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How to Resize Center and Crop an image with ImageSharp

I need to convert some System.Drawing based code to use this .NET Core compatible library:
https://github.com/SixLabors/ImageSharp
The System.Drawing based code below resizes an image and crops of the edges, returning the memory stream to then be saved. Is this possible with the ImageSharp library?
private static Stream Resize(Stream inStream, int newWidth, int newHeight)
{
var img = Image.Load(inStream);
if (newWidth != img.Width || newHeight != img.Height)
{
var ratioX = (double)newWidth / img.Width;
var ratioY = (double)newHeight / img.Height;
var ratio = Math.Max(ratioX, ratioY);
var width = (int)(img.Width * ratio);
var height = (int)(img.Height * ratio);
var newImage = new Bitmap(width, height);
Graphics.FromImage(newImage).DrawImage(img, 0, 0, width, height);
img = newImage;
if (img.Width != newWidth || img.Height != newHeight)
{
var startX = (Math.Max(img.Width, newWidth) - Math.Min(img.Width, newWidth)) / 2;
var startY = (Math.Max(img.Height, newHeight) - Math.Min(img.Height, newHeight)) / 2;
img = Crop(img, newWidth, newHeight, startX, startY);
}
}
var ms = new MemoryStream();
img.Save(ms, ImageFormat.Jpeg);
ms.Position = 0;
return ms;
}
private static Image Crop(Image image, int newWidth, int newHeight, int startX = 0, int startY = 0)
{
if (image.Height < newHeight)
newHeight = image.Height;
if (image.Width < newWidth)
newWidth = image.Width;
using (var bmp = new Bitmap(newWidth, newHeight, PixelFormat.Format24bppRgb))
{
bmp.SetResolution(72, 72);
using (var g = Graphics.FromImage(bmp))
{
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.DrawImage(image, new Rectangle(0, 0, newWidth, newHeight), startX, startY, newWidth, newHeight, GraphicsUnit.Pixel);
var ms = new MemoryStream();
bmp.Save(ms, ImageFormat.Jpeg);
image.Dispose();
var outimage = Image.FromStream(ms);
return outimage;
}
}
}

Yeah, super easy.
using (var inStream = ...)
using (var outStream = new MemoryStream())
using (var image = Image.Load(inStream, out IImageFormat format))
{
image.Mutate(
i => i.Resize(width, height)
.Crop(new Rectangle(x, y, cropWidth, cropHeight)));
image.Save(outStream, format);
}
EDIT
If you want to leave the original image untouched you can use the Clone method instead.
using (var inStream = ...)
using (var outStream = new MemoryStream())
using (var image = Image.Load(inStream, out IImageFormat format))
{
var clone = image.Clone(
i => i.Resize(width, height)
.Crop(new Rectangle(x, y, cropWidth, cropHeight)));
clone.Save(outStream, format);
}
You might even be able to optimize this into a single method call to Resize via the overload that accepts a ResizeOptions instance with `ResizeMode.Crop. That would allow you to resize to a ratio then crop off any excess outside that ratio.

So here's relevent code after so far after converting to not use original methods:
using (var fullSizeStream = new MemoryStream())
using (var smallStream = new MemoryStream())
using (var thumbStream = new MemoryStream())
using (var reviewThumbStream = new MemoryStream())
using (var image = Image.Load(inStream))
{
// Save original constrained
var clone = image.Clone(context => context
.Resize(new ResizeOptions
{
Mode = ResizeMode.Max,
Size = new Size(1280, 1280)
}));
clone.Save(fullSizeStream, new JpegEncoder { Quality = 80 });
//Save three sizes Cropped:
var jpegEncoder = new JpegEncoder { Quality = 75 };
clone = image.Clone(context => context
.Resize(new ResizeOptions
{
Mode = ResizeMode.Crop,
Size = new Size(277, 277)
}));
clone.Save(smallStream, jpegEncoder);
clone = image.Clone(context => context
.Resize(new ResizeOptions
{
Mode = ResizeMode.Crop,
Size = new Size(100, 100)
}));
clone.Save(thumbStream, jpegEncoder);
clone = image.Clone(context => context
.Resize(new ResizeOptions
{
Mode = ResizeMode.Crop,
Size = new Size(50, 50)
}));
clone.Save(reviewThumbStream, jpegEncoder);
//...then I just save the streams to blob storage
}

