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GDI Resize Image & Guarantee Height

I'm dynamically creating isometric tiles from standard top-down tiles from another game. The problem, though, is that the the image resize often ends up with some amount of pixels "missing" on either side. I understand they're not really missing and the code is working properly but I don't know enough about GDI to know what settings/tutorials to search for.
I take this: and turn it into this: .
It goes from 32x32 to 48x24, which is the correct proportion. However, on the left and bottom, the grass is one pixel short of reaching the edge of the image. I don't want to fix this manually as I'll be doing this for hundreds of tiles so I'd like to find a way to fix this in the code. The issue, in the end, is that the tiles end up with tiny one-pixel gaps between them.
Is there anything I can do with GDI other than just checking each image for the edge colors and adding them manually if they're missing/transparent?
Here's the code I used to do this. The commented out parts are some of the various settings I've been messing with:
Bitmap bmp = RotateImage(new Bitmap(fileName), 45);
bmp = ResizeImage(bmp, bmp.Width, bmp.Height / 2);
private static Bitmap RotateImage(Bitmap rotateMe, float angle)
{
//First, re-center the image in a larger image that has a margin/frame
//to compensate for the rotated image's increased size
var bmp = new Bitmap(rotateMe.Width + (rotateMe.Width / 2), rotateMe.Height + (rotateMe.Height / 2));
using (Graphics g = Graphics.FromImage(bmp))
g.DrawImageUnscaled(rotateMe, (rotateMe.Width / 4), (rotateMe.Height / 4), bmp.Width, bmp.Height);
rotateMe = bmp;
//Now, actually rotate the image
Bitmap rotatedImage = new Bitmap(rotateMe.Width, rotateMe.Height);
using (Graphics g = Graphics.FromImage(rotatedImage))
{
g.TranslateTransform(rotateMe.Width / 2, rotateMe.Height / 2); //set the rotation point as the center into the matrix
g.RotateTransform(angle); //rotate
g.TranslateTransform(-rotateMe.Width / 2, -rotateMe.Height / 2); //restore rotation point into the matrix
g.DrawImage(rotateMe, new Point(0, 0)); //draw the image on the new bitmap
}
return rotatedImage;
}
private static Bitmap ResizeImage(System.Drawing.Image image, int width, int height)
{
var destRect = new Rectangle(0, 0, width, height);
var destImage = new Bitmap(width, height);
destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);
using (var graphics = Graphics.FromImage(destImage))
{
//graphics.CompositingMode = CompositingMode.SourceCopy;
//graphics.CompositingQuality = CompositingQuality.HighQuality;
//graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
//graphics.SmoothingMode = SmoothingMode.HighQuality;
//graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphics.InterpolationMode = InterpolationMode.NearestNeighbor;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphics.SmoothingMode = SmoothingMode.AntiAlias;
using (var wrapMode = new ImageAttributes())
{
wrapMode.SetWrapMode(WrapMode.TileFlipXY);
graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);
}
}
return destImage;
}

You might want to consider calculating the Width and Height of your rotated object.
For example:
private void button1_Click(object sender, EventArgs e)
{
var width = (int) numericUpDown2.Value;
var height = (int) numericUpDown3.Value;
var angle = (float) numericUpDown1.Value;
var size = new Size(width, height);
var result = RotatedSettings(angle, size);
textBox1.Text = String.Format("{0} x {1}", result.Width, result.Height);
}
private static Size RotatedSettings(float angle, Size size)
{
// setup corner values in array
var corners = new[]
{ new PointF(0, 0),
new PointF(size.Width, 0),
new PointF(0, size.Height),
new PointF(size.Width, size.Height)};
// rotate corners
var xc = corners.Select(p => Rotate(p, (float)angle).X);
var yc = corners.Select(p => Rotate(p, (float)angle).Y);
// find the new sizes by subtracting highest from lowest result.
var widths = xc as IList<float> ?? xc.ToList();
var newWidth = (int)Math.Abs(widths.Max() - widths.Min());
var heights = yc as IList<float> ?? yc.ToList();
var newHeight = (int)Math.Abs(heights.Max() - heights.Min());
// as we rotate the mid point we need to middle midpoint section and add the outcome to size.
var midX = ((size.Width / 2) - ((double)newWidth / 2));
var midY = ((size.Height / 2) - ((double)newHeight / 2));
return new Size(newWidth + (int)midX, newHeight + (int)midY);
}
/// <summary>
/// Rotates a point around the origin (0,0)
/// </summary>
private static PointF Rotate(PointF p, float angle)
{
// convert from angle to radians
var theta = Math.PI * angle / 180;
return new PointF(
(float)(Math.Cos(theta) * (p.X) - Math.Sin(theta) * (p.Y)),
(float)(Math.Sin(theta) * (p.X) + Math.Cos(theta) * (p.Y)));
}

Get resulting size of RotateTransform

I've got the following code for rotating an image in C#:
private Bitmap RotateImage(Bitmap b, float angle)
{
//create a new empty bitmap to hold rotated image
Bitmap returnBitmap = new Bitmap(b.Width, b.Height);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(returnBitmap);
//move rotation point to center of image
g.TranslateTransform((float)returnBitmap.Width / 2, (float)returnBitmap.Height / 2);
//rotate
g.RotateTransform(angle);
//move image back
g.TranslateTransform(-(float)b.Width / 2, -(float)b.Height / 2);
//draw passed in image onto graphics object
g.DrawImage(b, new Rectangle(new Point(0, 0), new Size(b.Width, b.Height)));
return returnBitmap;
}
It works very well, except that it clips the result when it exceeds original bounds.
As I understood, I have to set returnBitmap's size to the size of image after rotation. But how do I find how big the result will be, to set size of the new bitmap accordingly?

