public static Bitmap[,] Grid(Bitmap img, uint rows, uint cols)
{
//Height must be divisible by rows & width must be divisible by cols, otherwise will require interpolation and will be much slower
if (img.Height % rows != 0 || img.Width % cols != 0)
{
throw new UnexpectedImageSizeException("Image height must be divisible by num rows and Image width must be divisible by num cols");
}
//Determine the number of Bytes Per pixel in this image
int bytesPerPixel = img.GetBitsPerPixel() / 8;
Bitmap[,] chars = new Bitmap[cols, rows];
//Lock image for read so we can access it with pointers
BitmapData imgData = img.LockBits(new Rectangle(0, 0, img.Width, img.Height),
ImageLockMode.ReadOnly, img.PixelFormat);
int colWidth = img.Width / (int)cols;
int rowHeight = img.Height / (int)rows;
unsafe
{
byte* ptrImgData = (byte*)imgData.Scan0;
for (int col = 0; col < chars.GetLength(0); col++)
{
for (int row = 0; row < chars.GetLength(1); row++)
{
//Make a new Bitmap to hold the char
Bitmap charBitmap = new Bitmap(colWidth, rowHeight, img.PixelFormat);
//Lock image for write so we can write to it
BitmapData charData = charBitmap.LockBits(new Rectangle(0, 0, charBitmap.Width, charBitmap.Height),
ImageLockMode.WriteOnly, charBitmap.PixelFormat);
byte* ptrCharData = (byte*)charData.Scan0;
//Loop over each pixel in this char to be extracted
for (int i = 0; i < colWidth; i++)
{
for(int j = 0; j < rowHeight; j++)
{
int imgOffset = ((row * rowHeight) + j) * imgData.Stride + (((col * colWidth) + i) * bytesPerPixel);
int charOffset = (j * charData.Stride) + (i * bytesPerPixel);
//Copy the bytes for this pixel
for(int k = 0; k < bytesPerPixel; k++)
{
ptrCharData[charOffset + k] = ptrImgData[imgOffset + k];
}
}
}
charBitmap.UnlockBits(charData);
chars[col, row] = charBitmap;
}
}
}
img.UnlockBits(imgData);
return chars;
}
public static Bitmap[,] Segment(Bitmap img, Segmentation segmentation)
{
//Validation: Check that the Bitmap has the dimensions listed in the Segmentation
if(img.Width != segmentation.Width || img.Height != segmentation.Height)
{
throw new ArgumentException("Bitmap dimensions must match Segmentation dimensions");
}
//Determine the number of Bytes Per pixel in this image
int bytesPerPixel = img.GetBitsPerPixel() / 8;
Bitmap[,] chars = new Bitmap[segmentation.NumCols, segmentation.NumRows];
//Lock the image for read so we can access it with pointers
BitmapData imgData = img.LockBits(new Rectangle(0, 0, img.Width, img.Height),
ImageLockMode.ReadOnly, img.PixelFormat);
unsafe
{
byte* ptrImageData = (byte*)imgData.Scan0;
for (int col = 0; col < chars.GetLength(0); col++)
{
for(int row = 0; row < chars.GetLength(1); row++)
{
//Get the start & end indices of this char based on the segmentation points
int colStart = col == 0 ? 0 : segmentation.Cols[col - 1]; //If this is the first col, it starts at zero. Otherwise where the previous col ended
int colEnd = col == chars.GetLength(0) - 1 ? segmentation.Width - 1 : segmentation.Cols[col]; //If this is the last col, ends at width. Otherwise at the segmentation index
int rowStart = row == 0 ? 0 : segmentation.Rows[row - 1]; //If this is the first row, it starts at zero. Otherwise where the previous row ended
int rowEnd = row == chars.GetLength(1) - 1 ? segmentation.Height - 1 : segmentation.Rows[row]; //If this is the last row, ends at height. Otherwise at the segmentation index
//Make a new Bitmap to hold the char
Bitmap charBitmap = new Bitmap(colEnd + 1 - colStart, rowEnd + 1 - rowStart, img.PixelFormat);
//Lock image for write so we can write to it
BitmapData charData = charBitmap.LockBits(new Rectangle(0, 0, charBitmap.Width, charBitmap.Height),
ImageLockMode.WriteOnly, charBitmap.PixelFormat);
byte* ptrCharData = (byte*)charData.Scan0;
//Loop over each pixel in this char to be extracted
for(int pxCol = colStart; pxCol <= colEnd; pxCol++)
{
for(int pxRow = rowStart; pxRow <= rowEnd; pxRow++)
{
int imgOffset = (pxRow * imgData.Stride) + (pxCol * bytesPerPixel);
int charOffset = ((pxRow - rowStart) * charData.Stride) + ((pxCol - colStart) * bytesPerPixel);
//Copy the bytes for this pixel
for(int i = 0; i < bytesPerPixel; i++)
{
ptrCharData[charOffset + i] = ptrImageData[imgOffset + i];
}
}
}
charBitmap.UnlockBits(charData);
chars[col, row] = charBitmap;
}
}
}
img.UnlockBits(imgData);
return chars;
}
