The BCIF lossless image compression program
Contents
1. Java applet to embed BCIF images in a website The Java implementation of the BCIF algorithm allows the embedding of BCIF images in websites In this way losslessly highly compressed images can be inserted in a website even with no client side compatibility apart from Java installed When the user loads the page containing the BCIF image the Java applet will decompress it client side and show it in the web page When the first image is found the browser mat require some time to load Java for the following images the visualization should be quite fast You may need some basic notions about HTML and the use of Java applets to insert the images in a site Both the bcifGUI jar and bcif jar files contain the applet implemented in the class bcif bcifapplet class The required parameters are e Image the image name on the server eventually relative to the path of the current page Note that for the browser s security policy it is impossible to load images externally to the website where the HTML page is hosted e Width height the width and the height of the image The following example visualizes the image lena bcif size 512x512 pixels as suming that both the image and the bcifGUL jar files are in the same folder of the webpage lt applet codebase archive bcifGUI jar code bcif bcifapplet class width 512 height 512 gt lt param name image value lena bcif gt lt param name width value 512 gt lt param2. name height value 512 gt lt applet gt Of all of the modules of BCIF the applet is probably the least tested and the less responsive in case of error Another issue it is very unlikely that an user will be able to save the images on his local drive since the link to the image is not in a standard img tag but it is specified as an applet parameter The native executable command line utility The native executable command line utility has been implemented in C in order to obtain the maximum speed allowed by the BCIF algorithm Actually only a native executable for windows is furnished but soon the source code will be released allowing the compilation and execution of BCIF on any platform The syntax is the following bcif inputfile cl d outputfile h The c and d options specify the action to execute compress or decompress respectively The input file must be a BMP file to be compressed or a BCIF file to be decompressed if the output file is not specified a default filename is created by changing the extension of the inputfile to an appropriate one for the output format As in the Java version output files are overwritten without prompting so use with care Finally a h option is available to print some help About The BCIF algorithm has been created and implemented by Stefano Brocchi as an evolution of the older PCIF algorithm The first translation of the program in C comprehensive of a first optimization
3. The BCIF lossless image compression program User manual version 1 0 beta Stefano Brocchi December 8 2010 Contents The BCIF algorithm Readable formas co 6 eA ee SE a we eo a ek a e NO h The Java implementation Encoding and decoding high resolution images memory issues The Java GUT e ccs sas weg who howe amp bw me ape ce page a a The Java viewer and command line utility 0 orww Nn Using the Java applet to embed BCIF images in a website The native executable command line utility 5 About 6 The BCIF algorithm The BCIF algorithm is a image compression method that allows to encode an image without any loss of quality lossless It is designed to be a fast algorithm in order to allow practical usage its compression ratio results better than the one of other competing standards such as Jpeg2000 Jpeg LS and PNG Actually the BCIF algo rithm can only handle true color images with a 24 bit color depth 8 bit per primary color it can read or write BMP files but its GUI can integrate with Imagemagick s convert tool to handle also other formats The implementing program has been re leased as open source under the GPL license The website of BCIF containing the results of the benchmarks and last version of the program can be found at www researchandtechnology net bcif The current release of both the BCIF program and of this documentation is a beta version so the program may c
4. has been done by Gabriele Nencini Further details and a contact of the author can be found online at the BCIF website
5. here is a simple workaround convert these images to true color with the above convert command or with any image manipulation program The drawback is that when the image is decompressed the resulting BMP file will still be in true color resulting to be three times bigger than the original BMP The Java implementation The BCIF algorithm has been implemented in Java to allow its cross platform execu tion to realize easily a Graphical User Interface and to allow the possibility to insert BCIF files in a website thanks to an applet that allows client side decompression and visualization The drawback is that the program is much slower and hence may be unsuited for the encoding and decoding of large images Another issue about large images is that unless differently specified the default maximum memory allocated for the program may be insufficient requiring to set a greater maximum memory as explained in the next section The Java distribution comes in two executable JAR files relative to the BCIF viewer and command line utility and to the BCIF gui named bcif jar and bcifGUI jar To launch the BCIF GUI on most systems it is sufficient to click on the JAR file to load the Java virtual machine and execute the file To launch it 1Technical note the only difference between the two jar files is the manifest so anyone of the two can be used in place of the other For example the GUI can be launched from the bcif jar file with the command ja
