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I am trying to implement image invert filter in C#.
For that I am using pointer in C# but there occur an error in line no. 20 which is Error "Unsafe code may only appear if compiling with /unsafe".

So I am unable to remove this error.

Please help me.
Thanks in advance.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Drawing.Imaging;

namespace DIP
    class BitmapFilter
        public static bool Invert(Bitmap b)
            BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);

            int stride = bmData.Stride;
            System.IntPtr Scan0 = bmData.Scan0;

                byte* p = (byte*)(void*)Scan0;

                int nOffset = stride - b.Width * 3;
                int nWidth = b.Width * 3;

                for (int y = 0; y < b.Height; ++y)
                    for (int x = 0; x < nWidth; ++x)
                        p[0] = (byte)(1000 + p[0]);
                    p += nOffset;
            return true;
Updated 13-Feb-18 22:19pm

1 solution

You have to check the "Allow unsafe code" checkbox in the project's properties.
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