Storing fingerprint images using double datatype

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How do I store a fingerprint image using a double datatype instead of varbinary in sql server using c# as the front end.

Posted 18-Oct-10 10:19am

Ogorgirl

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AspDotNetDev 18-Oct-10 16:27pm

Why would you want to?

Ogorgirl 18-Oct-10 16:30pm

I am having a difficulty trying to compare the images in hexadecimal(varbinary). I decided to use Double which will be easier to compare

AspDotNetDev 18-Oct-10 16:42pm

Really depends on what you want (e.g., if you are storing raw pixel data or a compressed image file), but I can almost guarantee you that using a double datatype is going to be difficult and silly. If you don't want to use varbinary, use integer instead. Or, even better, figure out how to properly use varbinary.

Ogorgirl 18-Oct-10 17:06pm

Thanks. I'm finding it difficult to compare Hexadecimals cos it stores it as Hexadecimal when I use varbinary.. Fingerprint images never have same hex value, it is difficult converting it and then matching it with the new fingerprint hex value to be stored. I don't know if u understand what i mean?

AspDotNetDev 18-Oct-10 19:19pm

Not really. When you get the data back to C#, you do not have it in a "hexadecimal" form. You probably get a byte array. Each byte stores 8-bits (or 256 combinations). Assuming you pass it in as a byte array and you get it back as a byte array, I don't see what the problem is. Perhaps if you update your question with a very specific example of a problem you are encountering, and include code, we can help you.

Ogorgirl 18-Oct-10 19:24pm

I have something like this

SqlCommand newSqlCommand = new SqlCommand("SELECT * FROM Attendance", myConnection);
SqlCommand anewSqlCommand = new SqlCommand("SELECT FPrint_Image FROM Student", myConnection);
SqlCommand abnewSqlCommand = new SqlCommand("SELECT FPrint_ImageB FROM Student", myConnection);
//To get a student number from the student table
SqlCommand studidSql =
new SqlCommand("SELECT Student_Id FROM Student WHERE FPrint_Image NOT IN FPrint_ImageB", myConnection);
newSqlCommand.CommandType = CommandType.Text;
SqlCommand acnewSqlCommand = new SqlCommand("SELECT FPrint_Image FROM Attendance", myConnection);
acnewSqlCommand.CommandType = CommandType.Text;
Hexstring = (String)anewSqlCommand.ExecuteScalar();
Hexstring2 = (String)abnewSqlCommand.ExecuteScalar();
HexstringV = (String)acnewSqlCommand.ExecuteScalar();

newbyte = byte.Parse(Hexstring, System.Globalization.NumberStyles.HexNumber);
newbyte2 = byte.Parse(Hexstring2, System.Globalization.NumberStyles.HexNumber);
newbyteV = byte.Parse(HexstringV, System.Globalization.NumberStyles.HexNumber);

//newbyte = (Byte)m_Regmin1;
m_Regmin1 = new Byte[newbyte] ;
m_Regmin2 = new Byte[newbyte2];
m_Vrfy = new Byte[newbyteV];

iError = m_FPM.MatchTemplate(m_Regmin1, m_Vrfy, secu_level, ref matched);
iError = m_FPM.MatchTemplate(m_Regmin2, m_Vrfy, secu_level, ref matched1);
if (iError == (Int32)SGFPMError.ERROR_NONE)
{
if (matched & matched1)
{
StatusBar.Text = "Verification Success";
}
else
StatusBar.Text = "Verification Failed";
}
else
DisplayError("GetMatchingScore()", iError);

Sergey Alexandrovich Kryukov 17-Dec-10 2:44am

The root problem is here: how do you compare images and why? I mean, how do you define comparison?
I hope, you're not talking about image recognition itself?

Ogorgirl 4-Oct-12 7:35am

That's exactly what I'm talking about in Fingerprint images. Not to worry! all sorted many years back now.

Sergey Alexandrovich Kryukov 4-Oct-12 10:44am

That's exactly right, but it does not mean it could be easily done from scratch.
Good luck,
--SA

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