Spectral analysis of biological growth media
This disclosure is directed to imaging techniques and image analysis techniques for automated analysis of biological growth media. According to this disclosure, the spectral responses of biological growth media can be used to identify and count biological agents from images of biological growth media. The biological growth media may be illuminated with two or more different wavelengths of electromagnetic radiation, and images of the biological growth media can be captured under these different illuminations. The spectral reflectance values in one or more first images can be normalized based on the spectral reflectance values in one or more second images, wherein the first images are associated with a different wavelength of illumination than the second images. The normalization may allow for better identification of biological agents that manifest on the biological growth media.
1. A method comprising:
illuminating a biological growth medium with a first electromagnetic radiation having a wavelength between approximately 700 and approximately 1000 nanometers;
generating one or more first images of the biological growth medium illuminated with the electromagnetic radiation outside the visible spectrum;
illuminating the biological growth medium with second electromagnetic radiation that is within the visible spectrum;
generating one or more second images of the biological growth medium illuminated with the second electromagnetic radiation; and
counting the biological agents on the biological growth medium based on the first and second images of the biological growth medium.
2. The method of claim 1 , wherein illuminating the biological growth medium with electromagnetic radiation having a wavelength between approximately 700 and approximately 1000 nanometers comprises illuminating the biological growth medium with light having a wavelength between approximately 800 and approximately 900 nanometers.
3. The method of claim 1 , further comprising:
normalizing spectral reflectance values in the one or more first images based on the one or more second images; and
identifying the biological agents based on the normalized spectral reflectance values; and
counting the identified biological agents.
4. The method of claim 3 , wherein:
the first electromagnetic radiation that is outside the visible spectrum comprises light having a wavelength between approximately 800 and approximately 900 nanometers; and
the second electromagnetic radiation that is within the visible spectrum comprises light having a wavelength between approximately 500 and approximately 700 nanometers.
5. The method of claim 1 , further comprising:
determining ratios of spectral reflectance in the one or more first images to spectral reflectance in the one or more second images;
identifying the biological agents based on the ratios; and
counting the identified biological agents.
6. The method of claim 5 , wherein:
normalizing spectral reflectance values in the one or more first images based on the one or more second images comprises determining ratios of spectral reflectance values in the one or more first images to spectral reflectance values in the one or more second images for different pixel locations; and
identifying the biological agents comprises comparing the ratios to one or more thresholds.
7. The method of claim 1 , further comprising:
storing a spectral profile associated with the biological growth medium; and
processing the biological growth medium based on the stored spectral profile.
8. A system comprising:
an imaging unit that illuminates a biological growth medium with first electromagnetic radiation having a wavelength between approximately 700 and approximately 1000 nanometers, generates one or more first images of the biological growth medium illuminated with the first electromagnetic radiation, illuminates the biological growth medium with second electromagnetic radiation that is within a visible spectrum, and generates one or more second images of the biological growth medium illuminated with the second electromagnetic radiation; and
a computer that normalizes spectral reflectance values in the one or more first images based on the one or more second images, identifies the biological agents based on the normalized spectral reflectance values, and counts the identified biological agents.
9. The system of claim 8 , wherein the first electromagnetic radiation is within a visible spectrum, and the second electromagnetic radiation is outside the visible spectrum.
10. The system of claim 9 , wherein:
the first electromagnetic radiation comprises light having a wavelength between approximately 800 and approximately 900 nanometers; and
the second electromagnetic radiation comprises light having a wavelength between approximately 500 and approximately 700 nanometers.
11. The system of claim 9 , wherein the computer:
stores a spectral profile associated with the biological growth medium; and
processes the biological growth medium based on the stored spectral profile.
12. The system of claim 9 , further comprising:
an inoculation unit that inoculates the biological growth medium; and
an incubation unit that incubates the biological growth medium.
13. The system of claim 9 , wherein the computer:
normalizes spectral reflectance values in the one or more first images based on the one or more second images by determining ratios of spectral reflectance values in the one or more first images to spectral reflectance values in the one or more second images for different pixel locations; and
identifies the biological agents by comparing the ratios to one or more thresholds.
14. A system comprising:
means for illuminating a biological growth medium with first electromagnetic radiation having a wavelength between approximately 700 and approximately 1000 nanometers;
means for illuminating a biological growth medium with second electromagnetic radiation that is within the visible spectrum;
means for generating one or more first images of the biological growth medium illuminated with the first electromagnetic radiation;
means for generating one or more second images of the biological growth medium illuminated with the second electromagnetic radiation; and
means for counting biological agents on the biological growth medium based on the one or more first images and the one or more second images.
15. A computer-readable medium comprising instructions that upon execution in a computer of a biological growth medium processing system cause the computer to:
receive one or more first images of the biological growth medium, the one or more first images having been generated during illumination of the biological growth medium with first electromagnetic radiation that is within a visible spectrum;
receive one or more second images of the biological growth medium, the one or more second images having been generated during illumination of the biological growth medium with second electromagnetic radiation having a wavelength between approximately 700 and approximately 1000 nanometers;
normalize spectral reflectance values in the one or more first images based on the one or more second images;
identify one or more biological agent based on the normalized spectral reflectance values; and
count the identified biological agents.