43,735 research outputs found
Localization Recall Precision (LRP): A New Performance Metric for Object Detection
Average precision (AP), the area under the recall-precision (RP) curve, is
the standard performance measure for object detection. Despite its wide
acceptance, it has a number of shortcomings, the most important of which are
(i) the inability to distinguish very different RP curves, and (ii) the lack of
directly measuring bounding box localization accuracy. In this paper, we
propose 'Localization Recall Precision (LRP) Error', a new metric which we
specifically designed for object detection. LRP Error is composed of three
components related to localization, false negative (FN) rate and false positive
(FP) rate. Based on LRP, we introduce the 'Optimal LRP', the minimum achievable
LRP error representing the best achievable configuration of the detector in
terms of recall-precision and the tightness of the boxes. In contrast to AP,
which considers precisions over the entire recall domain, Optimal LRP
determines the 'best' confidence score threshold for a class, which balances
the trade-off between localization and recall-precision. In our experiments, we
show that, for state-of-the-art object (SOTA) detectors, Optimal LRP provides
richer and more discriminative information than AP. We also demonstrate that
the best confidence score thresholds vary significantly among classes and
detectors. Moreover, we present LRP results of a simple online video object
detector which uses a SOTA still image object detector and show that the
class-specific optimized thresholds increase the accuracy against the common
approach of using a general threshold for all classes. At
https://github.com/cancam/LRP we provide the source code that can compute LRP
for the PASCAL VOC and MSCOCO datasets. Our source code can easily be adapted
to other datasets as well.Comment: to appear in ECCV 201
Phase Retrieval From Binary Measurements
We consider the problem of signal reconstruction from quadratic measurements
that are encoded as +1 or -1 depending on whether they exceed a predetermined
positive threshold or not. Binary measurements are fast to acquire and
inexpensive in terms of hardware. We formulate the problem of signal
reconstruction using a consistency criterion, wherein one seeks to find a
signal that is in agreement with the measurements. To enforce consistency, we
construct a convex cost using a one-sided quadratic penalty and minimize it
using an iterative accelerated projected gradient-descent (APGD) technique. The
PGD scheme reduces the cost function in each iteration, whereas incorporating
momentum into PGD, notwithstanding the lack of such a descent property,
exhibits faster convergence than PGD empirically. We refer to the resulting
algorithm as binary phase retrieval (BPR). Considering additive white noise
contamination prior to quantization, we also derive the Cramer-Rao Bound (CRB)
for the binary encoding model. Experimental results demonstrate that the BPR
algorithm yields a signal-to- reconstruction error ratio (SRER) of
approximately 25 dB in the absence of noise. In the presence of noise prior to
quantization, the SRER is within 2 to 3 dB of the CRB
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