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One of several improvements made to the word spotter was to use faster descriptor based on a few elements of the Fourier transform of radial lines with logarithmic sampling. This makes the descriptor much faster, but still robust enough. Actually, it must not be too precise as the shape of the words varies in the text. … Continue reading The Radial Line Fourier Descriptor

Since documents often are somewhat degraded it is important to be able to efficiently remove the disturbing background from the text. The next step would be to binarise the segmented text, but in our wordspotter we prefer to work on the background removed text. We have published two papers dealing with these problems. Automatic Document … Continue reading Background Removal and Binarisation

We developed a segmentation free word spotter, which means that each word do not have to be extracted from the text. Instead a sliding window (cyan box) is used to traverse the document.  Key point matching was performed on four sets of different key points, using a descriptor based on the Fourier transform followed by … Continue reading Segmentation-free Word Spotting

It is quite a challenging task to make a prefect bounding box for a word by hand. This paper deals with this problem, but the algorithm can also be used in the word spotter for finding a perfectly fitting box of the found word. The image shows how the user has marked the red box, … Continue reading User Annotation and Bounding Text Boxes

The idea proposed in this paper is to use a log polar sampling scheme followed by a FFT in order to obtain a rotation and to some degree scale invariant feature descriptor. The feature vector will be rather short since just the most discriminative part of the FFT is used. A short feature vector for … Continue reading The Log-Polar Magnitude Feature Descriptor