RenderTargetBitmap low image quality issue

I try to generate 300 dpi image using RenderTargetBitmap method.
When I try to use RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap(315, 195, 300, 300, PixelFormats.Pbgra32);
Image gets extremly big.
How to fix it?
RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap(315, 195, 96, 96, PixelFormats.Pbgra32);
renderTargetBitmap.Render(gridCard);
PngBitmapEncoder pngImage = new PngBitmapEncoder();
pngImage.Frames.Add(BitmapFrame.Create(renderTargetBitmap));
using (Stream fileStream = File.Create(path))
{
pngImage.Save(fileStream);
}

I need to scale the bitmap's size by the desired DPI (i.e. 300) divided by the default DPI (i.e. 96).
double w = 315;
double h = 195;
double dpi = 300;
double scale = dpi / 96;
RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap(
(int)(w * scale), (int)(h * scale), dpi, dpi, PixelFormats.Pbgra32);
UPDATE #1 Full solution (to print WPF Control is proxi-card to special printer MAGiCARD Enduro 3E)
private void BtnPrint_Click(object sender, RoutedEventArgs e)
{
try
{
var size = GetElementPixelSize(gridCard);
double w = size.Width;
double h = size.Height;
double dpiScale = 300.0 / 99.9;
double dpiX = 300.0;
double dpiY = 300.0;
RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap(Convert.ToInt32((w) * dpiScale), Convert.ToInt32((h) * dpiScale), dpiX, dpiY, PixelFormats.Pbgra32);
renderTargetBitmap.Render(gridCard);
PngBitmapEncoder pngImage = new PngBitmapEncoder();
pngImage.Frames.Add(BitmapFrame.Create(renderTargetBitmap));
var biRotated = new BitmapImage();
using (Stream fileStream = new MemoryStream())
{
pngImage.Save(fileStream);
fileStream.Seek(0, SeekOrigin.Begin);
biRotated.BeginInit();
biRotated.CacheOption = BitmapCacheOption.OnLoad;
biRotated.StreamSource = fileStream;
// biRotated.Rotation = Rotation.Rotate90; // if you need it
biRotated.EndInit();
}
var vis = new DrawingVisual();
var dc = vis.RenderOpen();
dc.DrawImage(biRotated, new Rect { Width = biRotated.Width, Height = biRotated.Height });
dc.Close();
var pdialog = new System.Windows.Controls.PrintDialog();
if (pdialog.ShowDialog() == true)
{
pdialog.PrintVisual(vis, "Proxy-card");
}
}
catch (Exception ex)
{
System.Windows.MessageBox.Show("Print error " + ex.Message);
}
}
// https://stackoverflow.com/questions/3286175/how-do-i-convert-a-wpf-size-to-physical-pixels
public Size GetElementPixelSize(UIElement element)
{
Matrix transformToDevice;
var source = PresentationSource.FromVisual(element);
if (source != null)
transformToDevice = source.CompositionTarget.TransformToDevice;
else
{
// IntPtr hWnd = source.Handle;
using (var source1 = new HwndSource(new HwndSourceParameters()))
{
transformToDevice = source1.CompositionTarget.TransformToDevice;
}
}
if (element.DesiredSize == new Size())
element.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
return (Size)transformToDevice.Transform((Vector)element.DesiredSize);
}

Export WPF ScrollViewer content as separate PNGs

In my WPF application I have a ScrollViewer which is dynamically populated by DataBinding and the use of a UserControl. Imagine that my UserControl is something simple that only contains a label, and the value displayed in the label comes from a list. So when I run the application it looks like below:
As you can see there are multiple instances of the UserControl each with a different value that is dynamically populated. My goal is to export each of the UserControls as a separate PNG. My EXPORT PNG button click should do this.
So I looked around and found this example which works fine for exporting the entire content of the ScorllViewer.
So I tried modifying it to achieve my goal, and I do get it to work to a certain extent, but not quite what I want.
Here's my code:
private void ExportPNG()
{
var dir = Directory.GetCurrentDirectory();
var file = "ITEM_{0}.PNG";
var height = 100.0; // Height of the UserControl
var width = mainSV.ActualWidth;
for (int i = 1; i <= ItemList.Count; i++)
{
var path = System.IO.Path.Combine(dir, string.Format(file, i));
Size size = new Size(width, height);
UIElement element = mainSV.Content as UIElement;
element.Measure(size);
element.Arrange(new Rect(new Point(0, 0), size));
RenderTargetBitmap renderTarget = new RenderTargetBitmap((int)width, (int)height, 96, 96, PixelFormats.Pbgra32);
VisualBrush sourceBrush = new VisualBrush(element);
DrawingVisual drawingVisual = new DrawingVisual();
DrawingContext drawingContext = drawingVisual.RenderOpen();
using (drawingContext)
{
drawingContext.DrawRectangle(sourceBrush, null, new Rect(new Point(0, 0), new Point(width, height)));
}
renderTarget.Render(drawingVisual);
PngBitmapEncoder encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(renderTarget));
using (FileStream stream = new FileStream(path, FileMode.Create, FileAccess.Write))
{
encoder.Save(stream);
}
}
}
Now this exports 5 PNGs (when my list has 5 items), bu they all contain the image of the first element:
And I figure the problem is likely where I do the drawingContext.DrawRectangle() because my rectanble coordinates are always the same. So I tried changing it to the following, which I thought should work, but for some reason it just generates one PNG with the first UserControl and 4 empty PNGs.
using (drawingContext)
{
drawingContext.DrawRectangle(sourceBrush, null, new Rect(new Point(0, (i-1) * height), new Point(width, height + ((i-1) * height))));
}
And the result:
What am I doing wrong here?
If you would like to run the code please find it here.