You need to rotate the four corners of your original image and calculate the bounding box for the new coordinates:
private static Bitmap RotateImage(Image b, float angle)
{
var corners = new[]
{new PointF(0, 0), new Point(b.Width, 0), new PointF(0, b.Height), new PointF(b.Width, b.Height)};
var xc = corners.Select(p => Rotate(p, angle).X);
var yc = corners.Select(p => Rotate(p, angle).Y);
//create a new empty bitmap to hold rotated image
Bitmap returnBitmap = new Bitmap((int)Math.Abs(xc.Max() - xc.Min()), (int)Math.Abs(yc.Max() - yc.Min()));
...
}
/// <summary>
/// Rotates a point around the origin (0,0)
/// </summary>
private static PointF Rotate(PointF p, float angle)
{
// convert from angle to radians
var theta = Math.PI*angle/180;
return new PointF(
(float) (Math.Cos(theta)*(p.X) - Math.Sin(theta)*(p.Y)),
(float) (Math.Sin(theta)*(p.X) + Math.Cos(theta)*(p.Y)));
}

Pythagoras. It is anywhere from original to sqrt(w^2 + h^2) at 90/270 angle. And I d bet it is determined by sine (max at 90).

How to rotate picturebox

I need to solve a problem by rotating an image, but I have this code to rotate the image does not rotate completely
public static Image RotateImage(Image img, float rotationAngle)
{
//create an empty Bitmap image
Bitmap bmp = new Bitmap(img.Width, img.Height);
//turn the Bitmap into a Graphics object
Graphics gfx = Graphics.FromImage(bmp);
//now we set the rotation point to the center of our image
gfx.TranslateTransform((float)bmp.Width / 2, (float)bmp.Height / 2);
//now rotate the image
gfx.RotateTransform(rotationAngle);
gfx.TranslateTransform(-(float)bmp.Width / 2, -(float)bmp.Height / 2);
//set the InterpolationMode to HighQualityBicubic so to ensure a high
//quality image once it is transformed to the specified size
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
//now draw our new image onto the graphics object
gfx.DrawImage(img, new System.Drawing.Point(0, 0));
//dispose of our Graphics object
gfx.Dispose();
//return the image
return bmp;
}
And use this to call method. The right is rotate the image rectangle that contains, and to avoid cutting the image
Bitmap bitmap = (Bitmap)Pix.Image;
Pix.Image = (Bitmap)(RotateImage(bitmap, 20.0f));

private Bitmap RotateImageByAngle(Image oldBitmap, float angle)
{
var newBitmap = new Bitmap(oldBitmap.Width, oldBitmap.Height);
newBitmap.SetResolution(oldBitmap.HorizontalResolution, oldBitmap.VerticalResolution);
var graphics = Graphics.FromImage(newBitmap);
graphics.TranslateTransform((float)oldBitmap.Width / 2, (float)oldBitmap.Height / 2);
graphics.RotateTransform(angle);
graphics.TranslateTransform(-(float)oldBitmap.Width / 2, -(float)oldBitmap.Height / 2);
graphics.DrawImage(oldBitmap, new Point(0, 0));
return newBitmap;
}

I have used in the past the following code from this article.
http://www.switchonthecode.com/tutorials/csharp-tutorial-image-editing-rotate
Has some other solutions as well.
/// <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);
//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());
}

How do I rotate a picture in WinForms

I want to have one picture in my application that I can rotate to indicate directions, like wind direction. Or even the time. What code do I use to rotate the picture? Thanks
Update: I am using .NET 2.0, Windows 2000, VS C# 2005

Here's a method you can use to rotate an image in C#:
/// <summary>
/// method to rotate an image either clockwise or counter-clockwise
/// </summary>
/// <param name="img">the image to be rotated</param>
/// <param name="rotationAngle">the angle (in degrees).
/// NOTE:
/// Positive values will rotate clockwise
/// negative values will rotate counter-clockwise
/// </param>
/// <returns></returns>
public static Image RotateImage(Image img, float rotationAngle)
{
//create an empty Bitmap image
Bitmap bmp = new Bitmap(img.Width, img.Height);
//turn the Bitmap into a Graphics object
Graphics gfx = Graphics.FromImage(bmp);
//now we set the rotation point to the center of our image
gfx.TranslateTransform((float)bmp.Width / 2, (float)bmp.Height / 2);
//now rotate the image
gfx.RotateTransform(rotationAngle);
gfx.TranslateTransform(-(float)bmp.Width / 2, -(float)bmp.Height / 2);
//set the InterpolationMode to HighQualityBicubic so to ensure a high
//quality image once it is transformed to the specified size
gfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
//now draw our new image onto the graphics object
gfx.DrawImage(img, new Point(0, 0));
//dispose of our Graphics object
gfx.Dispose();
//return the image
return bmp;
}

