MFC课设时做了一个bmp格式转jpg格式出错，求大神解答

BmpVsJpgDlg.obj : error LNK2001: unresolved external symbol "public: int thiscall CDib::Write(class CFile *)" (?Write@CDib@@QAEHPAVCFile@@@Z)
BmpVsJpgDlg.obj : error LNK2001: unresolved external symbol "public: int __thiscall CDib::ConvertFormat(unsigned short)" (?ConvertFormat@CDib@@QAEHG@Z)
BmpVsJpgDlg.obj : error LNK2001: unresolved external symbol "public: int __thiscall CDib::Attach(void *)" (?Attach@CDib@@QAEHPAX@Z)
BmpVsJpgDlg.obj : error LNK2001: unresolved external symbol "public: void * __thiscall CDib::GetHandle(void)" (?GetHandle@CDib@@QAEPAXXZ)
BmpVsJpgDlg.obj : error LNK2001: unresolved external symbol "public: int __thiscall CJpeg::Load(char const *)" (?Load@CJpeg@@QAEHPBD@Z)
BmpVsJpgDlg.obj : error LNK2001: unresolved external symbol "public: int __thiscall CJpeg::Save(char const *,class CDib *,int,int)" (?Save@CJpeg@@QAEHPBDPAVCDib@@HH@Z)
BmpVsJpgDlg.obj : error LNK2001: unresolved external symbol "public: int __thiscall CDib::Read(class CFile *)" (?Read@CDib@@QAEHPAVCFile@@@Z)
Dib.obj : error LNK2001: unresolved external symbol "public: virtual void __thiscall CDib::Serialize(class CArchive &)" (?Serialize@CDib@@UAEXAAVCArchive@@@Z)
Dib.obj : error LNK2001: unresolved external symbol "public: virtual struct CRuntimeClass * __thiscall CDib::GetRuntimeClass(void)const " (?GetRuntimeClass@CDib@@UBEPAUCRuntimeClass@@XZ)
dibapi.obj : error LNK2001: unresolved external symbol __imptimeGetTime@0

直接用CImage类，保存的时候改下后缀就行了