Release 9.2
Part No. A96121-01
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| Oracle® interMedia Java Classes User's Guide and Reference Release 9.2 Part No. A96121-01 |
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The OrdImageSignature class is used to represent an instance of the ORDSYS.ORDImageSignature database type in a Java application. The OrdImageSignature class includes a method to generate an image signature, as well as static methods to compare two image signatures.
If your application modifies the OrdImageSignature object, you must perform a SQL update operation to make those changes permanent.
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Note : To take advantage of the increased performance that is possible using image matching with image signature indexes on the underlying tables, use the IMGSimilar and IMGScore SQL operators.See Oracle interMedia User's Guide and Reference for more information about image signature indexes. |
You will need to include the following import statements in your Java file to run interMedia methods:
import java.sql.*; import java.io.*; import oracle.jdbc.driver.*; import oracle.sql.*; import oracle.ord.im.*;
The examples in this reference chapter are based on the assumption that the following operations have already been performed:
A connection has been made to a table that contains a column of type OrdImageSignature.
A local OrdImageSignature object named matchObj has been created and populated with data.
This section presents reference information on the methods that operate on OrdImageSignature objects.
Format
public static float evaluateScore(OrdImageSignature signature1, OrdImageSignature signature2,
String attrWeights)
Description
Compares two image signatures, returning a score that indicates the degree of difference between the image signatures. This method compares the image signatures in signature1 and signature2 using weights specified for one or more visual attributes. Returns a score between 0.0 and 100.0, where a lower value indicates a closer match.
Specify a weight in the range 0.0 to 1.0 for one or more of the following visual attributes: color, shape, texture, location.
You must specify a value greater than 0.0 for at least one of the following attributes: color, shape, or texture. The location attribute indicates the importance of the distribution of the color, shape, or texture features in the images. During processing, the values are normalized such that they total 1.0. For example:
color=0.7,shape-0.3
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Note : The ORDImageSignature evaluateScore( ) method operates on two image signatures, not on indexes on database tables. Therefore, this method cannot take advantage of the increased performance that is possible using image matching with image signature indexes on the underlying tables. To use image signature indexes, use the IMGSimilar and IMGScore SQL operators.See Oracle interMedia User's Guide and Reference for more information about image signature indexes. |
Parameters
The first OrdImageSignature.
An OrdImageSignature to be compared to signature1.
A String that specifies a list of one or more visual attributes and the weight to be applied to each attribute.
Return Value
This method returns the score, as a floating-point value.
Exceptions
java.sql.SQLException
This exception is thrown if an error occurs calling the evaluateScore( ) method in the database.
Examples
float score = matchObj.evaluateScore(signature1, signature2, "color=1.0");
where:
signature1: is the first signature.
signature2: is the second signature, which will be compared to signature1.
color=1.0: is the weight to apply to the color visual attribute.
Format
public void generateSignature(OrdImage img)
Description
Generates an image signature for the specified image.
Parameters
An OrdImage object from which to generate the signature.
Return Value
None.
Exceptions
SQLException
This exception is thrown if an error occurs calling the generateSignature( ) method in the database.
Examples
matchObj.generateSignature(imgObj);
where:
imgObj: is the image object whose signature is to be generated.
Format
public static oracle.sql.CustomDatumFactory getFactory( )
Description
Returns the OrdImageSignature CustomDatumFactory interface for use by the getCustomDatum( ) method. Specify the getFactory( ) method as the factory parameter of the getCustomDatum( ) method when retrieving an OrdImageSignature object from an OracleResultSet or OracleCallableStatement object.
Parameters
None.
Return Value
This method returns the OrdImageSignature implementation of the CustomDatumFactory interface.
Exceptions
None.
Examples
OrdImageSignature sig = (OrdImageSignature)rset.getCustomDatum( 1, OrdImageSignature.getFactory() );
Format
public static int isSimilar(OrdImageSignature signature1, OrdImageSignature signature2,
String attrWeights, float threshold)
Description
Compares two image signatures, returning a status that indicates if the degree of difference between the image signatures is within a specified threshold. This method compares the image signatures in signature1 and signature2 using weights specified for one or more visual attributes. The result of the comparison is a score between 0.0 and 100.0, where a lower value indicates a closer match. If the score is less than or equal to the specified threshold, the images are considered a match and the method returns 1; otherwise, the method returns 0.
Specify a weight in the range 0.0 to 1.0 for one or more of the following visual attributes: color, shape, texture, location.
You must specify a value greater than 0.0 for at least one of the following attributes: color, shape, or texture. The location attribute indicates the importance of the distribution of the color, shape, or texture features in the images. During processing, the values are normalized such that they total 1.0. For example:
color=0.7,shape-0.3
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Note : The ORDImageSignature isSimilar( ) method operates on two image signatures, not on indexes on database tables. Therefore, this method cannot take advantage of the increased performance that is possible using image matching with image signature indexes on the underlying tables. To use image signature indexes, use the IMGSimilar and IMGScore SQL operators.See Oracle interMedia User's Guide and Reference for more information about image signature indexes. |
Parameters
The first OrdImageSignature.
An OrdImageSignature to be compared to signature1.
A String that specifies a list of one or more visual attributes and the weight to be applied to each attribute.
A floating-point value that specifies the degree of similarity required for the two images to be considered a match.
Return Value
This method returns an integer value of 1 if the images match; otherwise, it returns 0.
Exceptions
java.sql.SQLException
This exception is thrown if an error occurs calling the isSimilar( ) method in the database.
Examples
int i = matchObj.isSimilar(signature1, signature2, "color=0.5,shape=0.5", 10);
where:
signature1: is the first signature.
signature2: is the second signature, which will be compared to signature1.
color=0.5,shape=0.5: is the weight to apply to these visual attributes.
10: is the value that the score must be less than or equal to in order to be considered a match.
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