Expedient encoding system
An encoding system for an iris recognition system. In particular, it presents a robust encoding method of the iris textures to compress the iris pixel information into few bits that constitute the iris barcode to be stored or matched against database templates of same form. The iris encoding system is relied on to extract key bits of information under various conditions of capture, such as illumination, obscuration or eye illuminations variations.
1. A method for obtaining an image of an iris and encoding pixel information contained within the image, comprising a surveillance system to perform:
capturing an image of an iris with a digital camera;
employing an iris recognition system to segment the captured image, wherein segmentation isolates an annular iris from the remainder of the captured image;
employing the recognition system to extract from the segmented image of iris intensity vectors of the image at each of several angles,
applying a periodic filter to the intensity vectors by employing the recognition system to apply a periodic filter to the intensity vectors thereby encoding the filtered intensity vectors;
representing the encoding of the filtered intensity vectors as a barcode; and
storing the representation of the barcode in a non-transient storage medium.
2. The iris encoding method of claim 1 , wherein the periodic filter is constructed with a symmetric waveform.
3. The iris encoding method of claim 2 , wherein the symmetric waveform sums to zero over its period.
4. The iris encoding method of claim 1 , wherein each feature vector may be sign quantized with a one, zero, or unknown.
5. The iris encoding method of claim 1 , wherein the feature vector from the iris image at each of several angles is encoded into fewer bits to be used for matching.
6. The iris encoding method of claim 1 , wherein the feature vector from the iris image at each of several angles is encoded in stages into fewer bits to be used for matching.
7. The iris encoding method as claimed in any preceding claim, wherein extracting the encoding step is integrated with segmenting the image.