Manipulating images at pixel level in c# to decode it in to text info if it contains?

Question

How can we get the info from an image if it contains by calculating the no of pixels and there arrangement.

Answer 1

You can make use of the Bitmap class in .Net

Here a nice example: Image Processing for Dummies with C# and GDI+ Part 1 - Per Pixel Filters

Also the following StackOverflow (Question: How to manipulate images at pixel level in C#) provides already an answer :D

Answer 2

You can use the Bitmap (System.Drawing) class. Then, to manipulate pixels, use the methods GetPixel() and SetPixel(). But if you want a faster access to the pixels, read this article: Using the LockBits method to access image data by Bob Powell that exploits pointers, compiling with unsafe code.

Answer 3

Here's an example of manipulating pixel data using pointers.

unsafe
{
int red, blue, green;
editImage = new Bitmap("image.jpg");
editWidth = editImage.Width;
editHeight = editImage.Height;
data = editImage.LockBits(new Rectangle(0, 0, editWidth, editHeight), 
ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
byte* dataPtr = (byte*)data.Scan0;
h = trackBar1.Value / 60.0;
D = 1 - Math.Abs((h % 2) - 1);

if (h >= 0 && h < 1)
{
    for (int i = 0; i < editHeight; i++)
    {
        offsetStride = i * data.Stride;
        for (int j = 0; j < editWidth; j++)
        {
            blue = dataPtr[(j * 3) + offsetStride];
            green = dataPtr[(j * 3) + offsetStride + 1];
            red = dataPtr[(j * 3) + offsetStride + 2];

            if (green > blue) max = green;
            else max = blue;
            if (red > max) max = red;

            if (green < blue) min = green;
            else min = blue;
            if (red < min) min = red;

            s = (max == 0) ? 0 : 1d - (1d * min / max);
            v = max / 255d;

            C = v * s;
            X = C * D;
            E = v - C;

            dataPtr[(j * 3) + offsetStride] = (byte)(min);
            dataPtr[(j * 3) + offsetStride + 1] = (byte)((X + E) * 255);
            dataPtr[(j * 3) + offsetStride + 2] = (byte)(max);
        }
    }
}
}

This just changes the hue of an image. For any reasonably large image > 100x100 pixels, don't bother using GetPixel or SetPixel unless performance doesn't matter.