  The demand for on-device document recognition systems increases in
conjunction with the emergence of more strict privacy and security
requirements. In such systems, there is no data transfer from the end device to
a third-party information processing servers. The response time is vital to the
user experience of on-device document recognition. Combined with the
unavailability of discrete GPUs, powerful CPUs, or a large RAM capacity on
consumer-grade end devices such as smartphones, the time limitations put
significant constraints on the computational complexity of the applied
algorithms for on-device execution.
  In this work, we consider document location in an image without prior
knowledge of the document content or its internal structure. In accordance with
the published works, at least 5 systems offer solutions for on-device document
location. All these systems use a location method which can be considered
Hough-based. The precision of such systems seems to be lower than that of the
state-of-the-art solutions which were not designed to account for the limited
computational resources.
  We propose an advanced Hough-based method. In contrast with other approaches,
it accounts for the geometric invariants of the central projection model and
combines both edge and color features for document boundary detection. The
proposed method allowed for the second best result for SmartDoc dataset in
terms of precision, surpassed by U-net like neural network. When evaluated on a
more challenging MIDV-500 dataset, the proposed algorithm guaranteed the best
precision compared to published methods. Our method retained the applicability
to on-device computations.
