Patent ID: 8045752

Claim:
A witness card analysis method, comprising: selecting a fluid to be sprayed; positioning a witness card in an area to be sprayed; spraying the fluid such that drops of the fluid contact the witness card resulting in an as-sprayed witness card with a pattern of stains of the fluid thereon; exposing the as-sprayed witness card to a backlight sufficient to make the fixed pattern of stains visible; capturing an image of the pattern of stains while the as-sprayed witness card is being exposed to the backlight; processing the image of the pattern of stains to determine characteristics of the drops of the fluid on the as-sprayed witness card, wherein processing comprises using a calibration equation to assess characteristics of the pattern of stains on the as-sprayed witness card by comparing characteristics of the stains of the fluid on the as-sprayed witness card with characteristics of stains of the fluid on a calibration witness card, wherein the calibration equation is developed based on respective dimensions of a plurality of stains and known volume of the fluid for each stain on the calibration witness card; and generating statistics regarding the as-sprayed witness card using the calibration equation.