Free predictor software for linux

Visual difference metrics can predict whether differences between two images are visible to the human observer or not. Such metrics are used for testing either visibility of information (whether we can see important visual information) or visibility of noise (to make sure we do not see any distortions in images, e.g. due to lossy compression).

The image below shows how two input images, a reference image (upper left) and a distorted image (lower left), are processed with the VDP to produce a probability of detection map (right). Such probability of detection map tells how likely we will notice a difference between two images for each part of an image.

Red color denotes high probability, green - low probability. Red color is mostly present in the areas where there is a snow covered path. Because of smooth texture of the snow, there is not much visual masking and distortions are easily visible.

Although there are dozens of visible difference metrics that serve a similar purpose, our Visual Difference Predictor for HDR images (HDR-VDP) has two unique advantages: firstly, our metric works with a full range of luminance values that can be meet in a real word (HDR images), and secondly, we offer a complete source code for free.

High Dynamic Range Visible Difference Predictor (HDR-VDP) can work within the complete range of luminance the human eye can see. An input to our metric is a high dynamic range (HDR) image, or an ordinary 8-bits-per-color image, converted to the actual luminance values. The proposed metric takes into account the aspects of high contrast vision, like scattering of the light in the optics (OTF), nonlinear response to light for the full range of luminance, and local adaptation.

OptimFROG is a lossless audio compression program. OptimFROG project main goal is to reduce at maximum the size of audio files, while premitting bit identical restoration for all input. It is similar with the ZIP compression, but it is highly specialized to compress audio data.
OptimFROG obtains asymptotically the best lossless audio compression ratios. It has Windows and Linux versions, fully featured input plug-ins for the foobar2000, Winamp2, Winamp3, dBpowerAMP, XMPlay and XMMS audio players (with bitstream error resilience, ID3v1.1 and APEv2 read tagging support), optimal support for all integer PCM wave formats up to 32 bits and an extensible streamable (error tolerant) compressed format. It is also fast, the default mode encodes CD quality audio data at 12.4x real-time and decodes at 17.4x real-time on AMD Athlon XP 1800+ (the fastest mode encodes at 28.1x real-time and decodes at 24.7x real-time).
The compression ratios which can obtained with OptimFROG are generally ranging from 25% (silent classical music) to 70% (loud rock music) of the original audio file size. This is less compared with around 13% obtained with high quality MP3 files (~176 kb), but you have the great advantage of archiving and listening at perfect copies of your original music.
OptimFROG uses a new audio compression technology, the generalized stereo decorrelation concept (together with the optimal predictor), which was first introduced with OptimFROG 4.0b in December 2001. At the time of its introduction, the new technology yielded significant better (~1.5%) compression than existing state of the art lossless audio compressors.
Main features:
- asymptotically the best lossless audio compression ratios
- optimal support for all integer PCM wave formats up to 32 bits
- fully featured foobar2000, dBpowerAMP, Winamp2, Winamp3, XMPlay, and XMMS input plug-ins for playback
- fast operation, default mode encodes CD quality audio data at 12.4x real-time and decodes at 17.4x real-time on AMD Athlon XP 1800+
- Win32 and Linux command line versions
- simple to use, but powerful Windows GUI front-end, Kermit (made by Speek)
- extensible, streamable compressed format, tagging compatible
- optimize option, further improving compression at no decoding cost
- backward compatible with version 4.2x (decode only)
- 64 bits large file support under Win32
- full pipe support for encoding and decoding
- full raw file support
- quick verify compressed file integrity function
- compatible with Exact Audio Copy, with ID3v1.1 tagging
- extensible command line format
- multiple file processing on the same command line, with wildcards
- option to store MD5 of raw PCM input data and function to check it
- option to delete source file after successful operation
- option to copy source file time stamp to destination file
- bitstream error resilience and transparent real-time recovery
- fast seek with intelligent caching for plug-ins
- ID3v1.1 and APEv2 read tagging support for plug-ins
- streaming support (playing HTTP streams) for foobar2000 plug-in
- Replay Gain compatible plug-ins for foobar2000 and Winamp3
- fully featured SDK for using compressed files in any application