Remove surrounding whitespace from an image

Question

I have a block of product images we received from a customer. Each product image is a picture of something and it was taken with a white background. I would like to crop a

Answer 1

public void TrimImage() {
    int threshhold = 250;


    int topOffset = 0;
    int bottomOffset = 0;
    int leftOffset = 0;
    int rightOffset = 0;
    Bitmap img = new Bitmap(@"e:\Temp\Trim_Blank_Image.png");


    bool foundColor = false;
    // Get left bounds to crop
    for (int x = 1; x < img.Width && foundColor == false; x++)
    {
        for (int y = 1; y < img.Height && foundColor == false; y++)
        {
            Color color = img.GetPixel(x, y);
            if (color.R < threshhold || color.G < threshhold || color.B < threshhold)
                foundColor = true;
        }
        leftOffset += 1;
    }


    foundColor = false;
    // Get top bounds to crop
    for (int y = 1; y < img.Height && foundColor == false; y++)
    {
        for (int x = 1; x < img.Width && foundColor == false; x++)
        {
            Color color = img.GetPixel(x, y);
            if (color.R < threshhold || color.G < threshhold || color.B < threshhold)
                foundColor = true;
        }
        topOffset += 1;
    }


    foundColor = false;
    // Get right bounds to crop
    for (int x = img.Width - 1; x >= 1 && foundColor == false; x--)
    {
        for (int y = 1; y < img.Height && foundColor == false; y++)
        {
            Color color = img.GetPixel(x, y);
            if (color.R < threshhold || color.G < threshhold || color.B < threshhold)
                foundColor = true;
        }
        rightOffset += 1;
    }


    foundColor = false;
    // Get bottom bounds to crop
    for (int y = img.Height - 1; y >= 1 && foundColor == false; y--)
    {
        for (int x = 1; x < img.Width && foundColor == false; x++)
        {
            Color color = img.GetPixel(x, y);
            if (color.R < threshhold || color.G < threshhold || color.B < threshhold)
                foundColor = true;
        }
        bottomOffset += 1;
    }


    // Create a new image set to the size of the original minus the white space
    //Bitmap newImg = new Bitmap(img.Width - leftOffset - rightOffset, img.Height - topOffset - bottomOffset);

    Bitmap croppedBitmap = new Bitmap(img);
    croppedBitmap = croppedBitmap.Clone(
                    new Rectangle(leftOffset - 3, topOffset - 3, img.Width - leftOffset - rightOffset + 6, img.Height - topOffset - bottomOffset + 6),
                    System.Drawing.Imaging.PixelFormat.DontCare);


    // Get a graphics object for the new bitmap, and draw the original bitmap onto it, offsetting it do remove the whitespace
    //Graphics g = Graphics.FromImage(croppedBitmap);
    //g.DrawImage(img, 1 - leftOffset, 1 - rightOffset);
    croppedBitmap.Save(@"e:\Temp\Trim_Blank_Image-crop.png", ImageFormat.Png);
}

I have got code from other post in ms, but that has bugs, I have changed something, now it works good.

The post from http://msm2020-sc.blogspot.com/2013/07/c-crop-white-space-from-around-image.html