In order to make the CMOS image sensors suitable for space high resolution imaging applications, a new method realizing TDI in digital domain by FPGA is proposed in this paper, which improves the imaging mode for area array CMOS sensors. The TDI algorithm accumulates the corresponding pixels of adjoining frames in digital domain, so the gray values increase by M times, where M is for the integration number, and the image’s quality in signal-to-noise ratio can be improved. In addition, the TDI optimization algorithm is discussed. Firstly, the signal storage is optimized by 2 slices of external RAM, where memory depth expanding and the table tennis operation mechanism are used. Secondly, the FIFO operation mechanism reduces the reading and writing operation on memory by M×(M-1) times, It saves so much signal transfer time as is proportional to the square of integration number M2, that the frame frequency is able to increase greatly. At last, the CMOS camera based on TDI in digital domain is developed, and the algorithm is validated by experiments on it.
[1]
Hee Chul Lee,et al.
Smart CMOS Charge Transfer Readout Circuit for Time Delay and Integration Arrays
,
2006,
IEEE Custom Integrated Circuits Conference 2006.
[2]
G. Meynants,et al.
Time-Delay-Integration Architectures in CMOS Image Sensors
,
2009,
IEEE Transactions on Electron Devices.
[3]
Yuan Wang,et al.
A high efficient analog charge delay line for high performance CMOS readout integrated circuits with TDI function
,
2007,
2007 7th International Conference on ASIC.
[4]
Zhang Ye.
NextView program and progress in optical remote sensing satellites
,
2009
.
[5]
Nanjian Wu,et al.
A high-speed CMOS image sensor for real-time vision chip
,
2011
.
[6]
Wim Diels,et al.
CMOS long linear array for space application
,
2006,
Electronic Imaging.
[7]
Ernst Bodenstorfer,et al.
High-speed line-scan camera with digital time delay integration
,
2007,
Electronic Imaging.