diff --git a/stim/envi/bil.h b/stim/envi/bil.h
index d9874a8..6c3189b 100644
--- a/stim/envi/bil.h
+++ b/stim/envi/bil.h
@@ -818,7 +818,7 @@ public:
 
 	/// @param outfile is the name of the masked output file
 	/// @param p is a pointer to memory of size X * Y, where p(i) = 0 for pixels that will be set to zero.
-	bool apply_mask(std::string outfile, unsigned char* p){
+	bool apply_mask(std::string outfile, unsigned char* p, bool PROGRESS = false){
 
 		std::ofstream target(outfile.c_str(), std::ios::binary);
 
@@ -842,6 +842,7 @@ public:
 				}
 			}
 			target.write(reinterpret_cast<const char*>(temp), L);   //write a band data into target file	
+			if(PROGRESS) progress = (double)(i+1) / (double)Y() * 100;
 		}
 		target.close();
 		free(temp);
diff --git a/stim/envi/bip.h b/stim/envi/bip.h
index 9807229..2b7b1f9 100644
--- a/stim/envi/bip.h
+++ b/stim/envi/bip.h
@@ -745,7 +745,7 @@ public:
 
 	/// @param outfile is the name of the masked output file
 	/// @param p is a pointer to memory of size X * Y, where p(i) = 0 for pixels that will be set to zero.
-	bool apply_mask(std::string outfile, unsigned char* p){
+	bool apply_mask(std::string outfile, unsigned char* p, bool PROGRESS = false){
 
 		std::ofstream target(outfile.c_str(), std::ios::binary);
 
@@ -768,6 +768,7 @@ public:
 				}
 			}
 			target.write(reinterpret_cast<const char*>(temp), L);   //write the edited band data into target file
+			if(PROGRESS) progress = (double)(i+1) / (double)Y() * 100;
 		}
 		target.close();						//close the target file
 		free(temp);							//free allocated memory
diff --git a/stim/envi/bsq.h b/stim/envi/bsq.h
index b7f4e45..c969536 100644
--- a/stim/envi/bsq.h
+++ b/stim/envi/bsq.h
@@ -734,7 +734,7 @@ public:
 
 	/// @param outfile is the name of the masked output file
 	/// @param p is a pointer to memory of size X * Y, where p(i) = 0 for pixels that will be set to zero.
-	bool apply_mask(std::string outfile, unsigned char* p){
+	bool apply_mask(std::string outfile, unsigned char* p, bool PROGRESS = false){
 
 		std::ofstream target(outfile.c_str(), std::ios::binary);
 
@@ -756,6 +756,7 @@ public:
 				}
 			}
 			target.write(reinterpret_cast<const char*>(temp), L);   //write the XY slice at that band to disk
+			if(PROGRESS) progress = (double)(i + 1) / (double)Z() * 100;
 		}
 		target.close();
 		free(temp);
diff --git a/stim/envi/envi.h b/stim/envi/envi.h
index 6d949e1..99bd357 100644
--- a/stim/envi/envi.h
+++ b/stim/envi/envi.h
@@ -541,32 +541,31 @@ public:
 
 	/// @param outfile is the name of the resulting masked output file
 	/// @param p is memory of size X*Y containing the mask (0 = false, all other values are true)
-	bool apply_mask(std::string outfile, unsigned char* p)
+	void apply_mask(std::string outfile, unsigned char* p, bool PROGRESS = false)
 	{
-		header.save(outfile + ".hdr");
 		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);
+				((bsq<float>*)file)->apply_mask(outfile, p, PROGRESS);
 			else if (header.data_type == envi_header::float64)
-				return ((bsq<double>*)file)->apply_mask(outfile, p);
+				((bsq<double>*)file)->apply_mask(outfile, p, PROGRESS);
 			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);
+				((bil<float>*)file)->apply_mask(outfile, p, PROGRESS);
 			else if (header.data_type == envi_header::float64)
-				return ((bil<double>*)file)->apply_mask(outfile, p);
+				((bil<double>*)file)->apply_mask(outfile, p, PROGRESS);
 			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);
+				((bip<float>*)file)->apply_mask(outfile, p, PROGRESS);
 			else if (header.data_type == envi_header::float64)
-				return ((bip<double>*)file)->apply_mask(outfile, p);
+				((bip<double>*)file)->apply_mask(outfile, p, PROGRESS);
 			else
 				std::cout << "ERROR: unidentified data type" << std::endl;
 		}
@@ -575,7 +574,7 @@ public:
 			std::cout << "ERROR: unidentified file type" << std::endl;
 			exit(1);
 		}
-		return false;
+		header.save(outfile + ".hdr");
 	}
 
 	/// Copies all spectra corresponding to nonzero values of a mask into a pre-allocated matrix of size (P x B)
--
libgit2 0.21.4