C# Tutorial - Image Editing: Rotate

Good example. Clear source codes :)

Great example to get me started - could sort the clipping out though?

I am using this rotateImage to rotate an image during acquire event during scanning. However, the image is saved very very small and hugs the right side of the page. Any ideas?

This fades the whole image and if you keep rotating, the image gets messed up.

Any one noticed?

Thank you

Thank for your sample code :)

Thanks for the good sample code.

Your code has saved me. If I weren't a Christian, I would ask you to me my Savior.

This is most excellent. Thanks so much.

nice comment

Very helpful and nicely commented and explained :)

Good example with clear codes..Thanks to the author

God bless you man! ;-) thanks very much.

If you just need to rotate (and flip) by a multiple of 90 use

image.RotateFlip(RotateFlipType);

The graphics I get at the end are the wrong dimensions and the contents are pushed out to the side and mostly cut off.

Any suggestions?

hey help me to identify a circle in a image. it can be of any diameter.but i will have one of the pixel of that circle.

This code works well but there seem to be certain issues that i am facing.

1.one that a few people have mentioned about the rotated image being clipped as the bounding rectangle stays the same

?2. Rotating the image a lot, makes it blurry and unclear.

My approach would be to build a rotation matrix and apply the to the corners of the rectangle. Is there an easier way to do this.

Hello, could use some help plz //move image back g.TranslateTransform(-(float)b.Width/2,-(float)b.Height / 2);

i dont understand why cant I just write g.TranslateTransform(b.Width * 2, b.Height * 2);

thanks in advance

thanx bgt broo..makin cakep deh kamu..

/// <summary>
/// Rotates the input image by theta degrees around center.
/// </summary>
public static Bitmap rotateCenter(Bitmap bmpSrc, float theta)
{
  Matrix mRotate = new Matrix();
  mRotate.Translate(bmpSrc.Width / -2, bmpSrc.Height / -2, MatrixOrder.Append);
mRotate.RotateAt(theta, new Point(0, 0), MatrixOrder.Append);
            using (GraphicsPath gp = new GraphicsPath())
            {  // transform image points by rotation matrix
                gp.AddPolygon(new Point[] { new Point(0, 0), new Point(bmpSrc.Width, 0), new Point(0, bmpSrc.Height) });
                gp.Transform(mRotate);
                PointF[] pts = gp.PathPoints;

                // create destination bitmap sized to contain rotated source image
                Rectangle bbox = boundingBox(bmpSrc, mRotate);
                Bitmap bmpDest = new Bitmap(bbox.Width, bbox.Height);

                using (Graphics gDest = Graphics.FromImage(bmpDest))
                {  // draw source into dest
                    Matrix mDest = new Matrix();
                    mDest.Translate(bmpDest.Width / 2, bmpDest.Height / 2, MatrixOrder.Append);
                    gDest.Transform = mDest;
                    gDest.DrawImage(bmpSrc, pts);
                    gDest.DrawRectangle(Pens.Red, bbox);
                    //drawAxes(gDest, Color.Red, 0, 0, 1, 100, "");
                    return bmpDest;
                }
            }
        }

        private static Rectangle boundingBox(Image img, Matrix matrix)
        {
            GraphicsUnit gu = new GraphicsUnit();
            Rectangle rImg = Rectangle.Round(img.GetBounds(ref gu));

            // Transform the four points of the image, to get the resized bounding box.
            Point topLeft = new Point(rImg.Left, rImg.Top);
            Point topRight = new Point(rImg.Right, rImg.Top);
            Point bottomRight = new Point(rImg.Right, rImg.Bottom);
            Point bottomLeft = new Point(rImg.Left, rImg.Bottom);
            Point[] points = new Point[] { topLeft, topRight, bottomRight, bottomLeft };
            GraphicsPath gp = new GraphicsPath(points,
                                                                new byte[] { (byte)PathPointType.Start, (byte)PathPointType.Line, (byte)PathPointType.Line, (byte)PathPointType.Line });
            gp.Transform(matrix);
            return Rectangle.Round(gp.GetBounds());
        }

Im trying to rotate an image using this method but im using a back buffer and just want to rotate an image on it. When i try to use this it is rotating all my images. Can anyone help please.

very nice thanks

hey that really helped a lot.Thanks a lot...but how can this code be used for multiple images can u please tell...

hello i have 2 image i use surf descriptor to specify each picture i want for example i have two similar images, the second image is turned at x degrees in relation with first i would like to countdown the x degrees how can i do this with surf discriptor or can i use anything else ???

thanks

Hi, I adapted your code slightly to rotate a stretched/shrunk image within a C sharp pictureBox and to fix the ensuing bounding box issues.

Here is the new function:

private Bitmap rotateImage(Bitmap b, float angle) { Bitmap returnBitmap = new Bitmap(b.Width, b.Height + 1); Graphics g = Graphics.FromImage(returnBitmap); g.TranslateTransform((float)b.Width / 2, (float)b.Height / 2); g.RotateTransform(angle); g.TranslateTransform(-(float)b.Width / 2, -(float)b.Height / 2); g.DrawImage(b, b.Width / 2 - b.Height / 2, b.Height / 2 - b.Width / 2, b.Height, b.Width); return returnBitmap; }

And here's how I used that function to load an image locally, rotate it, and then stretch it to fit a pictureBox:

path = //path of filename goes here rotationAngle = //rotation angle you want goes here

pictureBox1.SizeMode = PictureBoxSizeMode.CenterImage; pictureBox1.ImageLocation = path; pictureBox1.Load(); _BackBuffer = new Bitmap(pictureBox1.Image); pictureBox1.Image = rotateImage(_BackBuffer, rotationAngle); pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;

Of course, by "for all other angles" I meant ones that are not 90, 180, or 270.