This is an old thread, and there are several other threads about C# WinForms image rotation, but now that I've come up with my solution I figure this is as good a place to post it as any.
/// <summary>
/// Method to rotate an Image object. The result can be one of three cases:
/// - upsizeOk = true: output image will be larger than the input, and no clipping occurs
/// - upsizeOk = false & clipOk = true: output same size as input, clipping occurs
/// - upsizeOk = false & clipOk = false: output same size as input, image reduced, no clipping
///
/// A background color must be specified, and this color will fill the edges that are not
/// occupied by the rotated image. If color = transparent the output image will be 32-bit,
/// otherwise the output image will be 24-bit.
///
/// Note that this method always returns a new Bitmap object, even if rotation is zero - in
/// which case the returned object is a clone of the input object.
/// </summary>
/// <param name="inputImage">input Image object, is not modified</param>
/// <param name="angleDegrees">angle of rotation, in degrees</param>
/// <param name="upsizeOk">see comments above</param>
/// <param name="clipOk">see comments above, not used if upsizeOk = true</param>
/// <param name="backgroundColor">color to fill exposed parts of the background</param>
/// <returns>new Bitmap object, may be larger than input image</returns>
public static Bitmap RotateImage(Image inputImage, float angleDegrees, bool upsizeOk,
bool clipOk, Color backgroundColor)
{
// Test for zero rotation and return a clone of the input image
if (angleDegrees == 0f)
return (Bitmap)inputImage.Clone();
// Set up old and new image dimensions, assuming upsizing not wanted and clipping OK
int oldWidth = inputImage.Width;
int oldHeight = inputImage.Height;
int newWidth = oldWidth;
int newHeight = oldHeight;
float scaleFactor = 1f;
// If upsizing wanted or clipping not OK calculate the size of the resulting bitmap
if (upsizeOk || !clipOk)
{
double angleRadians = angleDegrees * Math.PI / 180d;
double cos = Math.Abs(Math.Cos(angleRadians));
double sin = Math.Abs(Math.Sin(angleRadians));
newWidth = (int)Math.Round(oldWidth * cos + oldHeight * sin);
newHeight = (int)Math.Round(oldWidth * sin + oldHeight * cos);
}
// If upsizing not wanted and clipping not OK need a scaling factor
if (!upsizeOk && !clipOk)
{
scaleFactor = Math.Min((float)oldWidth / newWidth, (float)oldHeight / newHeight);
newWidth = oldWidth;
newHeight = oldHeight;
}
// Create the new bitmap object. If background color is transparent it must be 32-bit,
// otherwise 24-bit is good enough.
Bitmap newBitmap = new Bitmap(newWidth, newHeight, backgroundColor == Color.Transparent ?
PixelFormat.Format32bppArgb : PixelFormat.Format24bppRgb);
newBitmap.SetResolution(inputImage.HorizontalResolution, inputImage.VerticalResolution);
// Create the Graphics object that does the work
using (Graphics graphicsObject = Graphics.FromImage(newBitmap))
{
graphicsObject.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphicsObject.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphicsObject.SmoothingMode = SmoothingMode.HighQuality;
// Fill in the specified background color if necessary
if (backgroundColor != Color.Transparent)
graphicsObject.Clear(backgroundColor);
// Set up the built-in transformation matrix to do the rotation and maybe scaling
graphicsObject.TranslateTransform(newWidth / 2f, newHeight / 2f);
if (scaleFactor != 1f)
graphicsObject.ScaleTransform(scaleFactor, scaleFactor);
graphicsObject.RotateTransform(angleDegrees);
graphicsObject.TranslateTransform(-oldWidth / 2f, -oldHeight / 2f);
// Draw the result
graphicsObject.DrawImage(inputImage, 0, 0);
}
return newBitmap;
}
This is the result of many sources of inspiration, here at StackOverflow and elsewhere. Naveen's answer on this thread was especially helpful.

Simple method:
public Image RotateImage(Image img)
{
var bmp = new Bitmap(img);
using (Graphics gfx = Graphics.FromImage(bmp))
{
gfx.Clear(Color.White);
gfx.DrawImage(img, 0, 0, img.Width, img.Height);
}
bmp.RotateFlip(RotateFlipType.Rotate270FlipNone);
return bmp;
}

I found this article
/// <summary>
/// Creates a new Image containing the same image only rotated
/// </summary>
/// <param name=""image"">The <see cref=""System.Drawing.Image"/"> to rotate
/// <param name=""offset"">The position to rotate from.
/// <param name=""angle"">The amount to rotate the image, clockwise, in degrees
/// <returns>A new <see cref=""System.Drawing.Bitmap"/"> of the same size rotated.</see>
/// <exception cref=""System.ArgumentNullException"">Thrown if <see cref=""image"/">
/// is null.</see>
public static Bitmap RotateImage(Image image, PointF offset, float angle)
{
if (image == null)
throw new ArgumentNullException("image");
//create a new empty bitmap to hold rotated image
Bitmap rotatedBmp = new Bitmap(image.Width, image.Height);
rotatedBmp.SetResolution(image.HorizontalResolution, image.VerticalResolution);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(rotatedBmp);
//Put the rotation point in the center of the image
g.TranslateTransform(offset.X, offset.Y);
//rotate the image
g.RotateTransform(angle);
//move the image back
g.TranslateTransform(-offset.X, -offset.Y);
//draw passed in image onto graphics object
g.DrawImage(image, new PointF(0, 0));
return rotatedBmp;
}

