Free histogram equalization software for linux

Equalize plug-in does a histogram equalization of the image.

That is, it modifies the images histogram so that it is approximately horizontal, so that all intensity values cover about the same number of pixels in the image (i.e. the histogram is well-balanced).

DigikamImagePlugins are a collection of plugins for digiKam 0.7.3 Image Editor and ShowFoto 0.2.0 (digiKam stand alone image editor implementation).
DigikamImagePlugins add new image treatment options like color management, filters or special effects.
Main features:
Image improvements:
- icon Adjust levels : a tool to adjust the photograph histogram levels manually.
- icon Adjust curves : a tool to adjust the photograph colors using curves.
- icon Noise Reduction : a photograph noise reduction filter.
- icon Unsharp : a photograph unsharp mask filter to unblur picture without increase noise.
- icon Lens Distortion : a tool for correct lens spherical aberration on photograph.
- icon Anti Vignetting : a tool for correct vignetting on photograph.
- icon Channel Mixer : a tool to mix the photograph color channels (CVS only).
- icon White Balance : a tool to adjust white color temperature balance of photograph (CVS only).
- icon Photograph Restoration : a tool to reduce photograph artefacts using CImg library (CVS only).
- icon Photograph Inpainting : a tool to remove unwanted photograph area using CImg library (CVS only).
Transformation tools:
- icon Free Rotation : a plugin to rotate a photograph with a free angle in degrees.
- icon Shear Tool : a plugin to shear a photograph horizontally and vertically.
- icon Perpective Tool : a plugin to adjust the photograph perpective.
- icon Blowup Photograph : a plugin to blowup a photograph without less image quality using CImg library (CVS only).
Image tools:
- icon Template Superimpose : a tool for superimpose a template on photograph.
- icon Add Border : a tool for add border around a photograph.
- icon Insert Text : a tool for insert text under a photograph (CVS only).
- icon Apply Texture : a tool to apply a decorative texture to a photograph (CVS only).
Special effects:
- icon Solarize : a plugin to solarize a photograph.
- icon Oil Paint : simulate oil painting on photograph (using Pieter Voloshyn algorithm).
- icon Emboss : an effect filter to emboss photograph (using Pieter Voloshyn algorithm).
- icon Rain Drops : adding the visual effect of raindrops on photograph (using Pieter Voloshyn algorithm).
- icon Charcoal : simulate charcoal drawing on photograph.
- icon FilmGrain : simulate film grain on photograph.
- icon Infrared : simulate infrared film effect on photograph (CVS only).
- icon Blur FX : apply bluring special effects on photograph (using Pieter Voloshyn algorithms - CVS only).
- icon Distortion FX : apply distortion special effects on photograph (using Pieter Voloshyn algorithms - CVS only).
Installation:
export WANT_AUTOCONF_2_5=1
export KDEDIR=KDE_installation_dir_on_your_system
make -f Makefile.cvs
./configure --enable-debug=full
make
su
make install

Diffstat reads the output of the diff command and displays a histogram of the insertions, deletions, and modifications in each file.
It is commonly used to provide a summary of the changes in large, complex patch files.
Enhancements:
- A bugfix to avoid modifying data that is being used by tsearch() for ordering the binary tree.

Baudline is a real-time signal analysis tool and an offline time-frequency browser. Baudline project has a built-in tone generation capability and it can play back audio files with a multitude of effects and filters.
Designed for environmental analysis missions that range from modulation parameter measurements to searching for transient signals that go bump in the night, baudline combines fast digital signal processing, versatile high-speed displays, and continuous capture tools for hunting down and studying elusive signal characteristics.
Main features:
- 192 kHz real-time bandwidth
- 96 dB dynamic range
- Real or Quadrature input
- Multiple sound card support
- Input Digital Down Converter (tuner)
- Configurable input channels that can perform various operations
- Channel Equalization
- Frequency, time, amplitude, and sample probability distribution analysis
- Drift Integration "de-chirping"
- High speed displays
- Test signal generation
Audio player
- looping
- speed control with multirate resampling
- pitch scaling
- heterodyning (frequency shifting)
- 2D matrix surround panning
- notch, high, and low pass filters
- digital gain boost
File loading
- file formats: .wav, .aiff, .au, .al, .snd, .voc, .rmd, .pvf, .mp3, ID3, .ogg, .gsm, .sah, .fna, raw, .avi, .mov
- channels: mono, stereo, ... up to 9 channels
- data formats: ASCII decimal, A-law, u-law, 1-bit (msb & lsb), 8-bit (signed & unsigned), 16/24/32-bit integer (little & big endian), float, double
- compression
- lossless suffixes: .gz, .bz2, .Z, .zip, .flac
- codecs: ADPCM, GSM, MPEG, Ogg Vorbis
Measurements
- peaks: primary, secondary, delta (Hz dB PSD)
- fundamental: (Hz dB PSD), auto drift rate, chromatic, periodicity, RPM
- distortion: SNR, THD, SINAD, ENOB, SFDR
- power: full, select, noise ratio (dB PSD)
- system: clips, delta selected, frequency range, cursor time, UTC time

