1<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3//EN"> 2<HTML><HEAD> 3 <TITLE>User's Reference - Equalize</TITLE> 4 <META HTTP-EQUIV="keywords" CONTENT="GRAPHICS VISUALIZATION VISUAL PROGRAM DATA 5MINING"> 6 <meta http-equiv="content-type" content="text/html;charset=ISO-8859-1"> 7</HEAD><BODY BGCOLOR="#FFFFFF" link="#00004b" vlink="#4b004b"> 8 <TABLE width=510 border=0 cellpadding=0 cellspacing=0> 9 <TR> 10 <TD><IMG src="../images/spacer.gif" width=80 height=1></TD> 11 <TD><IMG src="../images/spacer.gif" width=49 height=1></TD> 12 <TD><IMG src="../images/spacer.gif" width=24 height=1></TD> 13 <TD><IMG src="../images/spacer.gif" width=100 height=1></TD> 14 <TD><IMG src="../images/spacer.gif" width=3 height=1></TD> 15 <TD><IMG src="../images/spacer.gif" width=127 height=1></TD> 16 <TD><IMG src="../images/spacer.gif" width=6 height=1></TD> 17 <TD><IMG src="../images/spacer.gif" width=50 height=1></TD> 18 <TD><IMG src="../images/spacer.gif" width=71 height=1></TD> 19 </TR> 20 <TR> 21 <TD 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ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Name 56</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Type 57</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">Default 58</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">Description 59</TH></TR><TR> 60<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>data</STRONG></TT> 61</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">scalar field 62</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">none 63</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">data to be equalized 64</TD></TR><TR> 65<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>bins</STRONG></TT> 66</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">integer 67</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">input dependent 68</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">number of equalization bins 69</TD></TR><TR> 70<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>min</STRONG></TT> 71</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">scalar or field 72</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">min of data 73</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">lower bound of equalization 74</TD></TR><TR> 75<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>max</STRONG></TT> 76</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">scalar or field 77</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">max of data 78</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">upper bound of equalization 79</TD></TR><TR> 80<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>ihist</STRONG></TT> 81</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">field 82</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">histogram of data 83</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">input distribution 84</TD></TR><TR> 85<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%"><TT><STRONG>ohist</STRONG></TT> 86</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">field 87</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="20%">uniform distribution 88</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="40%">output distribution 89</TD></TR></TABLE> 90<P><STRONG>Outputs</STRONG> 91<BR> 92<TABLE BORDER> 93<TR> 94<TH ALIGN="LEFT" VALIGN="TOP" WIDTH="25%">Name 95</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="25%">Type 96</TH><TH ALIGN="LEFT" VALIGN="TOP" WIDTH="50%">Description 97</TH></TR><TR> 98<TD ALIGN="LEFT" VALIGN="TOP" WIDTH="25%"><TT><STRONG>equalized</STRONG></TT> 99</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="25%">scalar field 100</TD><TD ALIGN="LEFT" VALIGN="TOP" WIDTH="50%">histogram-equalized data 101</TD></TR></TABLE> 102<P><STRONG>Functional Details</STRONG> 103<P> 104This module equalizes an input data field so that the histogram of the 105output approximates a specified distribution 106(<TT><STRONG>ohist</STRONG></TT>), which by 107default is a uniform distribution. 108<P> 109If <TT><STRONG>data</STRONG></TT> specifies a series, the histogram of the 110entire series is used to construct the probability distribution, 111which is then applied to each field in the series. 112<TABLE CELLPADDING="3"> 113<TR VALIGN="TOP"><TD><P><B><TT><STRONG>data</STRONG></TT> 114</B></TD><TD><P>is the scalar data field to be equalized. 115</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>bins</STRONG></TT> 116</B></TD><TD><P>is the number of bins to be used in creating the equalization 117histogram. 118The default value is 100, unless <TT><STRONG>data</STRONG></TT> consists of 119byte values. 120In that case, the default is: <TT><STRONG>max</STRONG></TT> - 121<TT><STRONG>min</STRONG></TT> + 1 122</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>min</STRONG></TT> 123 and <TT><STRONG>max</STRONG></TT> 124</B></TD><TD><P>specify the range of the data values to be equalized. 125Values outside that range remain unchanged. 126<P><B>Notes: </B><OL> 127<P><LI>If neither parameter is specified, the values used are the minimum 128and maximum of the input field. 129<P><LI>If <TT><STRONG>min</STRONG></TT> is a scalar value, it is the minimum 130value equalized. 131<P><LI>If <TT><STRONG>min</STRONG></TT> is a data field, the minimum data value 132of that field is used. 133<P><LI><TT><STRONG>max</STRONG></TT> is similarly 134interpreted. 135<P><LI>If <TT><STRONG>min</STRONG></TT> is a data field and 136<TT><STRONG>max</STRONG></TT> is unspecified, the 137module uses the minimum and maximum values 138of that field. 139</OL> 140</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>ihist</STRONG></TT> 141</B></TD><TD><P>is the histogram used to determine the equalization function 142required, and by default it is the histogram of 143<TT><STRONG>data</STRONG></TT>. 144If <TT><STRONG>ihist</STRONG></TT> is specified explicitly and the number 145of bins specified does not match the number in the histogram, 146the module resamples the histogram so that it contains the 147specified number. 148</TD></TR><TR VALIGN="TOP"><TD><P><B><TT><STRONG>ohist</STRONG></TT> 149</B></TD><TD><P>is the type of output histogram desired. 150By default, the module equalizes to a uniform distribution. 151You can equalize to some other distribution by specifying an appropriate 152histogram for this parameter. 153</TD></TR></TABLE> 154<P><B>Note: </B>A well-formed histogram (for <TT><STRONG>ihist</STRONG></TT> and 155<TT><STRONG>ohist</STRONG></TT>) consists of a field with a "positions" 156component that defines the bins of the histogram; 157a "connections" component that connects the positions; and a 158"data" component that contains the number of items in 159each bin. 160The data should be connection dependent ("dep" "connections"). 161 162<P><STRONG>Components</STRONG> 163<P> 164Equalize modifies the data component. All other components 165are unmodified. 166<P><STRONG>Example Visual Programs</STRONG> 167<PRE> 168UsingEqualize.net 169</PRE> 170<P><STRONG>See Also</STRONG> 171<P> 172 <A HREF="refgu061.htm#HDRFILTER">Filter</A>, 173 <A HREF="refgu096.htm#HDRMORPH">Morph</A>, 174 <A HREF="refgu071.htm#HDRHISTOGR">Histogram</A> 175 <P> 176 <HR> 177 <DIV align="center"> 178 <P><A href="../allguide.htm"><IMG src="../images/foot-fc.gif" width="94" height="18" border="0" alt="Full Contents"></A> <A href="../qikguide.htm"><IMG src="../images/foot-qs.gif" width="94" height="18" border="0" alt="QuickStart Guide"></A> <A href="../usrguide.htm"><IMG src="../images/foot-ug.gif" width="94" height="18" border="0" alt="User's Guide"></A> <A href="../refguide.htm"><IMG src="../images/foot-ur.gif" width="94" height="18" border="0" alt="User's Reference"></A></P> 179 </DIV> 180 <DIV align="center"> 181 <P><FONT size="-1">[ <A href="http://www.research.ibm.com/dx">OpenDX Home at IBM</A> | <A href="http://www.opendx.org/">OpenDX.org</A> ] </FONT></P> 182 <P></P> 183 </DIV> 184 <P></P> 185 </BODY></HTML> 186
