This routine has been replaced with the METADATA property to ENVIRaster.

Use this procedure to retrieve user-defined header values using the argument User_Keyword. All standard header information is available by using the procedure ENVI_FILE_QUERY. However, to access user-defined header values, you must use ENVI_GET_HEADER_VALUE. Optional keywords allow you to set the returned data type.

Syntax

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Result = ENVI_GET_HEADER_VALUE(FID, User_Keyword [, /BYTE] [, /DOUBLE] [, DT={1 | 2 | 3 | 4 | 5 | 6 | 9 | 12 | 13 | 14 | 15}] [, /FIX] [, /FLOAT] [, /L64] [, /LONG] [, /UL64] [, /ULONG] [, UNDEFINED=variable])

Arguments

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FID

This is the file ID of the open file. This value is returned from the keyword R_FID in the ENVI_OPEN_FILE procedure. FID is a long integer with a value greater than 0. An invalid file ID has a value of -1.

User_Keyword

This is a case-insensitive string that must exactly match the string you specified in the KEYWORD keyword to ENVI_ASSIGN_HEADER_VALUE.

Keywords

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BYTE (optional)

Set this keyword to return the User_Keyword values as byte numbers. You should not set this keyword if you use the keywords DOUBLE, DT, FIX, FLOAT, L64, LONG, UL64, or ULONG. The default is to return the values as a string.

DOUBLE (optional)

Set this keyword to return the User_Keyword values as double-precision numbers. You should not set this keyword if you use the keywords BYTE, DT, FIX, FLOAT, L64, LONG, UL64, or ULONG. The default is to return the values as a string.

DT (optional)

This keyword indicates the IDL data type of the output data. Set the keyword to one of the following integer values:

• 1: Byte (8 bits)
• 2: Integer (16 bits)
• 3: Long integer (32 bits)
• 4: Floating-point (32 bits)
• 5: Double-precision floating-point (64 bits)
• 6: Complex (2x32 bits)
• 9: Double-precision complex (2x64 bits)
• 12: Unsigned integer (16 bits)
• 13: Unsigned long integer (32 bits)
• 14: Long 64-bit integer
• 15: Unsigned long 64-bit integer

FIX (optional)

Set this keyword to return the User_Keyword values as integer numbers. You should not set this keyword if you use the keywords BYTE, DOUBLE, DT, FLOAT, L64, LONG, UL64, or ULONG. The default is to return the values as a string.

FLOAT (optional)

Set this keyword to return the User_Keyword values as floating-point numbers. You should not set this keyword if you use the keywords BYTE, DOUBLE, DT, FIX, L64, LONG, UL64, or ULONG. The default is to return the values as a string.

L64 (optional)

Set this keyword to return the User_Keyword values as 64-bit integers. You should not set this keyword if you use the keywords BYTE, DOUBLE, DT, FIX, FLOAT, LONG, UL64, or ULONG. The default is to return the values as a string.

LONG (optional)

Set this keyword to return the User_Keyword values as long numbers. You should not set this keyword if you use the keywords BYTE, DOUBLE, DT, FIX, FLOAT, L64, UL64, or ULONG. The default is to return the values as a string.

UL64 (optional)

Set this keyword to return the User_Keyword values as unsigned 64-bit integers. You should not set this keyword if you use the keywords BYTE, DOUBLE, DT, FIX, FLOAT, L64, LONG, or ULONG. The default is to return the values as a string.

ULONG (optional)

Set this keyword to return the User_Keyword values as unsigned long numbers. You should not set this keyword if you use the keywords BYTE, DOUBLE, DT, FIX, FLOAT, LONG, L64, or UL64. The default is to return the values as a string.

UNDEFINED (optional)

Use this keyword to specify a named variable that is set to 1 if User_Keyword is not present, or 0 if this argument is present.