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    <p>You really need to use <a href="http://msdn.microsoft.com/en-us/library/5ey6h79d.aspx" rel="nofollow"><code>LockBits</code></a> instead of <code>GetPixel</code> and <code>SetPixel</code>. </p> <p>So you create a <code>BitmapData</code> object that contains all of the pixel data:</p> <pre><code>// lock the input bitmap's bits System.Drawing.Imaging.BitmapData bmpData = original.LockBits(new Rectangle(0, 0, original.Width, original.Height), System.Drawing.Imaging.ImageLockMode.Read, original.PixelFormat); </code></pre> <p>Then, you can get the address of the first scan line (i.e. the first row of pixels):</p> <pre><code>IntPtr ptr = bmpData.Scan0; </code></pre> <p>Now you have two choices. If you're happy to mark your function as <code>unsafe</code> then you can access the pixels directly using pointer arithmetic, like this</p> <pre><code>byte* pPixels = (byte*)ptr.ToPointer(); </code></pre> <p>which gives you a pointer to the first byte of an RGB pixel (assuming 24bpp). Then you can access an individual pixel at <code>(x,y)</code> using pointer arithmetic. First you determine how many bytes per pixel (if you don't already know)</p> <pre><code>int nBytesPerPixel = Image.GetPixelFormatSize(original.PixelFormat) / 8; </code></pre> <p>Then calculate the index to the pixel you want</p> <pre><code>byte* pPixelAtXY = pPixels + (y * bmpData.Stride) + (x * nBytesPerPixel); </code></pre> <p>This gives you <code>unsafe</code> access to the pixels in a <code>Bitmap</code> which you can do for the input and output bitmaps for fastest speed. Note that to use unsafe code, you need to <a href="http://msdn.microsoft.com/en-us/library/chfa2zb8%28v=vs.100%29.aspx" rel="nofollow">mark your function as unsafe</a> and <a href="http://msdn.microsoft.com/en-us/library/ct597kb0%28v=vs.100%29.aspx" rel="nofollow">edit your project properties</a>.</p> <p>If you don't want to use <code>unsafe</code> code, you can still speed things up by copying all of the pixel data to a <code>byte</code> array before processing and then copy it back afterwards. As the MSDN example showed</p> <pre><code>// 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 &lt; rgbValues.Length; counter += 3) rgbValues[counter] = 255; // Copy the RGB values back to the bitmap System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes); </code></pre> <p>Whichever method you use, when you have finished with the pixel data, you <em>must</em> release it using <code>UnlockBits</code></p> <pre><code>original.UnlockBits(bmpData); </code></pre>
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    1. COcould you give a complete source code, i've try it but i get any errors.
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    2. CO@user1442032 If you edit your question to show your new code, then we can see what's wrong.
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