What is the difference between System.Drawing.bitmap and System.Drawing.Imaging.bitmapdata in C#?
How to convert them to each other?
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2 Answers
System.Drawing.Bitmap is an actual bitmap object. You can use it to draw to using a Graphics instance obtained from it, you can display it on the screen, you can save the data to a file, etc.
The System.Drawing.Imaging.BitmapData class is a helper object used when calling the Bitmap.LockBits() method. It contains information about the locked bitmap, which you can use to inspect the pixel data within the bitmap.
You can't really "convert" between the two per se, as they don't represent the same information. You can obtain a BitmapData object from a Bitmap object simply by calling LockBits(). If you have a BitmapData object from some other Bitmap object, you can copy that data to a new Bitmap object by allocating one with the same format as the original, calling LockBits on that one too, and then just copying the bytes from one to the other.
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Convert bitmap to bitmap data. Also refer this link
Private void LockUnlockBitsExample(PaintEventArgs e) {
// Create a new bitmap.
Bitmap bmp = new Bitmap("c:\\fakePhoto.jpg");
// Lock the bitmap's bits.
Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
System.Drawing.Imaging.BitmapData bmpData = bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, bmp.PixelFormat);
// Get the address of the first line.
IntPtr ptr = bmpData.Scan0;
// Declare an array to hold the bytes of the bitmap.
int bytes = Math.Abs(bmpData.Stride) * bmp.Height;
byte[] rgbValues = new byte[bytes];
// Copy the RGB values into the array.
System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes);
// Set every third value to 255. A 24bpp bitmap will look red.
for (int counter = 2; counter < rgbValues.Length; counter += 3) rgbValues[counter] = 255;
// Copy the RGB values back to the bitmap
System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes);
// Unlock the bits.
bmp.UnlockBits(bmpData);
// Draw the modified image.
e.Graphics.DrawImage(bmp, 0, 150);
}
