Leszek Swierkowski

A video geo-location and image enhancement tool for small unmanned air vehicles (UAVs)

This paper describes recent work conducted in collaboration with DSTO Australia and Aerosonde to develop video-based geolocation (targeting) and real-time enhancement of ground features observed from a small unmanned air vehicle (UAV). Here a combination of low-cost GPS, video and attitude sensors are used to estimate the object ground position whilst a simple super-resolution technique is used to enhance images of the object of interest. The results of two recent trials of the developed algorithms are presented.

Resistor array infrared projector nonuniformity correction: search for performance improvement III

Results from sparse grid and flood nonuniformity correction (NUC) obtained using the DSTO Primary Infrared Scene Projection at 1:1 mapping ratio are reported. Residual nonuniformities in the 0.5-1.0% range are currently being achieved, the flood results equating to noise equivalent temperature differences in the 50-100mK range within the low drive thermal imager and FLIR simulation region. The NUC techniques and results are discussed in the light of both their present applicability and scope for further improvement.

Search for optimal infrared projector nonuniformity correction procedures

A search is commenced directed towards understanding the fundamental elements that underlie the generation of nonuniformity correction information in dynamic infrared scene projection systems.

Emissive infrared projector sparse grid nonuniformity correction

Results from application of the sparse grid nonuniformity correction procedure within the DSTO resistor array Primary Infrared Scene Projection system are reported. In particular, the techniques used to cover the full dynamic range and to combat camera drift are described. The effectiveness of the projector NUC procedure is assessed and discussed in terms of the scope for further improvement.

An Iterative Approach to Image Super-Resolution

Undersampling and aliasing occurs frequently in many imaging systems leading to degradation of image quality. Super-resolution attempts to reconstruct a high-resolution image by fusing the incomplete scene information contained in the sequence of under-sampled images. This paper investigates iterative approaches to super-resolution. We propose algorithm that utilises a relatively small number of low-resolution images and is computationally inexpensive. Experimental results of reconstruction are presented.

Fast Iterative Super-Resolution for Image Sequences

Images are often degraded by undersampling and aliasing that occurs in many imaging systems. Super- resolution reconstructs a high-resolution image from a sequence of observed low-resolution images. This paper presents a mathematical justification of the IISR reconstruction algorithm formulated in [1] on intuitive grounds. It is then shown that by combining the IISR method with a regularized optimization approach to super-resolution, the reconstruction process can be improved. Numerical results for reconstruction are presented.

Infrared projector flood nonuniformity correction characteristics

The DSTO Primary Infrared Scene Projection (PIRSP) system has been used to investigate the practical application of the emitter array flood nonuniformity correction (NUC) technique. In the first instance the measurements have been limited to the special case of unity mapping ratio. The methods for achieving unity mapping at sub-pixel registration are described; in particular, the use of Moire fringes for accurately measuring the optical distortion across the field-of-view and for attaining the optimal mapping condition. Application of the flood NUC technique within the PIRSP system is discussed in terms of its convergence limitations. The latter include the presence of spatial and temporal camera noise, optical distortion, the mixing of neighbouring pixel information due to the finite point spread function and radiance-to-voltage transformation errors.

Infrared projector scene data real-time processor design

A new infrared projector emitter response curve-fitting procedure suitable for generating nonuniformity coefficients capable of being applied in existing real-time processing architectures is introduced. The procedure has been developed through detailed analysis of a Honeywell Multi-Spectral Scene Projector (MSSP) sparse array data set, combined with an appreciation of the underlying physical processes that lead to the generation of infrared radiance.

Precise modulation transfer function measurements for focal plane array systems

This paper provides an improved method of measuring the modulation transfer function (MTF) in undersampled systems. We show that the currently used canted slit 2D FFT method is limited because interference between the aliased Fourier components and the side-peaks in the non-aliased signal significantly influences the MTF measurements at spatial frequencies larger than the Nyquist frequency. In our new approach, the effective temperature of the slit illumination varies along the slit, with the intensity profile chosen to minimize the interference between the aliased and non-aliased signal components. The accuracy of the measurement procedure has been improved to the point where the main limitation is the temporal and the fixed pattern noise of the IR camera. Experimental results confirming the accuracy at frequencies both below and above the Nyquist frequency are presented.

Advanced flood nonuniformity correction for emitter array infrared projectors

The search for optimal IR scene projection nonuniformity correction procedures reported in earlier papers is continued. In this paper the application of the flood nonuniformity correction procedure described earlier is extended to the case where only a sublattice of projector pixels is lit, enabling nonuniformity correction for the practically interesting case of greater-than-unity mapping ratios.