diff --git a/cs677/pa3/BMP.cc b/cs677/pa3/BMP.cc
index 7753df4..6682b36 100644
--- a/cs677/pa3/BMP.cc
+++ b/cs677/pa3/BMP.cc
@@ -8,12 +8,12 @@
 #include <iostream>
 using namespace std;
 
-BMP::BMP(char * fileName)
+BMP::BMP(const char * fileName)
 {
     open(fileName);
 }
 
-BMP::BMP(char * fileName, int width, int height, unsigned char * data)
+BMP::BMP(const char * fileName, int width, int height, unsigned char * data)
 {
     create(fileName, width, height, data);
 }
@@ -24,7 +24,7 @@ BMP::~BMP()
         close();
 }
 
-bool BMP::open(char * fileName)
+bool BMP::open(const char * fileName)
 {
     m_fp = fopen(fileName, "r+");
     if (m_fp != NULL)
@@ -43,7 +43,7 @@ bool BMP::open(char * fileName)
     return (m_fp != NULL);
 }
 
-bool BMP::create(char * fileName, int width, int height, unsigned char * data)
+bool BMP::create(const char * fileName, int width, int height, unsigned char * data)
 {
     m_fp = fopen(fileName, "w+");
     if (m_fp != NULL)
@@ -102,7 +102,7 @@ void BMP::read(unsigned char * buf)
         fseek(m_fp,
               (m_header.offset != 0
                   ? m_header.offset
-                  : sizeof(m_header) + sizeof(m_info))
+                  : sizeof(m_header) + sizeof(m_info)),
               SEEK_SET);
         unsigned char * data_ptr = buf + row_data_bytes * (m_info.height - 1);
         for (int i = 0; i < m_info.height; i++)
diff --git a/cs677/pa3/BMP.h b/cs677/pa3/BMP.h
index fb93836..e4ac9bd 100644
--- a/cs677/pa3/BMP.h
+++ b/cs677/pa3/BMP.h
@@ -31,8 +31,8 @@ public:
         int num_important_colors;
     } __attribute__ ((packed)) info_t;
 
-    BMP(char * fileName);
-    BMP(char * fileName, int width, int height, unsigned char * data);
+    BMP(const char * fileName);
+    BMP(const char * fileName, int width, int height, unsigned char * data);
     ~BMP();
     void    read(unsigned char * buf);
     int     getWidth() { return m_info.width; }
@@ -43,7 +43,7 @@ private:
     header_t    m_header;
     info_t      m_info;
 
-    bool    open(char * fileName);
-    bool    create(char * fileName, int width, int height, unsigned char * data);
+    bool    open(const char * fileName);
+    bool    create(const char * fileName, int width, int height, unsigned char * data);
     void    close();
 };
diff --git a/cs677/pa3/edge-detect.cc b/cs677/pa3/edge-detect.cc
index 8b5cb41..29749c8 100644
--- a/cs677/pa3/edge-detect.cc
+++ b/cs677/pa3/edge-detect.cc
@@ -1,9 +1,18 @@
 
 #include <iostream>
+#include <string.h>
 #include "BMP.h"
 using namespace std;
 
 int main(int argc, char * argv[])
 {
-    cout << "edge-detect" << endl;
+    BMP readfrom(argv[1]);
+    unsigned char * data = new unsigned char[readfrom.getWidth() * readfrom.getHeight() * 3];
+    readfrom.read(data);
+
+    BMP bmp_create((string(argv[1], strlen(argv[1]) - 4) + "-2.bmp").c_str(),
+                   readfrom.getWidth(),
+                   readfrom.getHeight(),
+                   data);
+    delete[] data;
 }