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

fix remaining 1px white space at the top and left

    public Bitmap Crop(Bitmap bitmap)
    {
        int w = bitmap.Width;
        int h = bitmap.Height;

        Func IsAllWhiteRow = row =>
        {
            for (int i = 0; i < w; i++)
            {
                if (bitmap.GetPixel(i, row).R != 255)
                {
                    return false;
                }
            }
            return true;
        };

        Func IsAllWhiteColumn = col =>
        {
            for (int i = 0; i < h; i++)
            {
                if (bitmap.GetPixel(col, i).R != 255)
                {
                    return false;
                }
            }
            return true;
        };

        int leftMost = 0;
        for (int col = 0; col < w; col++)
        {
            if (IsAllWhiteColumn(col)) leftMost = col + 1;
            else break;
        }

        int rightMost = w - 1;
        for (int col = rightMost; col > 0; col--)
        {
            if (IsAllWhiteColumn(col)) rightMost = col - 1;
            else break;
        }

        int topMost = 0;
        for (int row = 0; row < h; row++)
        {
            if (IsAllWhiteRow(row)) topMost = row + 1;
            else break;
        }

        int bottomMost = h - 1;
        for (int row = bottomMost; row > 0; row--)
        {
            if (IsAllWhiteRow(row)) bottomMost = row - 1;
            else break;
        }

        if (rightMost == 0 && bottomMost == 0 && leftMost == w && topMost == h)
        {
            return bitmap;
        }

        int croppedWidth = rightMost - leftMost + 1;
        int croppedHeight = bottomMost - topMost + 1;

        try
        {
            Bitmap target = new Bitmap(croppedWidth, croppedHeight);
            using (Graphics g = Graphics.FromImage(target))
            {
                g.DrawImage(bitmap,
                    new RectangleF(0, 0, croppedWidth, croppedHeight),
                    new RectangleF(leftMost, topMost, croppedWidth, croppedHeight),
                    GraphicsUnit.Pixel);
            }
            return target;
        }
        catch (Exception ex)
        {
            throw new Exception(string.Format("Values are top={0} bottom={1} left={2} right={3}", topMost, bottomMost, leftMost, rightMost), ex);
        }
    }