I've written a simple class for rotating image. All you've to do is input image and angle of rotation in Degree. Angle must be between -90 and +90.
public class ImageRotator
{
private readonly Bitmap image;
public Image OriginalImage
{
get { return image; }
}
private ImageRotator(Bitmap image)
{
this.image = image;
}
private double GetRadian(double degree)
{
return degree * Math.PI / (double)180;
}
private Size CalculateSize(double angle)
{
double radAngle = GetRadian(angle);
int width = (int)(image.Width * Math.Cos(radAngle) + image.Height * Math.Sin(radAngle));
int height = (int)(image.Height * Math.Cos(radAngle) + image.Width * Math.Sin(radAngle));
return new Size(width, height);
}
private PointF GetTopCoordinate(double radAngle)
{
Bitmap image = CurrentlyViewedMappedImage.BitmapImage;
double topX = 0;
double topY = 0;
if (radAngle > 0)
{
topX = image.Height * Math.Sin(radAngle);
}
if (radAngle < 0)
{
topY = image.Width * Math.Sin(-radAngle);
}
return new PointF((float)topX, (float)topY);
}
public Bitmap RotateImage(double angle)
{
SizeF size = CalculateSize(radAngle);
Bitmap rotatedBmp = new Bitmap((int)size.Width, (int)size.Height);
Graphics g = Graphics.FromImage(rotatedBmp);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.TranslateTransform(topPoint.X, topPoint.Y);
g.RotateTransform(GetDegree(radAngle));
g.DrawImage(image, new RectangleF(0, 0, size.Width, size.Height));
g.Dispose();
return rotatedBmp;
}
public static class Builder
{
public static ImageRotator CreateInstance(Image image)
{
ImageRotator rotator = new ImageRotator(image as Bitmap);
return rotator;
}
}
}

Old question but I had to address MrFox's comment in the accepted answer. Rotating an image when the size changes cuts off the edges of the image. One solution is to redraw the original on a larger image, centered, where the larger image's dimensions compensate for the need of not clipping the edges. For example, I wanted to be able to design a game's tiles at a normal angle but re-draw them at a 45-degree angle for an isometric view.
Here are example images (yellow borders are to make it easier to see here).
The original image:
The centered tile in a larger image:
The rotated image (where you rotate the larger image, not the original):
The code (based in part on this answer in another question):
private Bitmap RotateImage(Bitmap rotateMe, float angle)
{
//First, re-center the image in a larger image that has a margin/frame
//to compensate for the rotated image's increased size
var bmp = new Bitmap(rotateMe.Width + (rotateMe.Width / 2), rotateMe.Height + (rotateMe.Height / 2));
using (Graphics g = Graphics.FromImage(bmp))
g.DrawImageUnscaled(rotateMe, (rotateMe.Width / 4), (rotateMe.Height / 4), bmp.Width, bmp.Height);
bmp.Save("moved.png");
rotateMe = bmp;
//Now, actually rotate the image
Bitmap rotatedImage = new Bitmap(rotateMe.Width, rotateMe.Height);
using (Graphics g = Graphics.FromImage(rotatedImage))
{
g.TranslateTransform(rotateMe.Width / 2, rotateMe.Height / 2); //set the rotation point as the center into the matrix
g.RotateTransform(angle); //rotate
g.TranslateTransform(-rotateMe.Width / 2, -rotateMe.Height / 2); //restore rotation point into the matrix
g.DrawImage(rotateMe, new Point(0, 0)); //draw the image on the new bitmap
}
rotatedImage.Save("rotated.png");
return rotatedImage;
}

Richard Cox has a good solution to this https://stackoverflow.com/a/5200280/1171321 I have used in the past. It is also worth noting the DPI must be 96 for this to work correctly. Several of the solutions on this page do not work at all.

Rotating image is one thing, proper image boundaries in another. Here is a code which can help anyone. I created this based on some search on internet long ago.
/// <summary>
/// Rotates image in radian angle
/// </summary>
/// <param name="bmpSrc"></param>
/// <param name="theta">in radian</param>
/// <param name="extendedBitmapBackground">Because of rotation returned bitmap can have different boundaries from original bitmap. This color is used for filling extra space in bitmap</param>
/// <returns></returns>
public static Bitmap RotateImage(Bitmap bmpSrc, double theta, Color? extendedBitmapBackground = null)
{
theta = Convert.ToSingle(theta * 180 / Math.PI);
Matrix mRotate = new Matrix();
mRotate.Translate(bmpSrc.Width / -2, bmpSrc.Height / -2, MatrixOrder.Append);
mRotate.RotateAt((float)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))
{
if (extendedBitmapBackground != null)
{
gDest.Clear(extendedBitmapBackground.Value);
}
// 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);
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());
}

This will work as long as the image you want to rotate is already in your Properties resources folder.
In Partial Class:
Bitmap bmp2;
OnLoad:
bmp2 = new Bitmap(Tycoon.Properties.Resources.save2);
pictureBox6.SizeMode = PictureBoxSizeMode.StretchImage;
pictureBox6.Image = bmp2;
Button or Onclick
private void pictureBox6_Click(object sender, EventArgs e)
{
if (bmp2 != null)
{
bmp2.RotateFlip(RotateFlipType.Rotate90FlipNone);
pictureBox6.Image = bmp2;
}
}

You can easily do it by calling this method :
public static Bitmap RotateImage(Image image, float angle)
{
if (image == null)
throw new ArgumentNullException("image");
PointF offset = new PointF((float)image.Width / 2, (float)image.Height / 2);
//create a new empty bitmap to hold rotated image
Bitmap rotatedBmp = new Bitmap(image.Width, image.Height);
rotatedBmp.SetResolution(image.HorizontalResolution, image.VerticalResolution);
//make a graphics object from the empty bitmap
Graphics g = Graphics.FromImage(rotatedBmp);
//Put the rotation point in the center of the image
g.TranslateTransform(offset.X, offset.Y);
//rotate the image
g.RotateTransform(angle);
//move the image back
g.TranslateTransform(-offset.X, -offset.Y);
//draw passed in image onto graphics object
g.DrawImage(image, new PointF(0, 0));
return rotatedBmp;
}
don't forget to add a reference to System.Drawing.dll on your project
Example of this method call :
Image image = new Bitmap("waves.png");
Image newImage = RotateImage(image, 360);
newImage.Save("newWaves.png");

