Abstract: A value is computed for a feature in an instance of query content and compared to a threshold value. Based on the comparison, first and second bits in a hash value, which is derived from the query content feature, are determined. Conditional probability values are computed for the likelihood that quantized values of the first and the second bits equal corresponding quantized bit values of a target or reference feature value. The conditional probabilities are compared and a relative strength determined for the first and second bits, which directly corresponds to the conditional probability. The bit with the lowest bit strength is selected as the weakbit. The value of the weakbit is toggled to generate a variation of the query hash value. The query may be extended using the query hash value variation.

Abstract: Visually imperceptible distortion, from watermarking or compression, desired for embedding into frames of a video sequence is computed. Within each spatiotemporal region of the frames, points are counted, which have feature information amplitude that at least equals the desired distortion. In each region, a fraction of the points with magnitudes at least equal to desired distortion is determined, in relation to the total number of points and compared to a threshold. Regions with fractions at least equal to the threshold are identified. Visual aspects of features in the identified regions are analyzed for salience related to drawing visual attention. The salience is compared to a threshold. Identified regions that do not exceed the salience threshold may be selected as candidates for hiding the watermark. Spatial and temporal contrast values may relate to the salience, as well as luminance values computed therewith.