A Method for Coding a Sequence of Digital Images

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This invention describes a novel method for encoding (compressing) sequences of digital images, such as those in video, using a new intra-prediction approach. The method uses a Non-Local Means (NLM)-based algorithm to predict the value of each pixel by averaging values of similar surrounding pixel regions within the same image. The similarity between pixel neighborhoods is calculated, and more similar regions are weighted higher in the prediction. This approach aims to improve compression efficiency, reduce noise in predictions, and minimize computational complexity compared to prior art.

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• Video compression in consumer electronics (e.g., cameras, smartphones, webcams)
• Live video streaming over networks with limited bandwidth
• Archival storage of high-volume image or video datasets (e.g., surveillance, medical imaging, astronomy)
• Lossless and lossy compression for digital image transmission (e.g., telemedicine, satellite imaging)
• Integration into next-generation video coding standards (such as HEVC/H.265, or future standards)
• Efficient storage of professional content (e.g., broadcasting, audiovisual production)
• Real-time encoding/decoding in embedded systems and hardware codecs

BenefitsContent extracted from patent full text and abstract with AI.

• Improved compression efficiency with lower bitrates compared to classic prediction modes, saving bandwidth and storage without quality loss
• Capable of both lossless and lossy compression, increasing flexibility for various application needs
• Automatically reduces prediction noise thanks to weighted similarity, leading to better image quality
• Reduces computational complexity because no large systems of equations need to be solved (unlike least-squares methods)
• No need to transmit additional side information like weights, minimizing overhead in data transmission
• Backwards adaptive: prediction can be performed solely based on reconstructed (decoded) pixels, improving encoder/decoder synchronization
• Easily integrates with existing block or pixel-wise coders and current video coding standards

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Patent Abstract

The invention refers to a method for coding a sequence of digital images (I), wherein the method uses a number of prediction modes for predicting values of pixels (P1) in the images (I) based on reconstructed values of pixels in image areas processed previously, where a prediction error (PE) between predicted values and the original values of pixels (P1) is processed for generating the coded sequence of digital images (CI). The invention is characterized in that a preset prediction mode (NLM) is an intra-prediction mode based on pixels of a single image (I), in which preset prediction mode (NLM). In a step i), for a region (R) of pixels with reconstructed values in the single image (I) and for a template (TE) of an image area, a first patch (PA1) of pixels in the region (R) which surround a first pixel (P1) to be predicted based on the template (TE) is compared with several second patches (PA2), each second patch (PA2) being assigned to a second pixel (P2) in the region (R) and consisting of pixels in the region (R) which surround the second pixel (P2) based on the template (TE), thereby determining a similarity measure (SM) for each second pixel (P2) describing the similarity between reconstructed values of the pixels of the second patch (PA2) assigned to the respective second pixel (P2) and the reconstructed values of the pixels of the first patch (PA1). In a step ii), a predicted value of each first pixel (PI) is determined based on a weighted sum of values of the second pixels (P2), where the value of each second pixel (P2) is weighted by a weighting factor which is monotonously decreasing in dependency on a decreasing similarity described by the similarity measure (SM) for the respective second pixel (P2).