Fixed-point math in time-critical C applications

Kraeling, Mark

doi:10.1109/wescon.1996.554588

Cited by 3 publications

(1 citation statement)

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“…Since floating point operations are known to be computationally costly on standard PCs, we have implemented the same forward differencing technique using fixed point representation given enough padding for any overflow caused from accumulation operations. (For a description of the use of fixed point representation, see Kraeling, 1996). Floating point numbers such as the coefficients in Eqs.…”

Section: Real Time Image Alignmentmentioning

confidence: 99%

High speed method for in situ multispectral image registration

Perrine

LaMarche

Hopkins

et al. 2007

Microscopy Res & Technique

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High speed data registration is required for the study of fluorescence resonance energy transfer in real time as well as fast dynamic intra- and inter-cellular signaling events. Multispectral confocal spinning disk microscopy provides a high resolution method for performing such real time live cell imaging. However, optical distortions and the physical misalignments introduced by the use of multiple acquisition cameras can obscure spatial information contained in the captured images. In this manuscript, we describe a multispectral method for real time image registration whereby the image from one camera is warped onto the image from a second camera via a polynomial correction. This method provides a real time pixel-for-pixel match between images obtained over physically distinct optical paths. Using an in situ calibration method, the polynomial is characterized by a set of coefficients, using a least squares solver. Error analysis demonstrates optimal performance results from the use of cubic polynomials. High-speed evaluation of the warp is then performed through forward differencing with fixed-point data types. Forward differencing is an iterative approach for evaluating polynomials on the condition that the function variable changes with constant steps. Image reconstruction errors are reduced through bilinear interpolation. The registration techniques described here allow for successful registration of multispectral images in real time (exceeding 15 frame/s) and have a broad applicability to imaging methods requiring pixel matching over multiple data channels.

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Section: Real Time Image Alignmentmentioning

confidence: 99%

High speed method for in situ multispectral image registration

Perrine

LaMarche

Hopkins

et al. 2007

Microscopy Res & Technique

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Software and Hardware co-design for MP3 Decoder

Yang

Huang

Hung

et al. 2006

TENCON 2006 - 2006 IEEE Region 10 Conference

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Improved Haptic Fidelity via Reduced Sampling Period With an FPGA-Based Real-Time Hardware Platform

Sevcik

Kopp²,

O’Malley

2007

Volume 9: Mechanical Systems and Control, Parts A, B, and C

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Impedance based haptic interfaces face inherent challenges in displaying stiff virtual environments. Fidelity of a virtual environment is enhanced by stiff virtual walls combined with low damping and passive behavior of the interface. However, the stiffness of virtual walls displayed on an impedance based interface is limited by the damping inherent in the controller, the sampling rate of the control loop, and the quantization of the controller’s position. Attempting to display a stiffness larger than this limiting value destroys the passivity of the interface, leading to active controller behavior and eventually closed loop instability. We propose a method of increasing the fidelity of a PHANToM Premium 1.0 commercial haptic interface by controlling it via a Field Programmable Gate Array (FPGA) both alone and with a Real Time Operating System (RTOS) control system. This custom controller enjoys several benefits over the standard control achieved via a proprietary control card in a Multitasking OS, including reduced system overhead and deterministic loop rate timing. The performance of the proposed FPGA/RTOS controller compares favorably with the performance of an FPGA/Multitasking OS controller. The FPGA/RTOS controller achieves control loop rates an order of magnitude greater than that of the proprietary controller, allowing virtual walls to be displayed with greatly increased stiffnesses, while retaining the passivity and low damping of the PHANToM interface.

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Fixed-point math in time-critical C applications

Cited by 3 publications

References 0 publications

High speed method for in situ multispectral image registration

High speed method for in situ multispectral image registration

Software and Hardware co-design for MP3 Decoder

Improved Haptic Fidelity via Reduced Sampling Period With an FPGA-Based Real-Time Hardware Platform

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