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width="95%" border="0" cellpadding="0"> <tr> <td width="2%" height="19"> </td> <td width="98%"><span class="smallblacktxt"><a href="../../Default.htm">Home</a> > <a href="../../Home2/vertmkts/LTProdOvrvw.htm">Products</a> > <a href="../../Home2/vertmkts/LTProdOvrvw.htm">Toolkits</a> > <a href="../Raster/Raster-Products-n.htm">Raster</a> > <a href="default.htm">LEADTOOLS for Pocket PC </a> > CCITT G3/G4 Compression </span></td> </tr> </table></TD> <TD> </TD> </TR> <TR> <TD valign="top"> <TABLE width="590" height="389" border="0" cellpadding="0" cellspacing="0" bgcolor="#FFFFFF"> <TR> <TD valign="top"><TABLE width="100%" border="0" cellpadding="12" cellspacing="0"> <TR> <TD><table width="25%" border="0" align="right" cellpadding="2" cellspacing="0" class="PaddedTable"> <tr> <td><div align="right"><a href="/Survey/WebEvalSurvey.asp?category=PocketPC" onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('try','','../../images/05tryON-productpages.gif',1)"><img src="../../images/05try-productpages.gif" name="try" width="61" height="55" border="0"></a></div></td> <td><a href="http://shop.leadtools.com/shopdisplayproducts.asp?catalogID=19&cat= " onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('buy','','../../images/05buyON-productpages.gif',1)"><img src="../../images/05buy-productpages.gif" name="buy" width="61" height="55" border="0"></a></td> </tr> </table> <h1 class="grayheading">CCITT G3/G4 Compression - Pocket PC 2002 SDK </h1> <p class="text"><span class="normal">LEADTOOLS offers more compression options than any other Pocket PC 2002 toolkit on the market. LEADTOOLS supports industry standard and proprietary alternative compression algorithms including:</span></p> <table border="0" cellpadding="5" width="90%" align="center"> <tr> <td align="left" width="49%" class="text"><b><a href="Raster-Compression-JPEG2000.htm"> JPEG2000</a></b></td> <td align="left" width="51%" class="text"><b><a href="Raster-Compression-JPEG.htm">JPEG</a></b></td> </tr> <tr> <td align="left" width="49%" class="text"><b><a href="Raster-Compression-CMP.htm">LEAD CMP</a></b></td> <td align="left" width="51%" class="text"><b><a href="Raster-Compression-LZW.htm">LZW</a></b></td> </tr> <tr> <td align="left" width="49%" class="text"><b><a href="Raster-Compression-RLE.htm">RLE / PackBits</a></b></td> <td align="left" width="51%" class="text"><b><a href="Raster-Compression-ZIPLIB.htm">ZIPLIB</a></b></td> </tr> <tr> <td align="left" width="49%" class="text"><b><a href="Raster-Compression-CCITT.htm">CCITT G3/G4</a></b></td> <td align="left" width="51%" class="text"><b><a href="Raster-Compression-Huffman.htm">Huffman</a></b></td> </tr> <tr> <td align="left" width="49%" class="text"><b><a href="Raster-Compression-Arithmetic.htm">Arithmetic</a></b></td> <td align="left" width="51%" class="text"><b><a href="Raster-Compression-CMW.htm">LEAD CMW</a></b></td> </tr> </table> <h2 class="SubHeading"> </h2> <h2 class="SubHeading"><b>CCITT G3/G4</b> Compression</h2> <p class="text">Both Group 3 and Group 4 encode the source image line by line. The difference between the two schemes is in the way the two standards handle successive scanlines. In Group 3 1-D, each scanline is encoded independently, whereas in Group 4, scanlines are encoded with reference to the previous one, resulting in improved compression ratios. <p class="text">In Group 3 1-D, a scanline is encoded as a set of runs, each representing a number of white or black pixels, with white runs alternating with black runs. Every run is encoded using a variable number of bits, which can be uniquely identified upon decoding. This means that frequently occurring lengths of run may be encoded very efficiently, while infrequent ones cause the data to grow. For example, a white run of 2 or 3 pixels can be encoded using just 2 bits, while a run of 1000 pixels can be encoded in 25.</p> <p class="text">Group 4 encoding is more complex as compared to Group 3 encoding. Each scanline is compared with the previous one. Because of this, vertical features in the source image are used to achieve high compression ratios. </p> <p class="text">There is also a G3 2-D. G3 2-D is a combination of G3 1-D and G4 compression schemes</p> <h1> </h1> <P class="SubHeading"><a href="default.htm">Back to the Pocket PC 2002 Main Page</a></P> <P class="smallgraytxt-nonjust"> </P> <P class="text"> <script language="JavaScript" type="text/JavaScript">  </script> <body> <P align="center"><span class="smallgraytxt-nonjust"><strong>LEADTOOLS Sales:</strong> 704-332-5532 | </span><a href="mailto:sales@leadtools.com" class="smallgraytext-nounder">sales@leadtools.com</a><span class="smallgraytxt-nonjust"><br> <strong>LEADTOOLS Support:</strong> 704-372-9681 |</span> <a href="mailto:support@leadtools.com" class="smallgraytext-nounder">support@leadtools.com </a></P> <P align="center"><a href="/Home2/vertmkts/LTProdOvrvw.htm" class="smallgraytext-nounder">Products</a> <span class="smallgraytxt-nonjust">| </span><a href="/Survey/WebEvalSurvey.asp" class="smallgraytext-nounder">Downloads</a><span class="smallgraytxt-nonjust"> | </span><a href="/Home2/general/ordermain.htm" class="smallgraytext-nounder">Order</a><span class="smallgraytxt-nonjust"> | </span><a href="/support/default.htm" class="smallgraytext-nounder">Support</a><span class="smallgraytxt-nonjust"> | </span><a href="/Home2/general/corporate.htm" class="smallgraytext-nounder">Corporate</a><span class="smallgraytxt-nonjust"> | </span><a href="/Home2/press/press.htm" class="smallgraytext-nounder">News</a></P> <map name="MapHeader"> <area shape="rect" coords="3,2,199,42" href="/Default.htm"> </map> </P> </TD> </TR> </TABLE></TD> </TR> </TABLE></TD> <TD class="whitetext"> <IMG src="../../images/04New-web-design_07.gif" width=5 height=389 alt=""></TD> </TR> <TR> <TD colspan="5" valign="top"> <DIV align="right"> <script src="http://www.google-analytics.com/urchin.js" type="text/javascript"> </script> <script type="text/javascript"> _uacct = "UA-378747-1"; urchinTracker(); </script> <style type="text/css">  </style> <table width="756" border="0" align="center" cellpadding="3" cellspacing="2"> <tr> <td><div align="center" class="copyright"> <p align="right" class="copyright">Copyright © 2008 All Rights Reserved. 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