R-D Cost Function and Coding Decisions
The R-D cost function (or RDO) where ‘b’ is the block under consideration, ‘d’ is the decision to be made, ‘C’ is the cost to minimize, ‘D’ is the distortion if the decision ‘d’ is taken, ‘R’ is the corresponding change in bitrate, while λ is an application-dependent Lagrangian weighting factor expressing how much bits […]
Best Lossless Compression Rate of English Text on Average
Number of English letters (incl. capital ones), punctuation symbols is less 128, hence you need 7-bits per English text symbol. The calculated entropy of the English language is 2.62 bits per letter on average. According to Shannon’s Source Coding Theorem the best compression ratio you can obtain without distorting the original text (i.e. by lossless […]
Exercise in Combinatorics for Team Leader
Let’s imagine you are a team leader (for me it’s really difficult, i’ve never been a manager). Your team consists of 5 different engineers (if you are a good leader, you must see that the engineers are mutually different, otherwise you ought to resign). You just have obtained 10 different tasks to accomplish in a […]
The Cocktail Party Paradox
In Theory of Graphs there is the following theorem: A graph with more than two vertexes has at least two vertexes with the same degree. Proof Let’s consider a party where each guest is a vertex. Two vertexes (or guests) are connected if they are acquaintances. The theorem asserts that in each party above […]
MPEG-5 EVC Codec – Baseline Profile
Encoder Getting and Compilation (in Windows) Running MPEG-5 EVC encoder (xeveb_app.exe) Decoder Getting and Compilation of MPEG-5 Decoder (in Windows) Running MPEG-5 EVC Decoder Encoder MPEG-5 EVC is tailored for 8K encoding. Getting and Compilation (in Windows) Sources of MPEG-5 EVC encoder are free. It’s worth noticing that […]
Implementation of Anti-aliasing Filter in Downscaling
Introduction One of annoying distortions of down-scaling is aliasing impairments. It’s a common practice to apply an anti-aliasing filter prior to down-scaling process. Generally speaking the anti-aliasing filter is a low pass filter usually used before a signal sampler in order to reduce the signal frequency bandwidth and approximately to satisfy the Nyquist Sampling theorem. […]
Detection Anomalies (Outliers) in Data
Content Z-score Method Tukey’s Method Outlier Ratio Appendix: Coefficient of Variation (CV) Z-score method If data is distributed normally then we can use z-score method (or the three-sigma rule) to detect outliers (values exceeding 3 std deviations in both directions are considered as anomalies). The following python snippet demonstrates how to detect anomalies […]
Image Scaling
How Perform Scaling with ffmpeg Scaling with JSVM DownConvertStatic.exe There are many techniques to scale images, most popular are Nearest Neighbor, Bilinear, Bicubic, Spline, and Lanczos. The Nearest Neighbor considers the closest pixel, Bilinear – the closest 2×2 pixels, Bicubic the closest 4 × 4 pixels. Spline and Lanczos consider more surrounding pixels. If we […]
Visually Lossless Noise Injector
Abstract The purpose of this post is to describe injection of visually lossless noise. The injector generates invisible noise, i.e. under Human Eye detection threshold (or in other words under JND – just noticeable difference). Currently JND calculation is based on luminance masking (TBD – texture masking and temporal masking). For details on Human Vision […]
Evaluation of cutree mode in x265
Introduction The idea of CTU-tree (cutree mode) is as follows: a block is more important if it is referenced by many other blocks, i.e. has many ancestors in the graph (or in the tree). cutree makes sense if the lookahead is enabled, otherwise we can’t know ahead how much a given block is referenced in […]