diff --git a/LibCmo/CK2/CKBitmapData.cpp b/LibCmo/CK2/CKBitmapData.cpp
index cfdc777..bef65f9 100644
--- a/LibCmo/CK2/CKBitmapData.cpp
+++ b/LibCmo/CK2/CKBitmapData.cpp
@@ -1,6 +1,7 @@
 #include "CKBitmapData.hpp"
 #include "CKContext.hpp"
 #include "CKStateChunk.hpp"
+#include "CKFile.hpp"
 #include "DataHandlers/CKBitmapHandler.hpp"
 #include "MgrImpls/CKPathManager.hpp"
 #include <memory>
@@ -123,7 +124,7 @@ namespace LibCmo::CK2 {
 		return false;
 	}
 
-	void CKBitmapData::WriteSpecificFormatBitmap(CKStateChunk* chk, const VxMath::VxImageDescEx* slot) {
+	void CKBitmapData::WriteSpecificFormatBitmap(CKStateChunk* chk, const VxMath::VxImageDescEx* slot, const CKBitmapProperties* savefmt) {
 
 	}
 
@@ -250,7 +251,98 @@ namespace LibCmo::CK2 {
 	}
 
 	bool CKBitmapData::DumpToChunk(CKStateChunk* chunk, CKFileVisitor* file, const CKBitmapDataWriteIdentifiers& identifiers) {
-		return false;
+		// resolve save fmt and save opt
+		CK_TEXTURE_SAVEOPTIONS saveopt = GetSaveOptions();
+		if (saveopt == CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_USEGLOBAL) {
+			saveopt = m_Context->GetGlobalImagesSaveOptions();
+		}
+		CKBitmapProperties savefmt(GetSaveFormat());
+		if (GetSaveOptions() == CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_USEGLOBAL) {
+			savefmt = m_Context->GetGlobalImagesSaveFormat();
+		}
+
+		// filter external / original files
+		// the slot can not fulfill extrnal saving requirement will be written in raw data
+		CKDWORD slotcount = GetSlotCount();
+		XContainer::XBitArray validExternalSavingSlot;
+		if (saveopt == CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_EXTERNAL) {
+			for (CKDWORD i = 0; i < slotcount; ++i) {
+				if (GetSlotFileName(i) == nullptr) {
+					saveopt = CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_RAWDATA;
+				} else {
+					XContainer::NSXBitArray::Set(validExternalSavingSlot, i);
+				}
+			}
+		}
+		if (saveopt == CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_INCLUDEORIGINALFILE) {
+			for (CKDWORD i = 0; i < slotcount; ++i) {
+				if (file->AddSavedFile(GetSlotFileName(i))) {
+					XContainer::NSXBitArray::Set(validExternalSavingSlot, i);
+				} else {
+					saveopt = CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_RAWDATA;
+				}
+			}
+		}
+
+		// save data
+		if (saveopt == CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_RAWDATA) {
+			// save as raw data
+			chunk->WriteIdentifier(identifiers.m_RawData);
+			chunk->WriteStruct(slotcount);
+
+			VxMath::VxImageDescEx invalidDesc;
+			for (CKDWORD i = 0; i < slotcount; ++i) {
+				if (XContainer::NSXBitArray::IsSet(validExternalSavingSlot, i)) {
+					// if this slot can save as external, pass a invalid desc to writer
+					WriteRawBitmap(chunk, &invalidDesc);
+				} else {
+					// otherwise, pass the real slot data
+					WriteRawBitmap(chunk, GetImageDesc(i));
+				}
+			}
+
+		}
+		if (saveopt == CK_TEXTURE_SAVEOPTIONS::CKTEXTURE_IMAGEFORMAT) {
+			// save as special format
+			chunk->WriteIdentifier(identifiers.m_SpecificFormat);
+			chunk->WriteStruct(slotcount);
+
+			// prepare height, width, bpp data
+			CKDWORD height = 0, width = 0, bpp = 32;
+			for (CKDWORD i = 0; i < slotcount; ++i) {
+				VxMath::VxImageDescEx* desc = GetImageDesc(i);
+				if (desc->IsValid()) {
+					height = desc->GetHeight();
+					width = desc->GetWidth();
+					break;
+				}
+			}
+			// write it
+			chunk->WriteStruct(width);
+			chunk->WriteStruct(height);
+			chunk->WriteStruct(bpp);
+
+			// write slot one by one
+			for (CKDWORD i = 0; i < slotcount; ++i) {
+				WriteSpecificFormatBitmap(chunk, GetImageDesc(i), &savefmt);
+			}
+
+		}
+
+		// write filename
+		{
+			chunk->WriteIdentifier(identifiers.m_FileNames);
+			chunk->WriteStruct(slotcount);
+
+			XContainer::XString filename;
+			for (CKDWORD i = 0; i < slotcount; ++i) {
+				XContainer::NSXString::FromCKSTRING(filename, GetSlotFileName(i));
+				m_Context->GetPathManager()->GetFileName(filename);
+				chunk->WriteString(filename);
+			}
+		}
+
+		return true;
 	}
 