6. ining the output of the core module of the algorithm The Java viewer and command line utility The BCIF viewer and command line utility recognizes the following syntax java jar bcif jar inputfile options outputfile The inputfile represents the BMP input file to compress of the BCIF file to decompress or view The outputfile is resulting compressed or decompressed file to create if not specified an output filename is chosen by the program by changing the extension of the inputfile to BMP or BCIF depending on the type of output If this file exists then BCIF overwrites it without prompting so use it with care The options can be e v or view Visualizes the input file Default option if the inputfile has exten sion BCIF e c or compress Compress the input file BMP BCIF Default option if the inputfile has extension BMP e d or decompress Decompress the input file BCIF BMP e s or stream Stream output during decompression requires a minimal amount of memory during the process Default option e ns or npstream Do not stream output during decompression requires much more memory but the decoding process may result faster e hc or hashcode Prints an hash code for the image Incompatible with stream and view e h or help Prints help information Sometimes an older JVM may cause Java to ignore the input parameters In this case it will be necessary to update to the newest version Using the
7. ontain some small issues or bugs Feel free to contact the author to signal them an email can be found on the BCIF website Readable formats The BCIF program basically handles true color images in the BMP format The input files to be compressed must be of 8 bits per color 24 bits per pixel be uncom pressed and contain no alpha channel To convert images in this format I suggests the convert free utility from Imagemagick the recommended syntax is example to convert the PNG image lena png to lena bmp convert lena png alpha off type truecolor BMP3 lena bmp This command requires at least imagemagick version 6 3 6 9 previous version do the job without the alpha off option so in this case the user should assure that the input file has no alpha channel otherwise the BCIF program could be un able to read the resulting BMP file The BCIF GUI attempts to call this command automatically if the input file is not in the BMP format Warning when compressing to a BCIF file only the data actually representing the image is stored while other auxiliary information contained in the original file is not saved for example some file formats can contain a transparency channel or metadata about time and place where the picture was taken model of the used camera etc Issue about black and white images since black and white images are represented with 8 bit per pixel bitmaps the BCIF program is actually not able to read them T
8. s and decompress im ages with the BCIF algorithm It is possible to select input and output files with a graphical file chooser and to visualize directly BCIF images If the imagemagick s convert utility is detected i e the convert program can be called in the current working directory then it is used to convert files also from other lossless formats as PNG In this case the original file is converted to a temporary BMP file that is then compressed to a BCIF file The areas of the GUI contain the following components e Input file the input file that must be compressed of decompressed if the convert utility has not been detected it must be a BMP or BCIF file otherwise any format supported by convert is ok The view button visualizes this file Output file the destination of the compression or decompression Action buttons the guess option determines the action to do depending on the input output file extensions Otherwise chose encode to compress images or decode to decompress them e Stream buttons the default option stream decompresses files using a minimal amount of memory and is the recommended option The do not stream option requires a significative amount of memory but in some cases it can be a bit faster e Encode button executes the selected action on the two input and output files e Messages a message about the execution status is displayed in the interface below it there is a text box conta
9. va classpath bcif jar bcif bcifGUI from a command console or to launch the BCIF viewer and command line utility the required syntax is java jar bcifGUI jar java jar bcif jar options The BCIF program requires Java 6 and the source files can be compiled with Java 5 or superior The latest Java release can be obtained on the Java website Encoding and decoding high resolution images memory issues By default the Java Virtual Machine allows a quite limited use of memory Since the actual implementation has yet no memory optimization for encoding and visual ization this could be a problem if attempting to compress large images say greater than 3200x2400 To allow a greater memory use during execution Java can be launched with the Xmxsize flag as in the following examples java Xmx1024M jar bcifGUI jar java Xmx1024M jar bcif jar c large_image bmp large_image bcif The compression procedure requires as a rule of thumb about twice the space required for the uncompressed image plus 7 8 MB for the GUI all this space is not intrinsically necessary for the algorithm and in future versions these limits may be greatly reduced As a quick solution imposing large limits as the 1 GB in the example will solve the problem The decompression process instead as long as the streaming option is specified is almost costless and should not give any problems The Java GUI The Java GUI is a comfortable graphical interface to compres
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