They moved through 30 different fields of view to ensure the statistical confidence required by the 2019 edition of the standard.
The standard provides tables and a formula (based on the binomial distribution) to determine the total number of point-phase hits needed. For a phase present at 10% volume fraction, you may need 1000–2000 total counts; for 50%, fewer counts are needed. astm e562-19e1
While modern image analysis software (like ImageJ or proprietary systems) can perform "automatic thresholding," ASTM E562 remains the primary validation method. They moved through 30 different fields of view
If the first few counts show high variability, the standard provides formulas to determine how many additional fields must be counted to meet the required precision level. 4. Manual vs. Automated Image Analysis you may need 1000–2000 total counts