 #pragma endregion
@@ -361,7 +453,9 @@ namespace LibCmo::CK2 {
 
 	CKSTRING CKBitmapData::GetSlotFileName(CKDWORD slot) const {
 		if (slot >= m_Slots.size()) return nullptr;
-		return m_Slots[slot].m_FileName.c_str();
+		// return nullptr if no corresponding filename
+		if (m_Slots[slot].m_FileName.empty()) return nullptr;
+		else return m_Slots[slot].m_FileName.c_str();
 	}
 
 #pragma endregion
diff --git a/LibCmo/CK2/CKBitmapData.hpp b/LibCmo/CK2/CKBitmapData.hpp
index 938bdc2..830f5e6 100644
--- a/LibCmo/CK2/CKBitmapData.hpp
+++ b/LibCmo/CK2/CKBitmapData.hpp
@@ -43,7 +43,7 @@ namespace LibCmo::CK2 {
 		static bool ReadSpecificFormatBitmap(CKStateChunk* chk, VxMath::VxImageDescEx* slot);
 		static bool ReadRawBitmap(CKStateChunk* chk, VxMath::VxImageDescEx* slot);
 		static bool ReadOldRawBitmap(CKStateChunk* chk, VxMath::VxImageDescEx* slot);
-		static void WriteSpecificFormatBitmap(CKStateChunk* chk, const VxMath::VxImageDescEx* slot);
+		static void WriteSpecificFormatBitmap(CKStateChunk* chk, const VxMath::VxImageDescEx* slot, const CKBitmapProperties* savefmt);
 		static void WriteRawBitmap(CKStateChunk* chk, const VxMath::VxImageDescEx* slot);
 
 		bool ReadFromChunk(CKStateChunk* chunk, CKFileVisitor* file, const CKBitmapDataReadIdentifiers& identifiers);
diff --git a/LibCmo/CK2/CKDefines.hpp b/LibCmo/CK2/CKDefines.hpp
index 5892e45..84eb589 100644
--- a/LibCmo/CK2/CKDefines.hpp
+++ b/LibCmo/CK2/CKDefines.hpp
@@ -110,6 +110,10 @@ namespace LibCmo::CK2 {
 			return m_Data;
 		}
 