Hi, I want to draw a lot of rectangles with different angles in one graphic object. Is it possible?

I am having problems implementing the updates cropped corners method above because of the PointF. Can I please have an example of what the method call should be?

Hi there thank you so much your code has been very helpfull jst a question i'm not sure which classes i'm supposed to be using when i inserted your code it tells me that Matrix could not be found, So i must put using System.??? Thanks :)

Thanks to Anonymous for posting Rotates the input image by theta degrees around center.

I could not get this to work. I don't care about corner clipping because my images are round (have no corners). I have a second hand (clock) image where the hand points up (12 oclock). I want to rotate it by some positive or negative angle in degrees so I tried this, but the image also gets translated. Why?

Is it possible to make the space voided by rotating the image transparent?

hi, can anybody help me about plate recognition C# algorithm

please i want the source code of the images brightness

please

thank you

Hello, please I want a way to deal with the brightness images programmatically by using C# .. my darling please help me As soon as possible…. Best regards Thank You for Everything

I had some trouble as the resulting image would not be the right size and some clipping occured on the edges.

changing:

g.DrawImage(b, new Point(0, 0));

to:

g.DrawImage(b, new Rectangle(new Point(0,0), new Size(b.Width, b.Height)));

took care of it though.

Thanks for the function, good work!

Here's a more flexible version that supports rotation with and without clipping and any angle between -180 to +180 degrees.

public static Bitmap RotateImage(Image image, float rotateAtX, float rotateAtY, float angle, bool bNoClip)
{
    int W, H, X, Y;
    if (bNoClip)
    {
    double dW = (double)image.Width;
    double dH = (double)image.Height;

    double degrees = Math.Abs(angle);
    if (degrees <= 90)
    {
        double radians = 0.0174532925 * degrees;
        double dSin = Math.Sin(radians);
        double dCos = Math.Cos(radians);
        W = (int)(dH * dSin + dW * dCos);
        H = (int)(dW * dSin + dH * dCos);
        X = (W - image.Width) / 2;
        Y = (H - image.Height) / 2;
    }
    else
    {
        degrees -= 90;
        double radians = 0.0174532925 * degrees;
        double dSin = Math.Sin(radians);
        double dCos = Math.Cos(radians);
        W = (int)(dW * dSin + dH * dCos);
        H = (int)(dH * dSin + dW * dCos);
        X = (W - image.Width) / 2;
        Y = (H - image.Height) / 2;
    }
    }
    else
    {
    W = image.Width;
    H = image.Height;
    X = 0;
    Y = 0;
    }

    //create a new empty bitmap to hold rotated image
    Bitmap bmpRet = new Bitmap(W, H);
    bmpRet.SetResolution(image.HorizontalResolution, image.VerticalResolution);

    //make a graphics object from the empty bitmap
    Graphics g = Graphics.FromImage(bmpRet);

    //Put the rotation point in the "center" of the image
    g.TranslateTransform(rotateAtX+X, rotateAtY+Y);

    //rotate the image
    g.RotateTransform(angle);

    //move the image back
    g.TranslateTransform(-rotateAtX - X, -rotateAtY - Y);

    //draw passed in image onto graphics object
    g.DrawImage(image, new PointF(0+X, 0+Y));

    return bmpRet;
}

thank you brother God Bless You Jai SiyaRam

thanks....

Nice examples.... thank you,.

Thank You!!

my image is getting 1/3 smaller in bytes. does anyone know how to keep the image resolution after rotation?

var rotation = Math.PI * degrees / 180; var costheta = Math.Cos(rotation); var sintheta = Math.Sin(rotation); var newWidth = (float)(Math.Abs(costheta * b.Width) + Math.Abs(sintheta * b.Width)); var newHeight = (float)(Math.Abs(costheta * b.Height) + Math.Abs(sintheta * b.Height));

//Ceiling the height and width to the nearest even number if (b.Width % 2 == 0) newWidth = (Math.Ceiling(newWidth) % 2 == 1) ? (float)Math.Ceiling(newWidth + 1) : (float)Math.Ceiling(newWidth); if (b.Height % 2 == 0) newHeight = (Math.Ceiling(newHeight) % 2 == 1) ? (float)Math.Ceiling(newHeight + 1) : (float)Math.Ceiling(newHeight);

//offset var x = Math.Abs((newWidth - b.Width) / 2); var y = Math.Abs((newHeight - b.Height) / 2);

//create a new empty bitmap to hold rotated image Bitmap returnBitmap = new Bitmap((int)newWidth, (int)newHeight); returnBitmap.SetResolution(b.HorizontalResolution, b.VerticalResolution); //make a graphics object from the empty bitmap Graphics g = Graphics.FromImage(returnBitmap); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

var rotateXAt = newWidth / 2; var rotateYAt = newHeight / 2;

///move rotation point to center of image g.TranslateTransform(rotateXAt, rotateYAt); //rotate g.RotateTransform(degrees);

//move image back g.TranslateTransform(-rotateXAt, -rotateYAt);

//draw passed in image onto graphics object g.DrawImage(b, new PointF(x, y));

return returnBitmap;