I have modified the function of Mr.net_prog which gets only the picture box and rotate the image in it.
public static void RotateImage(PictureBox picBox)
{
Image img = picBox.Image;
var bmp = new Bitmap(img);
using (Graphics gfx = Graphics.FromImage(bmp))
{
gfx.Clear(Color.White);
gfx.DrawImage(img, 0, 0, img.Width, img.Height);
}
bmp.RotateFlip(RotateFlipType.Rotate270FlipNone);
picBox.Image = bmp;
}

This solution assumes that you want to draw the image in a picture box and that the image orientation will follow the mouse movements over this picture box. No image is assigned to the picture box. Instead I'm getting the image from a project resource.
private float _angle;
public Form1()
{
InitializeComponent();
}
private void PictureBox_MouseMove(object sender, MouseEventArgs e)
{
(float centerX, float centerY) = GetCenter(pictureBox1.ClientRectangle);
_angle = (float)(Math.Atan2(e.Y - centerY, e.X - centerX) * 180.0 / Math.PI);
pictureBox1.Invalidate(); // Triggers redrawing
}
private void PictureBox_Paint(object sender, PaintEventArgs e)
{
Bitmap image = Properties.Resources.ExampleImage;
float scale = (float)pictureBox1.Width / image.Width;
(float centerX, float centerY) = GetCenter(e.ClipRectangle);
e.Graphics.TranslateTransform(centerX, centerY);
e.Graphics.RotateTransform(_angle);
e.Graphics.TranslateTransform(-centerX, -centerY);
e.Graphics.ScaleTransform(scale, scale);
e.Graphics.DrawImage(image, 0, 0);
}
// Uses C# 7.0 value tuples / .NET Framework 4.7.
// For previous versions, return a PointF instead.
private static (float, float) GetCenter(Rectangle rect)
{
float centerX = (rect.Left + rect.Right) * 0.5f;
float centerY = (rect.Top + rect.Bottom) * 0.5f;
return (centerX, centerY);
}
Make sure to to select the mouse event handlers PictureBox_MouseMove and PictureBox_Paint in properties window of the picture box for these events, after you copy/pasted this code into the form.
Note: You could also use a simple Panel or any other control, like a label; however, the PictureBox has the advantage to use double buffering by default, which eliminates flickering.

How to resize an Image C#

As Size, Width and Height are Get() properties of System.Drawing.Image;
How can I resize an Image object at run-time in C#?
Right now, I am just creating a new Image using:
// objImage is the original Image
Bitmap objBitmap = new Bitmap(objImage, new Size(227, 171));

This will perform a high quality resize:
/// <summary>
/// Resize the image to the specified width and height.
/// </summary>
/// <param name="image">The image to resize.</param>
/// <param name="width">The width to resize to.</param>
/// <param name="height">The height to resize to.</param>
/// <returns>The resized image.</returns>
public static Bitmap ResizeImage(Image image, int width, int height)
{
var destRect = new Rectangle(0, 0, width, height);
var destImage = new Bitmap(width, height);
destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);
using (var graphics = Graphics.FromImage(destImage))
{
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.SmoothingMode = SmoothingMode.HighQuality;
graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
using (var wrapMode = new ImageAttributes())
{
wrapMode.SetWrapMode(WrapMode.TileFlipXY);
graphics.DrawImage(image, destRect, 0, 0, image.Width,image.Height, GraphicsUnit.Pixel, wrapMode);
}
}
return destImage;
}
wrapMode.SetWrapMode(WrapMode.TileFlipXY) prevents ghosting around the image borders -- naïve resizing will sample transparent pixels beyond the image boundaries, but by mirroring the image we can get a better sample (this setting is very noticeable)
destImage.SetResolution maintains DPI regardless of physical size -- may increase quality when reducing image dimensions or when printing
Compositing controls how pixels are blended with the background -- might not be needed since we're only drawing one thing.
graphics.CompositingMode determines whether pixels from a source image overwrite or are combined with background pixels. SourceCopy specifies that when a color is rendered, it overwrites the background color.
graphics.CompositingQuality determines the rendering quality level of layered images.
graphics.InterpolationMode determines how intermediate values between two endpoints are calculated
graphics.SmoothingMode specifies whether lines, curves, and the edges of filled areas use smoothing (also called antialiasing) -- probably only works on vectors
graphics.PixelOffsetMode affects rendering quality when drawing the new image
Maintaining aspect ratio is left as an exercise for the reader (actually, I just don't think it's this function's job to do that for you).
Also, this is a good article describing some of the pitfalls with image resizing. The above function will cover most of them, but you still have to worry about saving.

