item
Handle to the item which represents the item having the property. You can retrieve this parameter by either calling the GetRootItem method to get the device's root item itself or by enumerating the child items of the device through a call to EnumChildItems method.
propertyIdName
This string should contain the equivalent property Id string for the WIA property ID. Use the GetPropertyIdString method to get this string for the property ID.
If you passed null for this parameter, then the WIA toolkit will use the property ID passed through the third parameter,
propertyId
The property ID for the value being sought. For a list of available property IDs, see WiaPropertyId.
This parameter is required only if the second parameter, propertyIdName, is null; otherwise, you can pass 0 for this parameter.
value
The GUID value to set.
Call this function to set the Guid value for any WiaVariableTypes.Clsid property such as WiaPropertyId.ItemFormat
For more information, refer to Managing WIA Sources.
Refer to WiaSession.GetPropertyGuid