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Improved method for passive ranging based on surface estimation of an airborne object using an infrared image sensor

Mikluc D. L., Andric M. S., Mitrovic S. T., Bondzulic B. P.

Optica Applicata

2017

Vol. 47, nr 3

383--394

A new method for passive ranging using image size measurements from one sensor has been presented. The method relies on pixel filtration with histogram-based thresholding, followed by intensity and gradient magnitude analysis. Its efficiency and robustness were assessed in real infrared surveillance sequences, and it has proved to lead to better results than non-filtering techniques. The object distance estimation mean relative error does not exceed 3%, which implies that the suggested method enables precise range estimation based on object size measurements. To maximize the benefits of the suggested method, Kalman filter has been included in the algorithm in order to overcome fluctuations of the estimated object size.

Visual attention pooling and understanding the structural similarity index in multi-scale analysis

Bondzulic B. P., Petrovic V. S., Mitrovic S. T., Pavlovic B. Z., Andric M. S.

Optica Applicata

2014

Vol. 44, nr 2

267--283

We present a novel spatial pooling strategy and the results of an extensive multi-scale analysis of the well-known structural similarity index metric (SSIM) for objective image quality evaluation. We show, in contrast with some previous studies, that even relatively simple perceptual importance pooling strategies can significantly improve objective metric performance evaluated as the correlation with subjective quality assessment. In particular, we define an attention and quality driven pooling mechanism that focuses structural comparisons within the SSIM model to only those pixels exhibiting significant structural degradations. We show that optimal objective metric performance is achieved over very sparse spatial domains indeed that ignore most of the signal data. We also investigate an explicit breakdown of the structural models within SSIM and show that in combination with the proposed attention and quality driven pooling some of these models represent well performing metrics in their own right, when applied at appropriate scale for which there may not be a single optimal value. Our experiments demonstrate that the augmented SSIM metric using the proposed pooling model provides performance advantage on an extensive LIVE dataset covering hundreds of degraded images and 5 different distortion types compared to both conventional SSIM and state-of-the-art objective quality metrics.