Not sure what is so difficult about this, do what you were doing, use the overloaded Bitmap constructor to create a re-sized image, the only thing you were missing was a cast back to the Image data type:
public static Image resizeImage(Image imgToResize, Size size)
{
return (Image)(new Bitmap(imgToResize, size));
}
yourImage = resizeImage(yourImage, new Size(50,50));

in this question, you'll have some answers, including mine:
public Image resizeImage(int newWidth, int newHeight, string stPhotoPath)
{
Image imgPhoto = Image.FromFile(stPhotoPath);
int sourceWidth = imgPhoto.Width;
int sourceHeight = imgPhoto.Height;
//Consider vertical pics
if (sourceWidth < sourceHeight)
{
int buff = newWidth;
newWidth = newHeight;
newHeight = buff;
}
int sourceX = 0, sourceY = 0, destX = 0, destY = 0;
float nPercent = 0, nPercentW = 0, nPercentH = 0;
nPercentW = ((float)newWidth / (float)sourceWidth);
nPercentH = ((float)newHeight / (float)sourceHeight);
if (nPercentH < nPercentW)
{
nPercent = nPercentH;
destX = System.Convert.ToInt16((newWidth -
(sourceWidth * nPercent)) / 2);
}
else
{
nPercent = nPercentW;
destY = System.Convert.ToInt16((newHeight -
(sourceHeight * nPercent)) / 2);
}
int destWidth = (int)(sourceWidth * nPercent);
int destHeight = (int)(sourceHeight * nPercent);
Bitmap bmPhoto = new Bitmap(newWidth, newHeight,
PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(imgPhoto.HorizontalResolution,
imgPhoto.VerticalResolution);
Graphics grPhoto = Graphics.FromImage(bmPhoto);
grPhoto.Clear(Color.Black);
grPhoto.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
grPhoto.DrawImage(imgPhoto,
new Rectangle(destX, destY, destWidth, destHeight),
new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight),
GraphicsUnit.Pixel);
grPhoto.Dispose();
imgPhoto.Dispose();
return bmPhoto;
}

You could try net-vips, the C# binding for libvips. It's a lazy, streaming, demand-driven image processing library, so it can do operations like this without needing to load the whole image.
For example, it comes with a handy image thumbnailer:
using Image image = Image.Thumbnail("image.jpg", 300, 300);
image.WriteToFile("my-thumbnail.jpg");
It also supports smart crop, a way of intelligently determining the most important part of the image and keeping it in focus while cropping the image. For example:
using Image image = Image.Thumbnail("owl.jpg", 128, crop: Enums.Interesting.Attention);
image.WriteToFile("tn_owl.jpg");
Where owl.jpg is an off-centre composition:
Gives this result:
First it shrinks the image to get the vertical axis to 128 pixels, then crops down to 128 pixels across using the attention strategy. This one searches the image for features which might catch a human eye, see Smartcrop() for details.

Why not use the System.Drawing.Image.GetThumbnailImage method?
public Image GetThumbnailImage(
int thumbWidth,
int thumbHeight,
Image.GetThumbnailImageAbort callback,
IntPtr callbackData)
Example:
Image originalImage = System.Drawing.Image.FromStream(inputStream, true, true);
Image resizedImage = originalImage.GetThumbnailImage(newWidth, (newWidth * originalImage.Height) / originalWidth, null, IntPtr.Zero);
resizedImage.Save(imagePath, ImageFormat.Png);
Source:
http://msdn.microsoft.com/en-us/library/system.drawing.image.getthumbnailimage.aspx

public static Image resizeImage(Image image, int new_height, int new_width)
{
Bitmap new_image = new Bitmap(new_width, new_height);
Graphics g = Graphics.FromImage((Image)new_image );
g.InterpolationMode = InterpolationMode.High;
g.DrawImage(image, 0, 0, new_width, new_height);
return new_image;
}

This will -
Resize width AND height without the need for a loop
Doesn't exceed the images original dimensions
//////////////
private void ResizeImage(Image img, double maxWidth, double maxHeight)
{
double resizeWidth = img.Source.Width;
double resizeHeight = img.Source.Height;
double aspect = resizeWidth / resizeHeight;
if (resizeWidth > maxWidth)
{
resizeWidth = maxWidth;
resizeHeight = resizeWidth / aspect;
}
if (resizeHeight > maxHeight)
{
aspect = resizeWidth / resizeHeight;
resizeHeight = maxHeight;
resizeWidth = resizeHeight * aspect;
}
img.Width = resizeWidth;
img.Height = resizeHeight;
}

This code is same as posted from one of above answers.. but will convert transparent pixel to white instead of black ... Thanks:)
public Image resizeImage(int newWidth, int newHeight, string stPhotoPath)
{
Image imgPhoto = Image.FromFile(stPhotoPath);
int sourceWidth = imgPhoto.Width;
int sourceHeight = imgPhoto.Height;
//Consider vertical pics
if (sourceWidth < sourceHeight)
{
int buff = newWidth;
newWidth = newHeight;
newHeight = buff;
}
int sourceX = 0, sourceY = 0, destX = 0, destY = 0;
float nPercent = 0, nPercentW = 0, nPercentH = 0;
nPercentW = ((float)newWidth / (float)sourceWidth);
nPercentH = ((float)newHeight / (float)sourceHeight);
if (nPercentH < nPercentW)
{
nPercent = nPercentH;
destX = System.Convert.ToInt16((newWidth -
(sourceWidth * nPercent)) / 2);
}
else
{
nPercent = nPercentW;
destY = System.Convert.ToInt16((newHeight -
(sourceHeight * nPercent)) / 2);
}
int destWidth = (int)(sourceWidth * nPercent);
int destHeight = (int)(sourceHeight * nPercent);
Bitmap bmPhoto = new Bitmap(newWidth, newHeight,
PixelFormat.Format24bppRgb);
bmPhoto.SetResolution(imgPhoto.HorizontalResolution,
imgPhoto.VerticalResolution);
Graphics grPhoto = Graphics.FromImage(bmPhoto);
grPhoto.Clear(Color.White);
grPhoto.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
grPhoto.DrawImage(imgPhoto,
new Rectangle(destX, destY, destWidth, destHeight),
new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight),
GraphicsUnit.Pixel);
grPhoto.Dispose();
imgPhoto.Dispose();
return bmPhoto;
}