graph-tool project is a program to help with statistical analysis of graphs.
Main features:
- support for directed and undirected graphs
- support for arbitrary vertex or edge properties
- generic filtering of edges and vertices
- several statistical measurements:
- degree (or scalar property) histogram
- vertex-vertex degree (or scalar property) correlation
- average nearest neighbours degree (or scalar property)
- vertex-edge-vertex correlation
- clustering coefficients
- assortativity coefficient
- average distance
- component statistics
- generation of random graphs with arbitrary degree distribution and degree correlation
- graph history measurement based on filtering
- support for graphml and dot file formats
The core algorithms are written in C++, making use of the Boost Graph Library, and template metaprogramming techniques, with performace in mind. The command line interface and other outlying code are written in python.

PAPI aims to provide the tool designer and application engineer with a consistent interface and methodology for use of the performance counter hardware found in most major microprocessors.
PAPI enables software engineers to see, in near real time, the relation between software performance and processor events.
The Performance API (PAPI) project specifies a standard application programming interface (API) for accessing hardware performance counters available on most modern microprocessors.
These counters exist as a small set of registers that count Events, occurrences of specific signals related to the processors function. Monitoring these events facilitates correlation between the structure of source/object code and the efficiency of the mapping of that code to the underlying architecture.
This correlation has a variety of uses in performance analysis including hand tuning, compiler optimization, debugging, benchmarking, monitoring and performance modeling. In addition, it is hoped that this information will prove useful in the development of new compilation technology as well as in steering architectural development towards alleviating commonly occurring bottlenecks in high performance computing.
PAPI provides two interfaces to the underlying counter hardware; a simple, high level interface for the acquisition of simple measurements and a fully programmable, low level interface directed towards users with more sophisticated needs.
The low level PAPI interface deals with hardware events in groups called EventSets. EventSets reflect how the counters are most frequently used, such as taking simultaneous measurements of different hardware events and relating them to one another.
For example, relating cycles to memory references or flops to level 1 cache misses can indicate poor locality and memory management. In addition, EventSets allow a highly efficient implementation which translates to more detailed and accurate measurements.
EventSets are fully programmable and have features such as guaranteed thread safety, writing of counter values, multiplexing and notification on threshold crossing, as well as processor specific features. The high level interface simply provides the ability to start, stop and read specific events, one at a time.
PAPI provides portability across different platforms. It uses the same routines with similar argument lists to control and access the counters for every architecture. As part of PAPI, we have predefined a set of events that we feel represents the lowest common denominator of every good counter implementation.
Our intent is that the same source code will count similar and possibly comparable events when run on different platforms. If the programmer chooses to use this set of standardized events, then the source code need not be changed and only a fresh compilation and link is necessary. However, should the developer wish to access machine specific events, the low level API provides access to all available events and counting modes.
If an event or feature does not exist on the current platform, PAPI returns an appropriate error code. This significantly reduces the porting effort of code using PAPI because the semantics of each call to PAPI remains the same, just the argument lists need updating. In addition to the standard set, each PAPI implementation supports all native events through the ability to directly accept platform specific counter numbers. Definitions for most, if not all of these, are included as conditional macros in the header file. In this way, PAPI avoids having inefficient code to translate all events for all platforms into a uniform representation and back again.
This translation is only done for the relatively few events defined in the standardized set. Some processors like those in the POWER series have counter groups. They enable access to specific groups of counters, instead of individual events. This presents a serious portability problem, thus PAPI abstracts hardware counters from their groups with a packed naming scheme. Each counter control value or event is made up of the counter group number and the number of the specific counter in that group.
PAPI can be divided into two layers of software. The upper layer consists of the API and machine independent support functions. The lower layer defines and exports a machine independent interface to machine dependent functions and data structures. These functions access the substrate, which may consist of the operating system, a kernel extension or assembly functions to directly access the processors registers.
PAPI tries to use the most efficient and flexible of the three, depending on what is available. Naturally, the functionality of the upper layers heavily depends on that provided by the substrate. In cases where the substrates do not provide highly desirable features, PAPI attempts to emulate them as described below.
PAPI makes sure the underlying operating system or library guards against overflow of counter values.
Each counter can potentially be incremented multiple times in a single clock cycle. This combined with increasing clock speeds and the small precision of some of the physical counters means that overflow is likely to occur.
One of the more advanced features of PAPI is to provide a portable implementation of asynchronous notification when counters exceed a user specified value.
This functionality provides the basis for PAPIs SVR4 compatible profiling calls, that generate an accurate histogram of performance interrupts based on hardware metrics, not on time. Such functionality provides the basis for all line level performance analysis software, from the antiquated days of AT&Ts prof to SGIs SpeedShop. Thus for any architecture with even the most rudimentary access to hardware performance counters, PAPI provides the foundation for a truly portable, source level, performance analysis tool based on real processor statistics.
Enhancements:
- The API was extended to decouple abstraction layers from hardware support and to provide initial support for different types of performance counters.

