diff --git a/cs677/pa3/chryseobacterium.bmp b/cs677/pa3/chryseobacterium.bmp
new file mode 100644
index 0000000..a62a954
Binary files /dev/null and b/cs677/pa3/chryseobacterium.bmp differ
diff --git a/cs677/pa3/edge-detect-display b/cs677/pa3/edge-detect-display
new file mode 100755
index 0000000..40df24a
--- /dev/null
+++ b/cs677/pa3/edge-detect-display
@@ -0,0 +1,11 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+my @args = @ARGV;
+my $edgesFileName = $args[$#args];
+$edgesFileName =~ s/\.bmp$/-edges.bmp/i;
+
+system('./edge-detect', @args);
+system('display', $edgesFileName);
diff --git a/cs677/pa3/edge-detect.cc b/cs677/pa3/edge-detect.cc
index 29749c8..88dbe9f 100644
--- a/cs677/pa3/edge-detect.cc
+++ b/cs677/pa3/edge-detect.cc
@@ -1,18 +1,62 @@
 
 #include <iostream>
 #include <string.h>
+#include <stdlib.h>
 #include "BMP.h"
 using namespace std;
 
+void usage(const char * progName)
+{
+    cout << "Usage: " << progName << " [options] <input-BMP-file>" << endl;
+    cout << "  Options:" << endl;
+    cout << "    -l threshold_level : set threshold level" << endl;
+    exit(42);
+}
+
 int main(int argc, char * argv[])
 {
-    BMP readfrom(argv[1]);
-    unsigned char * data = new unsigned char[readfrom.getWidth() * readfrom.getHeight() * 3];
-    readfrom.read(data);
+    int argi;
+    string inputFileName;
+    string outputFileName;
+    unsigned int threshold_level = 60;
 
-    BMP bmp_create((string(argv[1], strlen(argv[1]) - 4) + "-2.bmp").c_str(),
-                   readfrom.getWidth(),
-                   readfrom.getHeight(),
-                   data);
+    if (argc < 2)
+        usage(argv[0]);
+
+    for (argi = 0; argi < argc; argi++)
+    {
+        if (!strcmp(argv[argi], "-l"))
+        {
+            if (argi >= argc - 1)
+                usage(argv[0]);
+            argi++;
+            threshold_level = atoi(argv[argi]);
+        }
+        else
+        {
+            inputFileName = argv[argi];
+            outputFileName = string(argv[argi], strlen(argv[argi]) - 4);
+            outputFileName += "-edges.bmp";
+        }
+    }
+
+
+    BMP inputImage(inputFileName.c_str());
+    unsigned char * data =
+        new unsigned char[inputImage.getWidth() * inputImage.getHeight() * 3];
+    inputImage.read(data);
+
+    unsigned char * data_ptr = data;
+    for (int i = 0; i < inputImage.getWidth() * inputImage.getHeight(); i++)
+    {
+        *data_ptr++ = 0;
+        *data_ptr++ = 0;
+        data_ptr++;
+    }
+
+    BMP edges(outputFileName.c_str(),
+              inputImage.getWidth(),
+              inputImage.getHeight(),
+              data);
     delete[] data;
 }