Method and apparatus for witness card statistical analysis using image processing techniques

A method for assessing a spray using image processing techniques to analyze a scan image of an as-sprayed witness card, wherein the as-sprayed witness card includes a fixed pattern of stains as a result of being sprayed with drops of a selected fluid, the method comprising:

• (a) generating a scan image of a calibration witness card and a scan image of at least one as-sprayed witness card, wherein the calibration witness card includes a plurality of stains, each stain created with a known volume of the selected fluid;
• (b) identifying a plurality of stains within a scan image and determining a value for a selected dimensional characteristic for each identified stain based upon image processing of the scan image;
• (c) determining a calibration equation based upon values determined for stains identified within the calibration witness card scan image, wherein the calibration equation approximates a relationship between the determined calibration witness card stain values and the respective volumes of the selected fluid that created each respective calibration witness card stain;
• and
• (d) determining an as-sprayed drop characteristic based upon a value determined for a stain identified within the as-sprayed witness card scan image and the developed calibration equation.

A program product apparatus having a computer readable medium with computer program logic recorded thereon for assessing a spray using image processing techniques to analyze a scan image of an as-sprayed witness card, wherein the as-sprayed witness card includes a fixed pattern of stains as a result of being sprayed with drops of a selected fluid, said program product apparatus comprising:

• a scanner unit to generate a scan image of a calibration witness card and a scan image of at least one as-sprayed witness card, wherein the calibration witness card includes a plurality of stains, each stain created with a known volume of the selected fluid;
• an image analysis unit to identify a plurality of stains within a scan image and to determine a value for a selected dimensional characteristic for each identified stain based upon image processing of the scan image;
• a calibration unit to develop a calibration equation based upon values determined for stains identified within the calibration witness card scan image, wherein the calibration equation approximates a relationship between the determined calibration witness card stain values and the respective volumes of the selected fluid that created each respective calibration witness card stain;
• and
• a statistics unit to determine an as-sprayed drop characteristic based upon a value determined for a stain identified within the as-sprayed witness card scan image and the developed calibration equation.

A method for calibrating a system for assessing a spray using image processing techniques to analyze a scan image of an as-sprayed witness card, wherein the as-sprayed witness card includes a fixed pattern of stains as a result of being sprayed with drops of a selected fluid, the method comprising:

• (a) generating a scan image of a calibration witness card, wherein the calibration witness card includes a plurality of stains, each stain created with a known volume of the selected fluid;
• (b) identifying a plurality of stains within the scan image and determining a value for a selected dimensional characteristic for each identified stain based upon image processing of the scan image;
• and
• (c) determining a calibration equation based upon values determined for stains identified within the calibration witness card scan image, wherein the calibration equation approximates a relationship between the determined calibration witness card stain values and the respective volumes of the selected fluid that created each respective calibration witness card stain;
• wherein the calibration equation is used for determining an as-sprayed drop characteristic based upon a value determined for a stain identified within the as-sprayed witness card scan image and the developed calibration equation.