.

float _iqa_ssim	(	float *	ref,
		float *	cmp,
		int	w,
		int	h,
		const struct _kernel *	k,
		const struct _map_reduce *	mr,
		const struct iqa_ssim_args *	args
	)

Private method that calculates the SSIM value on a pre-processed image.

The input images must have stride==width. This method does not scale.

Note:: Image buffers are modified.

Map-reduce is used for doing the final SSIM calculation. The map function is called for every pixel, and the reduce is called at the end. The context is caller-defined and *not* modified by this method.

Parameters:

ref	Original reference image
cmp	Distorted image
w	Width of the images
h	Height of the images
k	The kernel used as the window function
mr	Optional map-reduce functions to use to calculate SSIM. Required if 'args' is not null. Ignored if 'args' is null.
args	Optional SSIM arguments for fine control of the algorithm. 0 for defaults. Defaults are a=b=g=1.0, L=255, K1=0.01, K2=0.03

Returns:: The mean SSIM over the entire image (MSSIM), or NAN if error.

Definition at line 142 of file ssim.c.

int _ssim_map	(	const struct _ssim_int *	si,
		void *	ctx
	)		`[static]`

Definition at line 260 of file ssim.c.

float _ssim_reduce	(	int	w,
		int	h,
		void *	ctx
	)		`[static]`

Definition at line 268 of file ssim.c.

float iqa_ssim	(	const unsigned char *	ref,
		const unsigned char *	cmp,
		int	w,
		int	h,
		int	stride,
		int	gaussian,
		const struct iqa_ssim_args *	args
	)

Calculates the Structural SIMilarity between 2 equal-sized 8-bit images.

See https://ece.uwaterloo.ca/~z70wang/publications/ssim.html

Note:: The images must have the same width, height, and stride.

Parameters:

ref	Original reference image
cmp	Distorted image
w	Width of the images
h	Height of the images
stride	The length (in bytes) of each horizontal line in the image. This may be different from the image width.
gaussian	0 = 8x8 square window, 1 = 11x11 circular-symmetric Gaussian weighting.
args	Optional SSIM arguments for fine control of the algorithm. 0 for defaults. Defaults are a=b=g=1.0, L=255, K1=0.01, K2=0.03

Returns:: The mean SSIM over the entire image (MSSIM), or INFINITY if error.

Definition at line 59 of file ssim.c.

Functions

Function Documentation