how to get the non zero location on a bitmap fingerprint image?

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I subtracted two fingerprint image and got the resultant image. Now I have to find the non zero location from the resultant image.

How can i get? Please help me for this.

This is my subtraction code.

C#

public static Bitmap subtractImage(Bitmap minuend, Bitmap deduction, int relativeX, int relativeY)
{
    Bitmap b = minuend;
    Bitmap b1 = deduction;

    Bitmap random = new Bitmap(256, 256, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

    Graphics g = Graphics.FromImage(random);
    g.DrawImage(b, new Point(0, 0));
    g.Dispose();

    Bitmap rec = new Bitmap(256, 256, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
    Graphics g1 = Graphics.FromImage(rec);
    g1.DrawImage(b1, new Point(0, 0));
    g1.Dispose();

    Bitmap result = new Bitmap(256, 256, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

    //  Bitmap r = new Bitmap(256, 256, , System.Drawing.Imaging.PixelFormat.Format24bppRgb, IntPtr.Size);
    //Bitmap rand=new Bitmap(pictureBox1.Image,256,256,System.Drawing.Imaging.PixelFormat.Format24bppRgb,IntPtr.Zero);
    //Bitmap rec = new Bitmap(pictureBox2.Image,System.Drawing.Imaging.PixelFormat.Format16bppGrayScale,IntPtr.Zero);
    //Bitmap result = new Bitmap(256, 256);

    Difference filter = new Difference(random);
    result = filter.Apply(rec);
    result.Save("d:\\result.bmp");
    return result;
}

[Edit member="Tadit"]
Added pre tags.
[/Edit]

Posted 31-Mar-14 18:46pm

Member 10663066

Updated 31-Mar-14 19:25pm

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

v3

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Comments

gggustafson 2-Apr-14 11:33am

Why are you using colored bitmaps? Convert to black/white. Why are your creating aliases (b and b1) for the originals? Use the originals. Where is your "difference" method?

Member 10663066 7-Apr-14 0:37am

The above coding is for subtracting two images,that i did.Now i want the code to find non zero location in an image. Here am using fingerprint images. Please help me i need this coding for project.

gggustafson 7-Apr-14 8:45am

What is "Difference"? What do you mean by "find non zero location in an image"?

Member 10663066 9-Apr-14 0:07am

My topic is "novel techniques in steganography using fingerprint images".
Description of my project is-

The system is working in two steps in general, the first is
hide the message, at the beginning, the sender will write or
upload his/her secret message to be hidden. Then the system
will get two fingerprint images: one is the receiver's
fingerprint image, and the second one is a random fingerprint
image. After that the system will convert it to bitmap type to
conduct the mathematical process on it. The system will
compare between the two images and subtract one from the
other to generate a new fingerprint image which is called
different fingerprint image, The system will extract from the
different fingerprint image the positions that are not equal to
zero, that means the differences positions. After that the
message will be prepared to the inserting process by
converting it from string type to bit type. The message will be inserted into the least significant bit of these extracted
positions of the random fingerprint image. The second step is
unhide the message, the receiver will get the fingerprint image
that hides the message from the sender via email, an instant
messaging file transfer, media storage devices, or by any way
they prefer. Then he/she will upload the fingerprint image that
hides the message, and his/her ID into the system, the system
will get his/her fingerprint image from the user fingerprint
image database and compares it with the fingerprint image that
hides the message to get the difference positions that hide the
message, then gets the message bits from the difference
positions least significant bits. Finally, it converts the bits into
string and displays it to the receiver.
i did the subtraction portion,now want to know the non zero location ofthe image to store the message.

gggustafson 9-Apr-14 0:39am

Thank you for the well-stated project description. But does not the difference contain what you want? Say the result of the difference for one byte, is 10011001. Are not the non-zero location the one's? So I ask again, what do you mean by the non-zero location in the image if it is not the difference?

Member 10663066 11-Apr-14 4:11am

ok. now i need code to hide a text message in the lsb of the pixel?
The text message will convert into bytes and then store in the lsb.how can i find the lsb of a pixel.? Help to find code for this.

gggustafson 11-Apr-14 12:43pm

A question: are you converting the 24bppRgb image to a 32bppArgb image before you process the image? Otherwise you cannot modify the image since there is no byte available. I am assuming that the alpha channel is not of interest and that its contents are not important. In that case, the A byte could be used for your text, except that it must be restored before the pixel is displayed. Read up on colors.

In 24bppRgb, the color DeepSkyBlue is 0,191,255 decimal or 00,BF,FF hexadecimal. In 32bppArgb, the same color is 0,0,191,255 or 00,00,BF,FF. The bits in the 32bppArgb value are

0000 0000 0000 0000 1011 1111 1111 1111

The first 8 bits is the alpha channel. Let's say we want to place the character 'G' (decimal 71; hexadecimal 47 in the alpha channel. Pictorially,

0000 0000 0000 0000 1011 1111 1111 1111
+ 0100 0111
= 0100 0111 0000 0000 1011 1111 1111 1111

To insert, assign 'G' to a long

int gee = ( int ) 'G';

Next you must align the character to the alpha channel byte. That is done by shifting 24 bits.

gee <<= 24;

gee now looks like

0100 0111 0000 0000 0000 0000 0000 0000

Lastly AND the two values and you will have inserted 'G' into the 32bppArgb value. To extract, AND the mask

1111 1111 0000 0000 0000 0000 0000 0000

with the 32bppArgb value and shift right 24 bits.

Hope that helps.

Member 10663066 16-Apr-14 4:53am

Thank you...for ur help

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