Single-pass primary analysis
Methods and systems for image analysis are provided, and in particular for identifying a set of base-calling locations in a flow cell for DNA sequencing. These include capturing flow cell images after each sequencing step performed on the flow cell, and identifying candidate cluster centers in at least one of the flow cell images. Intensities are determined for each candidate cluster center in a set of flow cell images. Purities are determined for each candidate cluster center based on the intensities. Each candidate cluster center with a purity greater than the purity of the surrounding candidate cluster centers within a distance threshold is added to a template set of base-calling locations.
1. A method for identifying one or more base-calling locations in a sample on a flow cell comprising:
obtaining a first plurality of flow cell images corresponding to different fluorescent wavelengths, wherein the first plurality of flow cell images represents the flow cell in one or more flow cycles, and wherein each wavelength of the different fluorescent wavelengths corresponds to a respective nucleotide base,
identifying one or more DNA cluster centers in the first plurality of flow cell images by applying a spot-finding algorithm based on pixel intensity and relative color purity of the plurality of flow cell images; and
generating a template by mapping a plurality of base-calling locations corresponding to the identified one or more DNA cluster centers onto the template, wherein the template is configured for registering a second plurality of flow cell images acquired of the flow cell in one or more subsequent flow cycles to the template.
2. The method of claim 1 , wherein identifying the one or more DNA cluster centers in the first plurality of flow cell images by applying the spot-finding algorithm is at a sub-pixel resolution.
3. The method of claim 1 , wherein a wavelength of an optical signal detected at the one or more DNA cluster centers in a flow cycle correlates to a nucleotide base added to the one or more DNA cluster centers in the flow cycle.
4. The method of claim 1 , wherein the template is further configured for aligning each of the second plurality of flow cell images with the template.
5. The method of claim 1 , wherein the pixel intensity comprises a corresponding pixel intensity at each of the one or more DNA cluster centers.
6. The method of claim 5 , wherein the corresponding pixel intensity is determined based on a comparison of a set of channel intensities at the corresponding DNA cluster center of the one or more DNA cluster centers, each channel intensity in the set of channel intensities corresponding to a respective different fluorescent wavelength.
7. The method of claim 1 , further comprising:
identifying one or more nucleotide bases added at each of the plurality base-calling locations in one or more subsequent flow cycles based on the template.
8. The method of claim 1 , wherein mapping the plurality of base-calling locations corresponding to the identified DNA cluster centers onto the template comprises generating coordinates of the plurality of base-calling locations in a common coordinate system.
9. A system for identifying one or more base-calling locations in a sample on a flow cell, the system comprising:
data storage; and
one or more processors coupled to the data storage and configured to:
obtain a first plurality of flow cell images corresponding to different fluorescent wavelengths, wherein the first plurality of flow cell images represents the flow cell in one or more flow cycles, and wherein each wavelength of the different fluorescent wavelengths corresponds to a respective nucleotide base;
identifying one or more DNA cluster centers in the first plurality of flow cell images by applying a spot-finding algorithm based on pixel intensity and relative color purity of the plurality of flow cell images, and
generating a template by mapping a plurality of base-calling locations corresponding to the identified one or more DNA cluster centers onto the template, wherein the template is configured for registering a second plurality of flow cell images acquired of the flow cell in one or more subsequent flow cycles to the template.
10. The system of claim 9 , wherein identifying the one or more DNA cluster centers in the first plurality of flow cell images by applying the spot-finding algorithm is at a sub-pixel resolution.
11. The system of claim 9 , wherein a wavelength of an optical signal detected at the one or more DNA cluster centers in a flow cycle correlates to a nucleotide base added to the one or more DNA cluster centers in the flow cycle.
12. The system of claim 9 , wherein the template is further configured for aligning each of the second plurality of flow cell images with the template.
13. The system of claim 9 , wherein the pixel intensity comprises a corresponding pixel intensity at each of the one or more DNA cluster centers.
14. The system of claim 13 , wherein the corresponding pixel intensity is determined based on a comparison of a set of channel intensities at the corresponding DNA cluster center of the one or more DNA cluster centers, each channel intensity in the set of channel intensities corresponding to a respective different fluorescent wavelength.
15. The system of claim 9 , wherein the operations further comprise:
identifying one or more nucleotide bases added at each of the plurality base-calling locations in one or more subsequent flow cycles based on the template.
16. The system of claim 9 , wherein mapping the plurality of base-calling locations corresponding to the identified DNA cluster centers onto the template comprises generating coordinates of the plurality of base-calling locations in a common coordinate system.
17. A non-transitory computer readable storage medium having computer readable code thereon, the non-transitory computer readable medium including instructions configured to cause a computer system to perform operations comprising:
obtaining a first plurality of flow cell images corresponding to different fluorescent wavelengths, wherein the first plurality of flow cell images represents the flow cell in one or more flow cycles, and wherein each wavelength of the different fluorescent wavelengths corresponds to a respective nucleotide base;
identifying one or more DNA cluster centers in the first plurality of flow cell images by applying a spot-finding algorithm based on pixel intensity and relative color purity of the plurality of flow cell images, and
generating a template by mapping a plurality of base-calling locations corresponding to the identified one or more DNA cluster centers onto the template, wherein the template is configured for registering a second plurality of flow cell images acquired of the flow cell in one or more subsequent flow cycles to the template.
18. The non-transitory computer readable storage medium of claim 17 , wherein the spot-finding algorithm detects the one or more DNA cluster centers at a sub-pixel resolution.
19. The non-transitory computer readable storage medium of claim 17 , wherein a wavelength of an optical signal detected at the one or more DNA cluster centers in a flow cycle correlates to a nucleotide base added to the one or more DNA cluster centers in the flow cycle.
20. The non-transitory computer readable storage medium of claim 17 , wherein mapping the plurality of base-calling locations corresponding to the identified DNA cluster centers onto the template comprises generating coordinates of the plurality of base-calling locations in a common coordinate system.