Class PeakSignalToNoiseRatio

Implements the Peak Signal-to-Noise Ratio (PSNR) metric for texture/image comparison. PSNR (in dB) is derived from the mean squared error (MSE) between a reference and a test image and depends on the peak pixel value (e.g., 255 for 8‑bit images). PSNR is commonly used to evaluate the fidelity of compressed images/video: higher values generally indicate better quality. Typical PSNR values for lossy compression often fall in the 30–50 dB range, though this depends on content, bit depth, resolution, and viewing conditions. Distortions are more likely to be perceptible below ~30–35 dB, while values above ~40 dB are often considered high quality. PSNR is a simple, non-perceptual metric; for perceptual assessment it should be complemented with other measures such as SSIM or color-difference metrics (e.g. DeltaE).

Inheritance
object
TextureComparisonAlgorithm
PeakSignalToNoiseRatio
Inherited Members
Namespace: UnityEngine.TestTools.Graphics
Assembly: UnityEngine.TestTools.Graphics.dll
Syntax
public class PeakSignalToNoiseRatio : TextureComparisonAlgorithm

Constructors

PeakSignalToNoiseRatio(ITextureComparisonSettings)

Initialized a new instance of the Peak Signal to Noise Ratio (PSNR) algorithm with the given threshold.

Declaration
public PeakSignalToNoiseRatio(ITextureComparisonSettings settings)
Parameters
Type Name Description
ITextureComparisonSettings settings

Ratio under which the test constraint fails

Methods

Compare(Texture2D, Texture2D)

Compares two Texture2D and returns a Peak Signal to Noise Ratio.

Declaration
public override ITextureComparisonResult Compare(Texture2D expected, Texture2D actual)
Parameters
Type Name Description
Texture2D expected

The reference texture
Texture2D actual

The texture being evaluated
Returns
Type Description
ITextureComparisonResult

The Peak Signal To Noise Ratio. higher being better, 30 being the human perceptible threshold.
Overrides

Compare(Texture2D[], Texture2D[])

Compares two arrays of textures using the Peak Signal to Noise Ratio (PSNR) algorithm. Both arrays need to have the same length and are compared by corresponding index.

Declaration
public override ITextureComparisonResult Compare(Texture2D[] expectedTextures, Texture2D[] actualTextures)
Parameters
Type Name Description
Texture2D[] expectedTextures

The reference textures
Texture2D[] actualTextures

The texture being evaluated
Returns
Type Description
ITextureComparisonResult

The Peak Signal To Noise Ratio. higher being better, 30 being the human perceptible threshold.
Overrides

CompareAsync(Texture2D, Texture2D)

Compares asynchronously two textures using the Peak Signal to Noise Ratio (PSNR) algorithm.

Declaration
public override Task<ITextureComparisonResult> CompareAsync(Texture2D expected, Texture2D actual)
Parameters
Type Name Description
Texture2D expected

The reference image
Texture2D actual

The texture being evaluated against the reference
Returns
Type Description
Task<ITextureComparisonResult>

A task with a result
Overrides
Exceptions
Type Condition
NotSupportedException

Async comparison is not supported for this algorithm

DescribeActual(ITextureComparisonResult)

Describes the measured values of a comparison result produced by this algorithm, as named values for structured result reporting. The algorithm owns the keys. Returns null when the algorithm does not provide structured values (or the result is not one of its own); reporting then falls back to the result's ToString().

Declaration
public override IReadOnlyDictionary<string, object> DescribeActual(ITextureComparisonResult result)
Parameters
Type Name Description
ITextureComparisonResult result

The result of a comparison run by this algorithm.
Returns
Type Description
IReadOnlyDictionary<string, object>

The measured values as named values, or null.
Overrides

DescribeExpected()

Describes the thresholds this algorithm compares against, as named values for structured result reporting. The algorithm owns the keys. Returns null when the algorithm does not provide structured values; reporting then falls back to Description.

Declaration
public override IReadOnlyDictionary<string, object> DescribeExpected()
Returns
Type Description
IReadOnlyDictionary<string, object>

The configured thresholds as named values, or null.
Overrides

Evaluate(ITextureComparisonResult)

Evaluates the comparison result against the defined threshold.

Declaration
public override (object, bool) Evaluate(ITextureComparisonResult result)
Parameters
Type Name Description
ITextureComparisonResult result

The PSNR comparison result
Returns
Type Description
(object, bool)

A tuple containing the result and whether it passes the evaluation
Overrides