Please check below two methods. I tested it and it is working very well.
1. First, find children from you Items controls
2. Convert them to PNGs.
private void ExportPNG()
{
var dir = Directory.GetCurrentDirectory();
var file = "ITEM_{0}.PNG";
var height = 100.0;
var width = 100.0;
var children = GetChildrenOfType<UCDisplayItem>(itC);
foreach (var item in children)
{
var path = System.IO.Path.Combine(dir, string.Format(file, DateTime.Now.Ticks));
Size size = new Size(width, height);
UIElement element = item as UIElement;
element.Measure(size);
element.Arrange(new Rect(new Point(0, 0), size));
RenderTargetBitmap renderTarget = new RenderTargetBitmap((int)width, (int)height, 96, 96, PixelFormats.Pbgra32);
VisualBrush sourceBrush = new VisualBrush(element);
DrawingVisual drawingVisual = new DrawingVisual();
DrawingContext drawingContext = drawingVisual.RenderOpen();
using (drawingContext)
{
drawingContext.DrawRectangle(sourceBrush, null, new Rect(new Point(0, 0), new Point(width, height)));
//drawingContext.DrawRectangle(sourceBrush, null, new Rect(new Point(0, (i - 1) * height), new Point(width, height + ((i - 1) * height))));
}
renderTarget.Render(drawingVisual);
PngBitmapEncoder encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(renderTarget));
using (FileStream stream = new FileStream(path, FileMode.Create, FileAccess.Write))
{
encoder.Save(stream);
}
}
}
public List<T> GetChildrenOfType<T>( DependencyObject depObj)
where T : DependencyObject
{
var result = new List<T>();
if (depObj == null) return null;
var queue = new Queue<DependencyObject>();
queue.Enqueue(depObj);
while (queue.Count > 0)
{
var currentElement = queue.Dequeue();
var childrenCount = VisualTreeHelper.GetChildrenCount(currentElement);
for (var i = 0; i < childrenCount; i++)
{
var child = VisualTreeHelper.GetChild(currentElement, i);
if (child is T)
result.Add(child as T);
queue.Enqueue(child);
}
}
return result;
}
RESULT

Blob doesn`t match tracking object

hi,
I need to use color tracking.
The blob does not match my target object when I run my code in surface pro 4.
but the code is correct when I test it on my Acer.
anyone knows that why?
public void forobject(Bitmap image)//put setted color value into image1
{
BlobCounter blobCounter = new BlobCounter();
blobCounter.MinWidth = 5;
blobCounter.MinHeight = 5;
blobCounter.FilterBlobs = true;
blobCounter.ObjectsOrder = ObjectsOrder.Size;
//Grayscale griFiltre = new Grayscale(0.2125, 0.7154, 0.0721);
//Grayscale griFiltre = new Grayscale(0.2, 0.2, 0.2);
//Bitmap griImage = griFiltre.Apply(image);
BitmapData objectsData = image.LockBits(new Rectangle(0, 0, image.Width/2, image.Height/2), ImageLockMode.ReadOnly, image.PixelFormat);
// grayscaling
Grayscale grayscaleFilter = new Grayscale(0.2125, 0.7154, 0.0721);
UnmanagedImage grayImage = grayscaleFilter.Apply(new UnmanagedImage(objectsData));
// unlock image
image.UnlockBits(objectsData);
blobCounter.ProcessImage(image);
Rectangle[] rects = blobCounter.GetObjectsRectangles();
Blob[] blobs = blobCounter.GetObjectsInformation();
pictureBox_tracking.Image = image;//？？？？
if (rdiobtn_singletracking.Checked)
{
// Single Tracking--------
foreach (Rectangle recs in rects)
{
if (rects.Length > 0)
{
Rectangle objectRect = rects[0];
//Graphics g = Graphics.FromImage(image);
Graphics g = pictureBox_real.CreateGraphics();
using (Pen pen = new Pen(Color.FromArgb(252, 3, 26), 2))
{
g.DrawRectangle(pen, objectRect);
}
//Drawn by the rectangle coordinates is taken away.
//int objectX = objectRect.X; //+ (objectRect.Width / 2);
//int objectY = objectRect.Y; //+ (objectRect.Height / 2);
x = objectRect.X;
y = objectRect.Y;
w = objectRect.Width;
h = objectRect.Height;
// g.DrawString(objectX.ToString() + "X" + objectY.ToString(), new Font("Arial", 12), Brushes.Red, new System.Drawing.Point(250, 1));
g.Dispose();
}