SANE Frontends project contains frontends to SANE ("Scanner Access Now Easy"), including xscanimage, xcam, and scanadf. Xscanimage is a GTK-based application for scanning images that can also be used as a GIMP-plugin.
Xcam is used to get images from cameras supported by SANE. Scanadf is a command line frontend especially suited for scanners equipped with automatic document feeders (ADF).
Here are some of the frontends included in the package:
- XSane - improved graphical frontend for scanners:
- improved enhancement functions (gamma handling)
- histogram
- stand-alone mode:
o scan and save utility (file formats: jpeg, png, pnm, ps, raw, tiff)
o scan and view
o copy utility
o fax utility
o email utility
- GIMP plug-in
- supported platforms:
o Unix (Linux, IRIX, AIX, ...)
o OS/2 version with X11
o Windows 9x/NT/2000 network scanning version
- QuiteInsane - Graphical frontend based on Qt 2.2.x
- Kooka - KDE frontend for sane
- xscanimage - graphical frontend for scanners (included in sane-frontends):
- stand-alone-version (scan and save utility, file format: pnm)
- as GIMP plug-in
- scanlite - free beta version of a Java frontend using josi
- FlScan - graphical frontend based on FLTK
- OpenOffice.org includes a simple scan interface that uses SANE.
Enhancements:
- bug fixes

Caliph & Emir are MPEG-7 based Java prototypes for digital photo and image annotation and retrieval supporting graph like annotation for semantic metadata and content based image retrieval using MPEG-7 descriptors.
Main features:
Features of Caliph:
- Extraction of IPTC and EXIF metadata and conversion to MPEG-7
- Extraction of following content based image retrieval descriptors:
- ColorLayout (measures color distribution in an image)
- ScalableColor (basically a color histogram)
- EdgeHistogram (measures edginess)
- Annotation of images with
- Free text metadata
- Quality rating
- Structured text metadata
- Meta2 data (metadata about metadata)
- Semantic Annotations
- Based on a editable catalogue for reusable semantic objects (like specific persons, places, ...)
- Fully visual & graphical user interface
- Automatic placement and layout of visual descriptions
- Export of semantic descriptions to Structured Text Descriptions
- Load and save annotations as MPEG-7 XML file
Features of Emir:
- Retrieval of annotations using the file system
- with XPath queries
- with keyword queries
- with quality constraints
- with example images for content based image retrieval
- Retrieval of Annotations using a Lucene index
- with inbuilt index creation
- using different fields for structured retrieval
- Retrieval of semantic graphs based on a Lucene powered index
- supporting wildcards for relations and nodes
- based on query expansion
- graphical query editor
- 2D data repository visualization based on the FastMap algorithm
- for image content descriptors ColorLayout, ScalableColor and EdgeHistogram
- for graphs based on the minimum common sub graph metric
Enhancements:
- This is mainly a maintenance release: Scalable Color descriptor extraction was fixed, and yields the same results as the MPEG-7 reference software.
- EdgeHistogramImpl has been updated.
- The DominantColor class was adapted.
- PPM and BMP images are now supported.
- Note that Java 6.0 is required for the binary version and 1.5 for compilation.