Speckle Contrast
Calculate population speckle contrast from an intensity region.
Description
Population speckle contrast divides intensity standard deviation by mean intensity.
Population speckle contrast divides intensity standard deviation by mean intensity. It summarizes variation within a supplied region.1
Calculate population speckle contrast from an intensity region.
When to use Speckle Contrast
Use this tool to calculate population speckle contrast from an intensity region.
Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
How to use Speckle Contrast and understand its results
- Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
- Enter pixelIntensities using the field table and calculation rules, then run the tool.
- Read meanIntensity, standardDeviation, speckleContrast. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| pixelIntensities | Speckle pixel intensities | list of number | Required |
Enter nonempty finite pixel values with positive mean. Return mean, population deviation and contrast. Negative individual values are accepted; one positive pixel gives zero contrast.
contrast=sqrt(Σ(I−mean)²/n)/mean Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| meanIntensity | Mean intensity | number |
| standardDeviation | Population standard deviation | number; minimum: 0 |
| speckleContrast | Speckle contrast | number; minimum: 0 |
{
"input": {
"pixelIntensities": [
0,
2,
0,
2
]
},
"output": {
"meanIntensity": 1,
"standardDeviation": 1,
"speckleContrast": 1
}
}Limitations and assumptions
No region selection, camera correction or perfusion model is applied.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Speckle Decorrelation: Calculate frame-to-frame speckle correlation and decorrelation. For a complementary task, use Doppler-Flow Perfusion Index: Calculate a first-moment laser-Doppler perfusion index from a supplied spectrum.
References
-
Speckle Contrast — tool.io
Similar or alternative tools
- Speckle Decorrelation
Calculate frame-to-frame speckle correlation and decorrelation.
- Doppler-Flow Perfusion Index
Calculate a first-moment laser-Doppler perfusion index from a supplied spectrum.