Broadcast fertilizer distribution through spinner-disc spreaders remain the most cost-effective, and least time consuming process to apply the needed soil amendments for the next crop. Spreaders currently available to producers enable them to apply a variety of granular products at varying rates, blends, and swath widths. In order to uniformly apply granular fertilizer or lime, the spreader should be calibrated by standard pan testing with any change in spreader settings, application rate, or fertilizer source. Improper or lack of calibration can result in nutrient “streaking” across the field, which is undesirable because it induces variability in crop fertility levels. The standard pan testing process includes a cumbersome technique of measuring the mass of fertilizer particles collected in each pan. Often, due to time restrictions operators cannot or choose not to calibrate their spinner-disc spreaders. An accurate and time efficient way to measure the spread pattern is required to ensure that proper calibration procedures are being adopted at an acceptable rate. Using image processing techniques, a user friendly application for graphical user interface was developed to assess the spread pattern uniformity of commercial-scale, spinner-disc spreaders.  In this app, the operator captures an image of the fertilizer particles in each collection pan. Images are then analyzed in order to detect the blend of fertilizer and to quantify mass of applied fertilizer particles in the collection pan.  Data from image analysis for each of the pans is then aggregated and combined with inputs from the user to generate an observed application rate across the swath and a spread pattern uniformity assessment. Results prove that the image based application is just as accurate as traditional pan testing, but less time consuming. Overall, this app will encourage calibration of spreaders while simultaneously reducing time and labor costs of operation.