imdiff.c File Reference

Image difference calculator program. More...

Detailed Description

Image difference calculator program.

Author

Pascal Getreuer getre.nosp@m.uer@.nosp@m.cmla..nosp@m.ens-.nosp@m.cacha.nosp@m.n.fr

This file implements the imdiff program, a command line tool for comparing two images with various image quality metrics. The possible metrics are

• Max absolute difference,
• Mean squared error,
• Root mean squared error,
• Peak signal-to-noise ratio,

where N is the number of pixels and subscript n denotes the nth pixel.

The program can also create a difference image, computed as

where values outside of the range [0,255] are saturated.

Note

Image alpha channels are ignored. Also beware that although the program can read 16-bit PNG images (provided USE_LIBPNG is enabled), the image data is quantized internally to 8 bits.

Copyright (c) 2010-2013, Pascal Getreuer All rights reserved.

This program is free software: you can redistribute it and/or modify it under, at your option, the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version, or the terms of the simplified BSD license.

You should have received a copy of these licenses along with this program. If not, see http://www.gnu.org/licenses/ and http://www.opensource.org/licenses/bsd-license.html.

Definition in file imdiff.c.

#include <ctype.h>
#include <math.h>
#include <string.h>
#include "imageio.h"

Go to the source code of this file.

Data Structures
struct	programparams
	struct of program parameters. More...

Macros
#define	DISPLAY_SCALING   255
	Display metrics for intensities in the range [0,DISPLAY_SCALING].

Enumerations
enum	metric_t {   DEFAULT_METRICS, MAX_METRIC, MSE_METRIC, RMSE_METRIC,   PSNR_METRIC }
	enum of possible metrics

Functions
void	make_difference_image (float *A, const float *B, int width, int height, int num_channels, float D)
	Make a difference image, diff = (A - B) / D + 0.5.
void	basic_metrics (float *max_diff, float *mse, const float *A, const float *B, int width, int height, int num_channels, int pad)
	Compute the maximum absolute difference and the MSE.
int	parse_params (programparams *param, int argc, char *argv[])
	Parse parameters from command line arguments.
void	print_help_message ()
	Print program usage help message.
int	main (int argc, char *argv[])