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psnr

Peak signal-to-noise ratio (PSNR)

Description

example

peaksnr = psnr(A,ref) calculates the peak signal-to-noise ratio (PSNR) for the image A, with the image ref as the reference.

peaksnr = psnr(A,ref,peakval) calculates the PSNR of image A using the peak signal value peakval.

[peaksnr,snr] = psnr(___) also returns the simple signal-to-noise ratio, snr.

Examples

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Read image and create a copy with added noise. The original image is the reference image.

ref = imread('pout.tif');
A = imnoise(ref,'salt & pepper', 0.02);

Calculate the PSNR.

[peaksnr, snr] = psnr(A, ref);
  
fprintf('\n The Peak-SNR value is %0.4f', peaksnr);
 The Peak-SNR value is 22.6437
fprintf('\n The SNR value is %0.4f \n', snr);
 The SNR value is 15.5524 

Input Arguments

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Image to be analyzed, specified as a numeric array of any dimension.

Data Types: single | double | int16 | uint8 | uint16

Reference image, specified as a numeric array of the same size and data type as image A.

Data Types: single | double | int16 | uint8 | uint16

Peak signal level, specified as a nonnegative number. If not specified, the default value for peakval depends on the class of A and ref.

  • If the images are of data type double or single, then psnr assumes that image data is in the range [0, 1]. The default value of peakval is 1.

  • If the images are of integer data types, then the default value of peakval is the largest value allowed by the range of the class. For uint8 data, the default value of peakval is 255. For uint16 or int16, the default is 65535.

Output Arguments

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PSNR in decibels, returned as a scalar of type double, except if A and ref are of class single, in which case peaksnr is of class single.

Data Types: single | double

Signal-to-noise ratio in decibels, returned as a numeric scalar of type double, except if A and ref are of class single, in which case peakval is of type single.

Data Types: single | double

Algorithms

The psnr function implements this equation to calculate PSNR:

PSNR=10log10(peakval2/MSE)

peakval is either specified by the user or taken from the range of the image data type. For example, for image of uint8 data type, then peakval is 255. MSE is the mean square error between A and ref.

Extended Capabilities

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Introduced in R2014a