Auto crop a rectangle

I want to auto crop the image which I took it from tablet camera. Actually I want to take the picture of id cards and need to auto corp it, I am using black background but sometimes it is too glaze and there is a reflection also, at that time its not cropped properly. Can anyone assist me with c# code to crop the images(Note : I am using phone cameras to take the image of id cards, mostly the background will be black and sometime it will be some other things).
Below I mentioned my code also:
private void ProcessImage(Bitmap bitmap)
{
// lock image
BitmapData bitmapData = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
ImageLockMode.ReadWrite, bitmap.PixelFormat);
// step 1 - turn background to black
ColorFiltering colorFilter = new ColorFiltering();
colorFilter.Red = new IntRange(0, 64);
colorFilter.Green = new IntRange(0, 64);
colorFilter.Blue = new IntRange(0, 64);
colorFilter.FillOutsideRange = false;
colorFilter.ApplyInPlace(bitmapData);
// step 2 - locating objects
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = 5;
blobCounter.MinWidth = 5;
blobCounter.ProcessImage(bitmapData);
Blob[] blobs = blobCounter.GetObjectsInformation();
bitmap.UnlockBits(bitmapData);
// step 3 - check objects' type and highlight
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Graphics g = Graphics.FromImage(bitmap);
Pen yellowPen = new Pen(Color.Yellow, 2); // circles
Pen redPen = new Pen(Color.Red, 2); // quadrilateral
Pen brownPen = new Pen(Color.Brown, 2); // quadrilateral with known sub-type
Pen greenPen = new Pen(Color.Green, 2); // known triangle
Pen bluePen = new Pen(Color.Blue, 2); // triangle
for (int i = 0, n = blobs.Length; i < n; i++)
{
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blobs[i]);
DoublePoint center;
double radius;
List<IntPoint> corners;
// is triangle or quadrilateral
if (shapeChecker.IsConvexPolygon(edgePoints, out corners))
{
// get sub-type
PolygonSubType subType = shapeChecker.CheckPolygonSubType(corners);
Pen pen;
if (subType == PolygonSubType.Rectangle)
{
pen = (corners.Count == 4) ? redPen : bluePen;
}
else
{
pen = (corners.Count == 4) ? brownPen : greenPen;
}
//g.DrawPolygon( pen, ToPointsArray( corners ) );
if (pen.Color.Name == "Red")
{
int intdummy = 0;
g.DrawRectangle(pen, corners[0].X, corners[0].Y, 1150, 750);
//Code for corpping///////
pictureBox2.Image = bitmap;
pictureBox2.SizeMode = PictureBoxSizeMode.StretchImage;
Bitmap croppedBitmap = new Bitmap("E:\\xxx\\Vicas Tablet\\WinImager\\cropimage\\cropimage\\Testing Images\\Image1.jpg");
//croppedBitmap = croppedBitmap.Clone(new Rectangle(corners[0].X, corners[0].Y,1150,750),System.Drawing.Imaging.PixelFormat.DontCare);
croppedBitmap = croppedBitmap.Clone(
new Rectangle(corners[0].X, corners[0].Y, ((int)corners[1].X - (int)corners[0].X), ((int)corners[2].Y - (int)corners[1].Y)), System.Drawing.Imaging.PixelFormat.DontCare);
pictureBox2.Image = croppedBitmap;
////End code for cropping///////////
}
}