C# - Remove Bitmap padding

Question

I was wondering if there\'s a way in order to remove the padding generated by the 24 bit Bitmap for each scan line.

What I mean is like this :

Original [Pure

Answer 1

I created an Extension mehtod to AutoCrop images.I look for the first filed pixel on Left, Top, Right and Bottom. Then calculate a rectangle. Using Graphics.DrawImage you can specify the cropped region via the source and new Rectangle.

public static Bitmap AutoCrop(this Bitmap bitmap)
    {
        int leftSHift = 0;
        int topShift = 0;
        int rightShift = 0;
        int bottomShift = 0;

        // left Shift
        for (int widthX = 0; widthX < bitmap.Width; widthX++)
        {
            for (int heightY = 0; heightY < bitmap.Height; heightY++)
            {
                Color c = bitmap.GetPixel(widthX, heightY);
                if (!c.Name.Equals("0"))
                {
                    leftSHift = widthX;
                    break;
                }

            }
            if (!leftSHift.Equals(0))
                break;
        }

        // Top Shift
        for (int widthX = 0; widthX < bitmap.Height; widthX++)
        {
            for (int heightY = 0; heightY < bitmap.Width - 1; heightY++)
            {
                Color c = bitmap.GetPixel(heightY, widthX);
                if (!c.Name.Equals("0"))
                {
                    topShift = widthX;
                    break;
                }
            }
            if (!topShift.Equals(0))
                break;
        }

        // Right Shift
        for (int heightX = bitmap.Width - 1; heightX >= 0; heightX--)
        {
            for (int widthY = 0; widthY < bitmap.Height; widthY++)
            {
                Color c = bitmap.GetPixel(heightX, widthY);
                if (!c.Name.Equals("0"))
                {
                    rightShift = heightX;
                    break;
                }
            }
            if (!rightShift.Equals(0))
                break;
        }

        //Bottom Shift.
        for (int heightX = bitmap.Height - 1; heightX >= 0; heightX--)
        {
            for (int widthY = 0; widthY < bitmap.Width - 1; widthY++)
            {
                Color c = bitmap.GetPixel(widthY, heightX);
                if (!c.Name.Equals("0"))
                {
                    bottomShift = heightX;
                    break;
                }
            }
            if (!bottomShift.Equals(0))
                break;
        }

        Rectangle cropRect = new Rectangle
            (
            leftSHift + 1,
            topShift,
            bitmap.Width - (leftSHift + (bitmap.Width - rightShift)),
            bitmap.Height - (topShift + (bitmap.Height - bottomShift))
            );

        Bitmap src = bitmap;
        Bitmap target = new Bitmap(cropRect.Width, cropRect.Height);

        using (Graphics g = Graphics.FromImage(target))
        {
            g.DrawImage(src, new Rectangle(0, 0, target.Width, target.Height), cropRect, GraphicsUnit.Pixel);

        }

        return target;
    }