This is the code that I worked out for a specific requirement ie: the destination is always in landscape ratio. It should give you a good start.
public Image ResizeImage(Image source, RectangleF destinationBounds)
{
RectangleF sourceBounds = new RectangleF(0.0f,0.0f,(float)source.Width, (float)source.Height);
RectangleF scaleBounds = new RectangleF();
Image destinationImage = new Bitmap((int)destinationBounds.Width, (int)destinationBounds.Height);
Graphics graph = Graphics.FromImage(destinationImage);
graph.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
// Fill with background color
graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), destinationBounds);
float resizeRatio, sourceRatio;
float scaleWidth, scaleHeight;
sourceRatio = (float)source.Width / (float)source.Height;
if (sourceRatio >= 1.0f)
{
//landscape
resizeRatio = destinationBounds.Width / sourceBounds.Width;
scaleWidth = destinationBounds.Width;
scaleHeight = sourceBounds.Height * resizeRatio;
float trimValue = destinationBounds.Height - scaleHeight;
graph.DrawImage(source, 0, (trimValue / 2), destinationBounds.Width, scaleHeight);
}
else
{
//portrait
resizeRatio = destinationBounds.Height/sourceBounds.Height;
scaleWidth = sourceBounds.Width * resizeRatio;
scaleHeight = destinationBounds.Height;
float trimValue = destinationBounds.Width - scaleWidth;
graph.DrawImage(source, (trimValue / 2), 0, scaleWidth, destinationBounds.Height);
}
return destinationImage;
}

In the application I made it was necessary to create a function with multiple options. It's quite large, but it resizes the image, can keep the aspect ratio and can cut of the edges to return only the center of the image:
/// <summary>
/// Resize image with a directory as source
/// </summary>
/// <param name="OriginalFileLocation">Image location</param>
/// <param name="heigth">new height</param>
/// <param name="width">new width</param>
/// <param name="keepAspectRatio">keep the aspect ratio</param>
/// <param name="getCenter">return the center bit of the image</param>
/// <returns>image with new dimentions</returns>
public Image resizeImageFromFile(String OriginalFileLocation, int heigth, int width, Boolean keepAspectRatio, Boolean getCenter)
{
int newheigth = heigth;
System.Drawing.Image FullsizeImage = System.Drawing.Image.FromFile(OriginalFileLocation);
// Prevent using images internal thumbnail
FullsizeImage.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone);
FullsizeImage.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone);
if (keepAspectRatio || getCenter)
{
int bmpY = 0;
double resize = (double)FullsizeImage.Width / (double)width;//get the resize vector
if (getCenter)
{
bmpY = (int)((FullsizeImage.Height - (heigth * resize)) / 2);// gives the Y value of the part that will be cut off, to show only the part in the center
Rectangle section = new Rectangle(new Point(0, bmpY), new Size(FullsizeImage.Width, (int)(heigth * resize)));// create the section to cut of the original image
//System.Console.WriteLine("the section that will be cut off: " + section.Size.ToString() + " the Y value is minimized by: " + bmpY);
Bitmap orImg = new Bitmap((Bitmap)FullsizeImage);//for the correct effect convert image to bitmap.
FullsizeImage.Dispose();//clear the original image
using (Bitmap tempImg = new Bitmap(section.Width, section.Height))
{
Graphics cutImg = Graphics.FromImage(tempImg);// set the file to save the new image to.
cutImg.DrawImage(orImg, 0, 0, section, GraphicsUnit.Pixel);// cut the image and save it to tempImg
FullsizeImage = tempImg;//save the tempImg as FullsizeImage for resizing later
orImg.Dispose();
cutImg.Dispose();
return FullsizeImage.GetThumbnailImage(width, heigth, null, IntPtr.Zero);
}
}
else newheigth = (int)(FullsizeImage.Height / resize);// set the new heigth of the current image
}//return the image resized to the given heigth and width
return FullsizeImage.GetThumbnailImage(width, newheigth, null, IntPtr.Zero);
}
To make it easier to acces the function it's possible to add some overloaded functions:
/// <summary>
/// Resize image with a directory as source
/// </summary>
/// <param name="OriginalFileLocation">Image location</param>
/// <param name="heigth">new height</param>
/// <param name="width">new width</param>
/// <returns>image with new dimentions</returns>
public Image resizeImageFromFile(String OriginalFileLocation, int heigth, int width)
{
return resizeImageFromFile(OriginalFileLocation, heigth, width, false, false);
}
/// <summary>
/// Resize image with a directory as source
/// </summary>
/// <param name="OriginalFileLocation">Image location</param>
/// <param name="heigth">new height</param>
/// <param name="width">new width</param>
/// <param name="keepAspectRatio">keep the aspect ratio</param>
/// <returns>image with new dimentions</returns>
public Image resizeImageFromFile(String OriginalFileLocation, int heigth, int width, Boolean keepAspectRatio)
{
return resizeImageFromFile(OriginalFileLocation, heigth, width, keepAspectRatio, false);
}
Now are the last two booleans optional to set.
Call the function like this:
System.Drawing.Image ResizedImage = resizeImageFromFile(imageLocation, 800, 400, true, true);

