Apply median filter to fingerprint image

Question

5.00/5 (1 vote)

See more:

Hey friends please help me in coding median filter to remove noise from the fingerprint image using pointers. I have done this much...

C#

byte* imgPtr = (byte*)(void*)(data.Scan0);
               byte* src = (byte*)(void*)(data.Scan0);
               int sOffset = stride - 9;
               int nOffset = stride - image.Width * 3;
               int i,j,v = 0,h=0;
               for ( i = 0; i < image.Width; i++)
               {
                   for ( j = 1; j < image.Height; j++)
                   {
                       imgPtr = src;
                       for(x=0;x<3;x++)
                       {
                           for (y = 0; y <3; y++)
                           {
                               red[x, y] = imgPtr[0];
                               r1[h] = imgPtr[0];
                               green[x, y] = imgPtr[1];
                               g1[h] = imgPtr[1];
                               blue[x, y] = imgPtr[2];
                               b1[h] = imgPtr[2];
                               imgPtr += 3;
                               h++;
                           }
                           imgPtr += sOffset;
                       }
                       src += 3;
                               Array.Sort(r1);
                               r[v] = r1[4];
                               Array.Sort(g1);
                                 g[v] = g1[4];
                               Array.Sort(b1);
                               b[v] = b1[4];
                               //MPtr += 3;
                               v++;

Posted 4-Mar-11 6:27am

Noel3090

Updated 4-Mar-11 7:04am

Henry Minute

v2

Add a Solution

Comments

Sergey Alexandrovich Kryukov 4-Mar-11 15:18pm

You have done this, and...
--SA

sairam.bhat 5-Apr-11 0:55am

thank you good question i upvoted +5

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

sairam.bhat · Accepted Answer · 2011-03-04T19:02:00

Noise Reduction of an Image in C# using Median Filters

VB

One of the main issues when trying to do image processing is the simple fact that images usually contain some degree of noise. This noise can in turn cause issues. For instance if you're doing edge detection, a spot on the image may cause the algorithm to detect edges that it shouldn't. One of the easiest ways to fix this issue is to use a median filter on an image. Unlike box blurs and gaussian blurs, we're not looking for the average of the pixels. In the case of a median filter, we're looking for the median (sort the values, take the one in the middle). We're still looking at a set of pixels around each pixel but we're simply taking the median instead of the mean.  The advantage of this approach is that it keeps the edges of an image but simply degrades the details a bit, unlike a box blur which will slowly bleed the edges.
Unfortunately in C# there is no built in function to do this (or at least none that I'm aware of) and as such I wrote code to accomplish it and as always I'm sharing it with you:

XML

1: public static Bitmap MedianFilter(Bitmap Image, int Size)
  2: {
  3:     System.Drawing.Bitmap TempBitmap = Image;
  4:     System.Drawing.Bitmap NewBitmap = new System.Drawing.Bitmap(TempBitmap.Width, TempBitmap.Height);
  5:     System.Drawing.Graphics NewGraphics = System.Drawing.Graphics.FromImage(NewBitmap);
  6:     NewGraphics.DrawImage(TempBitmap, new System.Drawing.Rectangle(0, 0, TempBitmap.Width, TempBitmap.Height), new System.Drawing.Rectangle(0, 0, TempBitmap.Width, TempBitmap.Height), System.Drawing.GraphicsUnit.Pixel);
  7:     NewGraphics.Dispose();
  8:     Random TempRandom = new Random();
  9:     int ApetureMin = -(Size / 2);
 10:     int ApetureMax = (Size / 2);
 11:     for (int x = 0; x < NewBitmap.Width; ++x)
 12:     {
 13:         for (int y = 0; y < NewBitmap.Height; ++y)
 14:         {
 15:             List<int> RValues = new List<int>();
 16:             List<int> GValues = new List<int>();
 17:             List<int> BValues = new List<int>();
 18:             for (int x2 = ApetureMin; x2 < ApetureMax; ++x2)
 19:             {
 20:                 int TempX = x + x2;
 21:                 if (TempX >= 0 && TempX < NewBitmap.Width)
 22:                 {
 23:                     for (int y2 = ApetureMin; y2 < ApetureMax; ++y2)
 24:                     {
 25:                         int TempY = y + y2;
 26:                         if (TempY >= 0 && TempY < NewBitmap.Height)
 27:                         {
 28:                             Color TempColor = TempBitmap.GetPixel(TempX, TempY);
 29:                             RValues.Add(TempColor.R);
 30:                             GValues.Add(TempColor.G);
 31:                             BValues.Add(TempColor.B);
 32:                         }
 33:                     }
 34:                 }
 35:             }
 36:             RValues.Sort();
 37:             GValues.Sort();
 38:             BValues.Sort();
 39:             Color MedianPixel = Color.FromArgb(RValues[RValues.Count / 2],
 40:                 GValues[GValues.Count / 2],
 41:                 BValues[BValues.Count / 2]);
 42:             NewBitmap.SetPixel(x, y, MedianPixel);
 43:         }
 44:     }
 45:     return NewBitmap;
 46: }