<?xml version="1.0" encoding="utf-8"?>
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  <import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
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  <import namespace="http://fasb.org/us-gaap/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd"/>
  <import namespace="http://xbrl.sec.gov/cef/2024" schemaLocation="https://xbrl.sec.gov/cef/2024/cef-2024.xsd"/>
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        <link:definition>0000 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calamos.com/role/FinancialHighlights" id="FinancialHighlights">
        <link:definition>0000 - Disclosure - Senior Securities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.calamos.com/role/FeeTable" id="FeeTable">
        <link:definition>0000 - Disclosure - Summary of Fees &amp; Expenses And Example Table</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
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      <link:roleType roleURI="http://www.calamos.com/role/GeneralDescriptionOfRegistrant" id="GeneralDescriptionOfRegistrant">
        <link:definition>0000 - Disclosure - General Description of Registrant</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
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      <link:roleType roleURI="http://www.calamos.com/role/CapitalStockLongTermDebtAndOtherSecurities" id="CapitalStockLongTermDebtAndOtherSecurities">
        <link:definition>0000 - Disclosure - Capital Stock Long Term Debt And Other Securities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
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  <element name="BenchmarkRateRiskAndLiborCessationMember" id="chi_BenchmarkRateRiskAndLiborCessationMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="CashHoldingsRiskMember" id="chi_CashHoldingsRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="CommonSharesMember" id="chi_CommonSharesMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="DeclineInNetAssetValueRiskMember" id="chi_DeclineInNetAssetValueRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="DerivativesRiskMember" id="chi_DerivativesRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="DiminishedVotingPowerAndExcessCashRiskMember" id="chi_DiminishedVotingPowerAndExcessCashRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="EmergingMarketsRiskMember" id="chi_EmergingMarketsRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="EquitySecuritiesRiskMember" id="chi_EquitySecuritiesRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="FacilityMember" id="chi_FacilityMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="ForwardCurrencyExchangeContractsRiskMember" id="chi_ForwardCurrencyExchangeContractsRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="GeneralDerivativeRiskMember" id="chi_GeneralDerivativeRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="GeographicConcentrationRisksMember" id="chi_GeographicConcentrationRisksMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="GeographicFocusRiskMember" id="chi_GeographicFocusRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="HighYieldSecuritiesRiskMember" id="chi_HighYieldSecuritiesRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="InflationRiskMember" id="chi_InflationRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="InterestRateRisksMember" id="chi_InterestRateRisksMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="InterestRateTransactionsRiskMember" id="chi_InterestRateTransactionsRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="InvestingInRealEstateInvestmentTrustsRiskReitMember" id="chi_InvestingInRealEstateInvestmentTrustsRiskReitMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="LeverageRiskForAllFundsExceptCpzMember" id="chi_LeverageRiskForAllFundsExceptCpzMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="LeverageRiskMember" id="chi_LeverageRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="LoanMember" id="chi_LoanMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
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  <element name="VolatilityRiskMember" id="chi_VolatilityRiskMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
</schema>
