A method for antibiotic susceptibility testing using a processor comprising: providing a culture plate inoculated with a biological sample, the culture plate having culture media and at least one antibiotic disk disposed thereon; receiving first and second image data of the culture plate generated with an image sensor, the image data associated with image pixels, the first image data and second image data respectively representing first and second captured images of the culture plate having a plurality of antibiotic disks thereon, the first and second captured images taken at first and second times, wherein the culture plate is incubated between the first and second times and wherein, optionally, the first image data serves as a pre-growth reference; generating pixel characteristic data for pixels of the first and second image data from a comparison of the first image data and the second image data, the pixel characteristic data comprising contrast data wherein, optionally, the contrast data comprises pixel intensity values; identifying pixels associated with the at least one antibiotic disk in the image data; comparing the first and second image data to identify microbial growth on the culture plate by disregarding the pixels associated with the at least one antibiotic disk in the image data and identifying one or more pixel regions of the second image data that differ from one or more pixel regions of the first image data wherein the one or more pixel regions are adjacent to the antibiotic disks; evaluating microbial growth as it relates to distance from an edge of the antibiotic disk; providing pixel contrast information from the comparison of the first and second image data to identify microbial growth on the culture plate; applying a polar transformation of the contrast data thereby providing a disk portion into a light band with a first intensity, a no-growth band with a second intensity and a growth region with a third intensity wherein third intensity is less than the first intensity and greater than the second intensity; optionally detecting an edge between the pixels in the no-growth band and the growth region; and determining the minimum inhibitory distance for the at least one antibiotic disk based on a distance of the growth region from the at least one antibiotic disk. providing a culture plate inoculated with a biological sample, the culture plate having culture media and at least one antibiotic disk disposed thereon; receiving first and second image data of the culture plate generated with an image sensor, the image data associated with image pixels, the first image data and second image data respectively representing first and second captured images of the culture plate having a plurality of antibiotic disks thereon, the first and second captured images taken at first and second times, wherein the culture plate is incubated between the first and second times and wherein, optionally, the first image data serves as a pre-growth reference; generating pixel characteristic data for pixels of the first and second image data from a comparison of the first image data and the second image data, the pixel characteristic data comprising contrast data wherein, optionally, the contrast data comprises pixel intensity values; identifying pixels associated with the at least one antibiotic disk in the image data; comparing the first and second image data to identify microbial growth on the culture plate by disregarding the pixels associated with the at least one antibiotic disk in the image data and identifying one or more pixel regions of the second image data that differ from one or more pixel regions of the first image data wherein the one or more pixel regions are adjacent to the antibiotic disks; evaluating microbial growth as it relates to distance from an edge of the antibiotic disk; providing pixel contrast information from the comparison of the first and second image data to identify microbial growth on the culture plate; applying a polar transformation of the contrast data thereby providing a disk portion into a light band with a first intensity, a no-growth band with a second intensity and a growth region with a third intensity wherein third intensity is less than the first intensity and greater than the second intensity; optionally detecting an edge between the pixels in the no-growth band and the growth region; and determining the minimum inhibitory distance for the at least one antibiotic disk based on a distance of the growth region from the at least one antibiotic disk.