public string CreateThumbnail(int maxWidth, int maxHeight, string path)
{
var image = System.Drawing.Image.FromFile(path);
var ratioX = (double)maxWidth / image.Width;
var ratioY = (double)maxHeight / image.Height;
var ratio = Math.Min(ratioX, ratioY);
var newWidth = (int)(image.Width * ratio);
var newHeight = (int)(image.Height * ratio);
var newImage = new Bitmap(newWidth, newHeight);
Graphics thumbGraph = Graphics.FromImage(newImage);
thumbGraph.CompositingQuality = CompositingQuality.HighQuality;
thumbGraph.SmoothingMode = SmoothingMode.HighQuality;
//thumbGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
thumbGraph.DrawImage(image, 0, 0, newWidth, newHeight);
image.Dispose();
string fileRelativePath = "newsizeimages/" + maxWidth + Path.GetFileName(path);
newImage.Save(Server.MapPath(fileRelativePath), newImage.RawFormat);
return fileRelativePath;
}
Click here http://bhupendrasinghsaini.blogspot.in/2014/07/resize-image-in-c.html

If you're working with a BitmapSource:
var resizedBitmap = new TransformedBitmap(
bitmapSource,
new ScaleTransform(scaleX, scaleY));
If you want finer control over quality, run this first:
RenderOptions.SetBitmapScalingMode(
bitmapSource,
BitmapScalingMode.HighQuality);
(Default is BitmapScalingMode.Linear which is equivalent to BitmapScalingMode.LowQuality.)

Note: this will not work with ASP.Net Core because WebImage depends on System.Web, but on previous versions of ASP.Net I used this snippet many times and was useful.
String ThumbfullPath = Path.GetFileNameWithoutExtension(file.FileName) + "80x80.jpg";
var ThumbfullPath2 = Path.Combine(ThumbfullPath, fileThumb);
using (MemoryStream stream = new MemoryStream(System.IO.File.ReadAllBytes(fullPath)))
{
var thumbnail = new WebImage(stream).Resize(80, 80);
thumbnail.Save(ThumbfullPath2, "jpg");
}

Use below function with below example for changing image size :
//Example :
System.Net.Mime.MediaTypeNames.Image newImage = System.Net.Mime.MediaTypeNames.Image.FromFile("SampImag.jpg");
System.Net.Mime.MediaTypeNames.Image temImag = FormatImage(newImage, 100, 100);
//image size modification unction
public static System.Net.Mime.MediaTypeNames.Image FormatImage(System.Net.Mime.MediaTypeNames.Image img, int outputWidth, int outputHeight)
{
Bitmap outputImage = null;
Graphics graphics = null;
try
{
outputImage = new Bitmap(outputWidth, outputHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
graphics = Graphics.FromImage(outputImage);
graphics.DrawImage(img, new Rectangle(0, 0, outputWidth, outputHeight),
new Rectangle(0, 0, img.Width, img.Height), GraphicsUnit.Pixel);
return outputImage;
}
catch (Exception ex)
{
return img;
}
}

Resize and save an image to fit under width and height like a canvas keeping image proportional
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
namespace Infra.Files
{
public static class GenerateThumb
{
/// <summary>
/// Resize and save an image to fit under width and height like a canvas keeping things proportional
/// </summary>
/// <param name="originalImagePath"></param>
/// <param name="thumbImagePath"></param>
/// <param name="newWidth"></param>
/// <param name="newHeight"></param>
public static void GenerateThumbImage(string originalImagePath, string thumbImagePath, int newWidth, int newHeight)
{
Bitmap srcBmp = new Bitmap(originalImagePath);
float ratio = 1;
float minSize = Math.Min(newHeight, newHeight);
if (srcBmp.Width > srcBmp.Height)
{
ratio = minSize / (float)srcBmp.Width;
}
else
{
ratio = minSize / (float)srcBmp.Height;
}
SizeF newSize = new SizeF(srcBmp.Width * ratio, srcBmp.Height * ratio);
Bitmap target = new Bitmap((int)newSize.Width, (int)newSize.Height);
using (Graphics graphics = Graphics.FromImage(target))
{
graphics.CompositingQuality = CompositingQuality.HighSpeed;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.DrawImage(srcBmp, 0, 0, newSize.Width, newSize.Height);
using (MemoryStream memoryStream = new MemoryStream())
{
target.Save(thumbImagePath);
}
}
}
}
}

Below function will return the new size to display the image.This may not be helpful here.But it will return resized Display Rectangle size.
public static class ResizeImage
{
/// <summary>
/// Return new resized size to display the image
/// </summary>
/// <param name="srcrectanle">source rectangle of image or you can pass the bitmap and set the size accrodingly</param>
/// <param name="initSize">initial size of the page to draw image</param>
/// <returns></returns>
public static SizeF getResizedRectangle(RectangleF srcrectanle, SizeF initSize)
{
float sw = srcrectanle.Width;
float sh = srcrectanle.Height;
float dw = initSize.Width;
float dh = initSize.Height;
float finalHeight, finalWidth;
float Sourceratio = sw / sh;
if (Sourceratio >= 1)
{
finalWidth = (int)dw;
float ratio = sw / dw;
finalHeight = (sh / ratio);
}
else
{
finalHeight = (int)dh;
float ratio = sh / dh;
finalWidth = (sw / ratio);
}
return new SizeF(finalHeight, finalHeight);
}
}