Real-Time Processing for Logarithmic CMOS Image Sensors

• Author / Creator

  Li, Jing

• This thesis proposes a real-time DSP design for logarithmic CMOS image sensors. The design contains novel FPN correction and tone mapping methods suitable for fixed-point operation. Logarithmic CMOS image sensors offer high DR at video rate but suffer from nonlinear FPN. FPN, due to parameter variation across pixels, results in lower image quality. A new method based on the Taylor series is introduced to correct nonlinear FPN effectively and efficiently. After FPN correction of a high-DR scene, reproducing it for display is challenging. Subjective DR needs to be communicated to human observers while objective DR must be compressed to suit the DR of a standard display. A new method maps tones of high-DR scenes for standard displays while limiting the visibility of camera noise. The new FPN correction and tone mapping methods both exhibit low computational complexity, which make them ideal for real-time processing. A fixed-point design of the proposed DSP is developed to further reduce computational complexity, enabling lower power consumption. Although experiments were done with a standard logarithmic CMOS image sensor, the proposed methods may be applied to other nonlinear image sensors thanks to their inherent generality.

• Subjects / Keywords

  • Logarithmic image sensors
  • Tone mapping
  • CMOS
  • FPN correction
  • Real time

• Graduation date

  Spring 2012

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3542JH59

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.