diff --git a/envi/bil.h b/envi/bil.h
index 344e4b9..ff36234 100644
--- a/envi/bil.h
+++ b/envi/bil.h
@@ -685,6 +685,36 @@ public:
 		return true;
 	}
 
+	//apply mask
+	bool apply_mask(std::string outfile, unsigned char* p){
+
+		std::ofstream target(outfile.c_str(), std::ios::binary);
+
+		unsigned XZ = R[0] * R[2];		//calculate number of a band
+		unsigned L = XZ * sizeof(T);
+
+		T * temp = (T*)malloc(L);
+
+		for (unsigned i = 0; i < R[1]; i++)
+		{
+			getY(temp, i);
+			for ( unsigned j = 0; j < R[2]; j++)
+			{
+				for (unsigned k = 0; k < R[0]; k++)
+				{
+				if(p[i * R[0] + k] == 0)
+					temp[j * R[0] + k] = 0;
+				else
+					continue;
+				}
+			}
+			target.write(reinterpret_cast<const char*>(temp), L);   //write a band data into target file	
+		}
+		target.close();
+		free(temp);
+		return true;
+	}
+
 	//close the file
 	bool close(){
 		file.close();
diff --git a/envi/bip.h b/envi/bip.h
index bd75907..98ec0c2 100644
--- a/envi/bip.h
+++ b/envi/bip.h
@@ -777,6 +777,36 @@ public:
 
 	}
 
+	//apply mask
+	bool apply_mask(std::string outfile, unsigned char* p){
+
+		std::ofstream target(outfile.c_str(), std::ios::binary);
+
+		unsigned ZX = R[2] * R[0];		//calculate number of a band
+		unsigned L = ZX * sizeof(T);
+
+		T * temp = (T*)malloc(L);
+
+		for (unsigned i = 0; i < R[1]; i++)
+		{
+			getY(temp, i);
+			for ( unsigned j = 0; j < R[0]; j++)
+			{
+				for (unsigned k = 0; k < R[2]; k++)
+				{
+				if(p[i * R[0] + k] == 0)
+					temp[j * R[2] + k] = 0;
+				else
+					continue;
+				}
+			}
+			target.write(reinterpret_cast<const char*>(temp), L);   //write a band data into target file	
+		}
+		target.close();
+		free(temp);
+		return true;
+	}
+
 	//close the file
 	bool close(){
 		file.close();
diff --git a/envi/bsq.h b/envi/bsq.h
index 9a97291..a2d06e7 100644
--- a/envi/bsq.h
+++ b/envi/bsq.h
@@ -612,6 +612,37 @@ public:
 		return true;
 
 	}
+
+	//apply mask
+	bool apply_mask(std::string outfile, unsigned char* p){
+
+		std::ofstream target(outfile.c_str(), std::ios::binary);
+
+		unsigned XY = R[0] * R[1];		//calculate number of a band
+		unsigned L = XY * sizeof(T);
+
+		T * temp = (T*)malloc(L);
+
+		for (unsigned i = 0; i < R[2]; i++)
+		{
+			band_index(temp, i);
+			for ( unsigned j = 0; j < XY; j++)
+			{
+				if(p[j] == 0){
+					temp[j] = 0;
+				}
+				else{
+					continue;
+				}
+			}
+			target.write(reinterpret_cast<const char*>(temp), L);   //write a band data into target file	
+		}
+		target.close();
+		free(temp);
+		return true;
+	}
+
+
 	//close the file
 	bool close(){
 		file.close();
diff --git a/envi/envi.h b/envi/envi.h
index 78aeac0..6e9459d 100644
--- a/envi/envi.h
+++ b/envi/envi.h
@@ -302,6 +302,38 @@ public:
 			else
 				std::cout<<"ERROR: unidentified data type"<<std::endl;
 		}
+	}
+
+	//apply mask
+	bool apply_mask(std::string outfile, unsigned char* p)	
+	{
+
+		if(header.interleave == envi_header::BSQ){		//if the infile is bsq file
+			if(header.data_type ==envi_header::float32)
+				return ((bsq<float>*)file)->apply_mask(outfile, p);
+			else if(header.data_type == envi_header::float64)
+				return ((bsq<double>*)file)->apply_mask(outfile, p);
+			else
+				std::cout<<"ERROR: unidentified data type"<<std::endl;
+		}
+
+		else if(header.interleave == envi_header::BIL){		//if the infile is bil file
+			if(header.data_type ==envi_header::float32)
+				return ((bil<float>*)file)->apply_mask(outfile, p);
+			else if(header.data_type == envi_header::float64)
+				return ((bil<double>*)file)->apply_mask(outfile, p);
+			else
+				std::cout<<"ERROR: unidentified data type"<<std::endl;
+		}
+
+		else if(header.interleave == envi_header::BIP){		//if the infile is bip file
+			if(header.data_type ==envi_header::float32)
+				return ((bip<float>*)file)->apply_mask(outfile, p);
+			else if(header.data_type == envi_header::float64)
+				return ((bip<double>*)file)->apply_mask(outfile, p);
+			else
+				std::cout<<"ERROR: unidentified data type"<<std::endl;
+		}
 
 		else{
 			std::cout<<"ERROR: unidentified file type"<<std::endl;
--
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