Apple Inc.

Anders M Holtsberg

Martin Lindberg

Jianping Zhou

Rudolph Van Der Merwe

David Benjamin Millman

Jason Klivington

Sebastien X Beysserie

George E Williams

Jasvinder Singh

Darin Tay

Damien J Thivent

Xiaoxing Li

Brandon J Corey

Benjamin A Detwiler

Wuzhou Zhang

Embodiments are disclosed for compressing radio maps of fingerprint-based positioning systems using different compression models. In an embodiment, a method comprises: receiving, by a computing device, access point (AP) data from a plurality of mobile devices operating in a geographic region, the AP data including signal strength measurements of AP signals received at a plurality of reference locations in the geographic region and uncertainty measurements associated with the signal strength measurements; determining a level of accuracy with the first compression model; responsive to the determining, selecting one of the first compression model or a second compression model to compress the AP data, the second compression model being different than the first compression model; compressing the AP data using the selected compression model; and responsive to a request from a mobile device operating in the geographic region, sending a data packet including the compressed AP data to the mobile device.

Compressing radio maps using different compression models

Embodiments are disclosed for compressing radio maps of fingerprint-based positioning systems. In an embodiment, a method comprises: receiving access point (AP) data from a plurality of mobile devices operating in a geographic region, the AP data including signal strength measurements of AP signals received at a plurality of reference locations in the geographic region; filtering the AP data to remove outlier AP data; fitting a surface to the AP data; projecting AP data at surface control points onto a two-dimensional image grid; determining a boundary surrounding locations of the AP data at the surface control points; encoding the boundary; encoding the AP data at the surface control points included within the boundary; generating compressed radio maps from the encoded AP data; and responsive to a request from a mobile device operating in the geographic region, sending a data packet including the compressed radio maps to the mobile device.

Compressing radio maps

Techniques to permit a digital image capture device to stabilize a video stream in real-time (during video capture operations) are presented. In general, techniques are disclosed for stabilizing video images using an overscan region and a look-ahead technique enabled by buffering a number of video input frames before generating a first stabilized video output frame. (Capturing a larger image than is displayed creates a buffer of pixels around the edge of an image; overscan is the term given to this buffer of pixels.) More particularly, techniques are disclosed for buffering an initial number of input frames so that a 'current' frame can use motion data from both 'past' and &#x201c;future&#x201d; frames to adjust the strength of a stabilization metric value so as to keep the current frame within its overscan. This look-ahead and look-behind capability permits a smoother stabilizing regime with fewer abrupt adjustments.

Video image stabilization

An image is compressed according to a compression ratio selected based on a compression metric. In one embodiment, the compression metric is based on image characteristics indicative of the amount of image noise in an image, such as gain and lux. Greater compression ratios are used for image having compression metrics indicating a higher degree of noise. Because an image with higher image noise levels already has a reduced visual quality, the impact of higher compression is less significant as compared to the impact of compression on images having low image noise. In an embodiment, an image is divided into a number of regions, for each of which a compression metric and corresponding compression ratio is determined, so that regions of the image having high image noise may be compressed more than regions having low image noise.

Dynamic compression ratio selection

Growing community of inventors

Los Gatos, CA, United States of America

Anders M Holtsberg