+		CKDWORD GetSize() const {
+			return c_DataLen;
+		}
+
 		bool operator==(const CKFileExtension& rhs) const {
 			return CKStrEqualI(m_Data, rhs.m_Data);
 		}
diff --git a/LibCmo/CK2/CKFile.hpp b/LibCmo/CK2/CKFile.hpp
index ddf10a2..29a2a90 100644
--- a/LibCmo/CK2/CKFile.hpp
+++ b/LibCmo/CK2/CKFile.hpp
@@ -174,6 +174,8 @@ namespace LibCmo::CK2 {
 
 		const CKFileObject* GetFileObjectByIndex(CKDWORD index);
 		CKDWORD GetIndexByObjectID(CK_ID objid);
+		bool AddSavedFile(CKSTRING u8FileName);
+
 	protected:
 		bool m_IsReader;
 		CKFileReader* m_Reader;
diff --git a/LibCmo/CK2/CKFileOthers.cpp b/LibCmo/CK2/CKFileOthers.cpp
index 18a03cc..e1e9b6f 100644
--- a/LibCmo/CK2/CKFileOthers.cpp
+++ b/LibCmo/CK2/CKFileOthers.cpp
@@ -334,6 +334,14 @@ namespace LibCmo::CK2 {
 		return finder->second;
 	}
 
+	bool CKFileVisitor::AddSavedFile(CKSTRING u8FileName) {
+		if (m_IsReader) {
+			return false;
+		} else {
+			return m_Writer->AddSavedFile(u8FileName);
+		}
+	}
+
 #pragma endregion
 
 }
diff --git a/LibCmo/CK2/DataHandlers/CKBitmapHandler.cpp b/LibCmo/CK2/DataHandlers/CKBitmapHandler.cpp
index ca8f222..1ae8be0 100644
--- a/LibCmo/CK2/DataHandlers/CKBitmapHandler.cpp
+++ b/LibCmo/CK2/DataHandlers/CKBitmapHandler.cpp
@@ -323,8 +323,8 @@ namespace LibCmo::CK2::DataHandlers {
 		return nullptr;
 	}
 
-	std::unique_ptr<CKBitmapHandler, CKBitmapHandlerDeleter> CKBitmapHandler::GetBitmapHandlerWrapper(const CKFileExtension& ext, const CKGUID& guid) {
-		return std::unique_ptr<CKBitmapHandler, CKBitmapHandlerDeleter>(GetBitmapHandler(ext, guid));
+	CKBitmapHandlerWrapper_t CKBitmapHandler::GetBitmapHandlerWrapper(const CKFileExtension& ext, const CKGUID& guid) {
+		return CKBitmapHandlerWrapper_t(GetBitmapHandler(ext, guid));
 	}
 
 	void CKBitmapHandlerDeleter::operator()(CKBitmapHandler* handler) {
diff --git a/LibCmo/CK2/DataHandlers/CKBitmapHandler.hpp b/LibCmo/CK2/DataHandlers/CKBitmapHandler.hpp
index bdeed1f..38f5dbd 100644
--- a/LibCmo/CK2/DataHandlers/CKBitmapHandler.hpp
+++ b/LibCmo/CK2/DataHandlers/CKBitmapHandler.hpp
@@ -16,6 +16,10 @@ namespace LibCmo::CK2::DataHandlers {
 		CKBitmapHandlerDeleter(const CKBitmapHandlerDeleter&) noexcept {}
 		void operator()(CKBitmapHandler* handler);
 	};
+	/**
+	 * @brief The type of Auto-free wrapper of CKBitmapHandler.
+	*/
+	using CKBitmapHandlerWrapper_t = std::unique_ptr<CKBitmapHandler, CKBitmapHandlerDeleter>;
 
 	/**
 	 * The interface about processing bitmap data between raw data and specific data.
@@ -41,7 +45,7 @@ namespace LibCmo::CK2::DataHandlers {
 		/**
 		 * @brief A auto free wrapper for GetBitmapHandler
 		*/
-		static std::unique_ptr<CKBitmapHandler, CKBitmapHandlerDeleter> GetBitmapHandlerWrapper(const CKFileExtension& ext, const CKGUID& guid);
+		static CKBitmapHandlerWrapper_t GetBitmapHandlerWrapper(const CKFileExtension& ext, const CKGUID& guid);
 		/**
 		 * @brief General CKBitmapHandler disposer
 		 * @param handler[in] The handler need to be free.