source/ms_ssim.c File Reference

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

Go to the source code of this file.

Data Structures
struct	_context
Defines
#define	SCALES   5
#define	LPF_LEN   9
Functions
int	_ms_ssim_map (const struct _ssim_int *si, void *ctx)
float	_ms_ssim_reduce (int w, int h, void *ctx)
void	_free_buffers (float **buf, int scales)
int	_alloc_buffers (float **buf, int w, int h, int scales)
float	iqa_ms_ssim (const unsigned char *ref, const unsigned char *cmp, int w, int h, int stride, const struct iqa_ms_ssim_args *args)
Variables
static const float	g_lpf [LPF_LEN][LPF_LEN]
static float	g_alphas [] = { 0.0000f, 0.0000f, 0.0000f, 0.0000f, 0.1333f }
static float	g_betas [] = { 0.0448f, 0.2856f, 0.3001f, 0.2363f, 0.1333f }
static float	g_gammas [] = { 0.0448f, 0.2856f, 0.3001f, 0.2363f, 0.1333f }

---

Define Documentation

#define LPF_LEN   9

Definition at line 45 of file ms_ssim.c.

#define SCALES   5

Definition at line 42 of file ms_ssim.c.

---

Function Documentation

int _alloc_buffers	(	float **	buf,
		int	w,
		int	h,
		int	scales
	)

Definition at line 103 of file ms_ssim.c.

void _free_buffers	(	float **	buf,
		int	scales
	)

Definition at line 95 of file ms_ssim.c.

int _ms_ssim_map	(	const struct _ssim_int *	si,
		void *	ctx
	)

Definition at line 74 of file ms_ssim.c.

float _ms_ssim_reduce	(	int	w,
		int	h,
		void *	ctx
	)

Definition at line 84 of file ms_ssim.c.

float iqa_ms_ssim	(	const unsigned char *	ref,
		const unsigned char *	cmp,
		int	w,
		int	h,
		int	stride,
		const struct iqa_ms_ssim_args *	args
	)

Calculates the Multi-Scale Structural SIMilarity between 2 equal-sized 8-bit images. The default algorithm is MS-SSIM* proposed by Rouse/Hemami 2008.

See https://ece.uwaterloo.ca/~z70wang/publications/msssim.pdf and http://foulard.ece.cornell.edu/publications/dmr_hvei2008_paper.pdf

Note:

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

2. The minimum image width or height is 2^(scales-1) * filter, where 'filter' is 11 if a Gaussian window is being used, or 9 otherwise.

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.
args	Optional MS-SSIM arguments for fine control of the algorithm. 0 for defaults. Defaults are wang=0, scales=5, gaussian=1.

Returns:

The mean MS-SSIM over the entire image, or INFINITY if error.

Definition at line 129 of file ms_ssim.c.

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Variable Documentation

float g_alphas[] = { 0.0000f, 0.0000f, 0.0000f, 0.0000f, 0.1333f } [static]

Definition at line 59 of file ms_ssim.c.

float g_betas[] = { 0.0448f, 0.2856f, 0.3001f, 0.2363f, 0.1333f } [static]

Definition at line 60 of file ms_ssim.c.

float g_gammas[] = { 0.0448f, 0.2856f, 0.3001f, 0.2363f, 0.1333f } [static]

Definition at line 61 of file ms_ssim.c.

const float g_lpf[LPF_LEN][LPF_LEN] [static]

Initial value:

 {
   { 0.000714f,-0.000450f,-0.002090f, 0.007132f, 0.016114f, 0.007132f,-0.002090f,-0.000450f, 0.000714f},
   {-0.000450f, 0.000283f, 0.001316f,-0.004490f,-0.010146f,-0.004490f, 0.001316f, 0.000283f,-0.000450f},
   {-0.002090f, 0.001316f, 0.006115f,-0.020867f,-0.047149f,-0.020867f, 0.006115f, 0.001316f,-0.002090f},
   { 0.007132f,-0.004490f,-0.020867f, 0.071207f, 0.160885f, 0.071207f,-0.020867f,-0.004490f, 0.007132f},
   { 0.016114f,-0.010146f,-0.047149f, 0.160885f, 0.363505f, 0.160885f,-0.047149f,-0.010146f, 0.016114f},
   { 0.007132f,-0.004490f,-0.020867f, 0.071207f, 0.160885f, 0.071207f,-0.020867f,-0.004490f, 0.007132f},
   {-0.002090f, 0.001316f, 0.006115f,-0.020867f,-0.047149f,-0.020867f, 0.006115f, 0.001316f,-0.002090f},
   {-0.000450f, 0.000283f, 0.001316f,-0.004490f,-0.010146f,-0.004490f, 0.001316f, 0.000283f,-0.000450f},
   { 0.000714f,-0.000450f,-0.002090f, 0.007132f, 0.016114f, 0.007132f,-0.002090f,-0.000450f, 0.000714f},
}

Definition at line 46 of file ms_ssim.c.