Systems and methods for medical imaging using a rolling shutter imager
A method of imaging tissue of a subject using an electronic rolling shutter imager includes sequentially resetting rows of pixels of the rolling shutter imager from a first row to a last row for a first amount of time; illuminating the tissue of the subject with illumination light over an illumination period that begins once the last row of the rolling shutter imager has been reset and lasts for at least the first amount of time; accumulating charge at the rows of pixels over at least the illumination period based on light that is received from the tissue of the subject while the tissue of the subject is illuminated with the illumination light; sequentially reading charge accumulated at the rows of pixels from the first row to the last row once the illumination period has ended; and generating an image frame from the rows of pixels.
1. A method of imaging tissue of a subject using an electronic rolling shutter imager, the method comprising:
sequentially resetting rows of pixels of the rolling shutter imager from a first row to a last row, wherein the sequential resetting from the first row to the last row lasts a first amount of time;
illuminating the tissue of the subject with illumination light over an illumination period that begins once the last row of the rolling shutter imager has been reset and lasts for at least the first amount of time;
accumulating charge at the rows of pixels over at least the illumination period based on light that is received from the tissue of the subject while the tissue of the subject is illuminated with the illumination light;
sequentially reading charge accumulated at the rows of pixels from the first row to the last row once the illumination period has ended; and
generating an image frame from the readings of charge accumulated at the rows of pixels.
2. The method of claim 1 , wherein illuminating the tissue of the subject with illumination light comprises pulsing the illumination light.
3. The method of claim 1 , further comprising controlling a pulse width of the pulsed illumination light based on readings of charge accumulated at the rows of pixels during a previous frame.
4. The method of claim 1 , wherein each row of pixels accumulates charge over the illumination period.
5. The method of claim 1 , wherein each row of pixels accumulates charge for at least twice the first amount of time.
6. The method of claim 1 , wherein the illumination light is generated by at least one LED.
7. The method of claim 1 , wherein the rolling shutter imager is part of an endoscopic imager.
8. The method of claim 1 , wherein the rolling shutter imager comprises a mechanical shutter and the mechanical shutter remains at least partially open from before the illumination begins until after the illumination period ends.
9. The method of claim 8 , further comprising reducing an amount of light received at the rolling shutter imager by operating the mechanical shutter.
10. The method of claim 1 , further comprising adjusting a gain of the rolling shutter imager based on readings of charge accumulated at the rows of pixels during a previous frame.
11. A system for imaging tissue of a subject, the system comprising:
an illumination source; and
an imaging apparatus that comprises an electronic rolling shutter imager, the imaging apparatus being configured for:
sequentially resetting rows of pixels of the rolling shutter imager from a first row to a last row, wherein the sequential resetting from the first row to the last row lasts a first amount of time,
controlling the illumination source to illuminate the tissue of the subject with illumination light over an illumination period that begins once the last row of the rolling shutter imager has been reset and lasts for at least the first amount of time,
accumulating charge at the rows of pixels over at least the illumination period based on light that is received from the tissue of the subject while the tissue of the subject is illuminated with the illumination light,
sequentially reading charge accumulated at the rows of pixels from the first row to the last row once the illumination period has ended, and
generating an image frame from the readings of charge accumulated at the rows of pixels.
12. The system of claim 11 , wherein the imaging apparatus comprises a camera control unit connected to an imaging head that includes the rolling shutter imager.
13. The system of claim 12 , wherein the illumination source is configured for pulse width modulated illumination and the camera control unit generates a pulse width modulation waveform for controlling the illumination source.