/// <summary>
/// Decode a QRCode
/// </summary>
/// <param name="img">image containing the QRCode</param>
private QRCode(MyImage img)
{
// Copy image on this object
image = new Pixel[img.image.GetLength(0), img.image.GetLength(1)];
for (int i = 0; i < image.GetLength(0); i++)
{
for (int j = 0; j < image.GetLength(1); j++)
{
image[i, j] = new Pixel(img.image[i, j]);
}
}
/* https://www.researchgate.net/publication/221337868_Fast_QR_Code_Detection_in_Arbitrarily_Acquired_Images */
//Assume image is flat on the surface
//Find the size of a finder and the size of a code to determine the version
//and the size of a bit to be accurate while reading
// plus save the start index of QRCode;
// Different size horizontal and vertical (if image is warped
int sizeOfFinderHorizontal = 0;
int sizeOfCodeHorizontal = 0;
int sizeOfFinderVertical = 0;
int sizeOfCodeVertical = 0;
bool b = true;
int line = 0;
int column = 0;
int startLine = 0;
int startColumn = 0;
//Searching
while (b)
{
column = 0;
while (column < image.GetLength(1) && !image[line, column].isCloseToBlack)
{
column++;
}
startColumn = column;
startLine = line;
// For horizontal size
while (column < image.GetLength(1) && image[startLine, column].isCloseToBlack)
{
b = false;
sizeOfFinderHorizontal++;
column++;
}
// For Vertical size
while (!b && line < image.GetLength(0) && image[line, startColumn].isCloseToBlack)
{
sizeOfFinderVertical++;
line++;
}
if (!b)
{
// Horizontal size
for (int j = image.GetLength(1) - 1; j >= 0 && sizeOfCodeHorizontal == 0; j--)
{
if (image[startLine, j].isCloseToBlack)
{
sizeOfCodeHorizontal = j - startColumn;
}
}
// Vertical Size
for (int j = image.GetLength(0) - 1; j >= 0 && sizeOfCodeVertical == 0; j--)
{
if (image[j, startColumn].isCloseToBlack)
{
sizeOfCodeVertical = j - startLine;
}
}
}
line++;
}
//Compute the size of a bit (finder is 7 pixels wide)
int bitSizeHorizontal = sizeOfFinderHorizontal / 7;
int bitSizeVertical = sizeOfFinderVertical / 7;
int approxSize = sizeOfCodeHorizontal / bitSizeHorizontal;
//Determine the version of QR based on the size
if (approxSize < 23)
{
type = 1;
}
else
{
type = 2;
}
//Now read the QRCode but first Draw the Canvas
DrawCanvas();
//Read DAta
string messageBits = ReadData(bitSizeHorizontal, bitSizeVertical, startLine, startColumn);
// Get rid of the last seven bits if type 2
if (type == 2)
{
messageBits = messageBits.Substring(0, 352);
}
Console.WriteLine(messageBits);
// Get The Error count
int eccCount = 7 * 8;
if (type == 2)
{
eccCount = 10 * 8;
}
//Split error bits and message bits
string errorBits = messageBits.Substring(messageBits.Length - eccCount, eccCount);
messageBits = messageBits.Substring(0, messageBits.Length - eccCount);
// Decode with Reed Solomon Algorithm
byte[] messageBytes = BitsToByte(messageBits);
byte[] errorBytes = BitsToByte(errorBits);
byte[] finalMessage = ReedSolomonAlgorithm.Decode(messageBytes, errorBytes, ErrorCorrectionCodeType.QRCode);
messageBits = ByteToBit(finalMessage);
// Assume the image is alphanumeric and get rid of the length
messageBits = messageBits.Substring(4, messageBits.Length - 4);
Decode_Message(messageBits);
}
