For me the Aforge rectangle detection gives completely false coordinates.
Here's my code:
public List<System.Drawing.Rectangle> Detect(string path)
{
var image = GetImage(path);
var blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinWidth = 50;
blobCounter.MinHeight = 50;
blobCounter.ProcessImage(image);
var rects = blobCounter.GetObjectsRectangles();
return rects.ToList();
}
public System.Drawing.Bitmap GetImage(string path)
{
BitmapSource bSource = new BitmapImage(new Uri(path));
var image = Helpers.BitmapConverter.GetBitmap(bSource);
return image;
}
and my test image is this:
I've also tried reverting the colors, but nothing seems to help.
I always get just: {X = 16 Y = 42 Width = 51 Height = 141} That is obviously wrong for that rectangle in the image. How do I use Aforge to detect rectangles?
By using the AForge BlobCounter class GetObjectsInformation method.
Using the image provided, a snippet of the code provided in a simple Windows Forms Application with a picture box and a button I was able to detect the rectangle by drawing a lime green line over the original image using the following code.
//after pictureBox1's image has been set to the provided image.
Bitmap image = new Bitmap(pictureBox1.Image);
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinWidth = 50;
blobCounter.MinHeight = 50;
blobCounter.ProcessImage(image);
Blob[] blobs = blobCounter.GetObjectsInformation();
Blob blob = blobs[0];
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Graphics g = Graphics.FromImage(image);
Pen redPen = new Pen(Color.Red, 2);
Pen greenPen = new Pen(Color.Lime, 2);
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blob);
List<IntPoint> corners;
if (shapeChecker.IsConvexPolygon(edgePoints, out corners))
{
PolygonSubType subType = shapeChecker.CheckPolygonSubType(corners);
Pen pen;
if (subType == PolygonSubType.Unknown)
{
pen = (corners.Count == 4) ? redPen : redPen;
}
else
{
pen = greenPen;
}
System.Drawing.Point[] array = new System.Drawing.Point[corners.Count];
for (int i = 0, n = corners.Count; i < n; i++)
{
array[i] = new System.Drawing.Point(corners[i].X + 1, corners[i].Y + 1);
}
g.DrawPolygon(pen, array);
}
redPen.Dispose();
greenPen.Dispose();
g.Dispose();
pictureBox1.Image = image;
pictureBox1.Width = image.Width;
pictureBox1.Height = image.Height;
Provided Image
Processed Image
Related
I am trying to create object detection in C# windows form Project using AForge.NET.
I wrote this code:
public void DetectCorners()
{
// Load image and create everything you need for drawing
Bitmap image = new Bitmap(#"C:\Users\ssammour\Desktop\Unbenannt.PNG");
originalPicture.ImageLocation = #"C:\Users\ssammour\Desktop\Unbenannt.PNG";
BlobCounter blobCounter = new BlobCounter();
blobCounter.ProcessImage(image);
Graphics g = this.CreateGraphics();
Blob[] blobs = blobCounter.GetObjectsInformation();
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Pen redPen = new Pen(Color.Red);
for (int i = 0, n = blobs.Length; i < n; i++)
{
List<IntPoint> corners;
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blobs[i]);
if (shapeChecker.IsQuadrilateral(edgePoints, out corners))
{
g.DrawPolygon(redPen, ToPointsArray(corners));
image = new Bitmap(image.Width, image.Height, g);
}
}
// Display
newPicture.Image = image;
}
private System.Drawing.Point[] ToPointsArray(List<IntPoint> points)
{
System.Drawing.Point[] array = new System.Drawing.Point[points.Count];
return array;
}
the result is always Black photo, I don't know why.
I used this photo to try the code:
but still receive a black photo.
any help? and why is that?
and if you please can tell me how can I detect all objects inside the image.
You are not doing anything in ToPointsArray. You are just returning an array of the same length.
You should do something like this instead (I don't know IntPoint):
private System.Drawing.Point[] ToPointsArray(List<IntPoint> points)
{
System.Drawing.Point[] array = new System.Drawing.Point[points.Count];
int i = 0;
foreach (IntPoint p in points)
{
array[i++] = new System.Drawing.Point(p.X, p.Y);
}
return array;
}
Furthermore you are ruining your image in your for loop. This code works:
public void DetectCorners()
{
// Load image and create everything you need for drawing
Bitmap image = new Bitmap(#"C:\Users\ssammour\Desktop\Unbenannt.PNG");
BlobCounter blobCounter = new BlobCounter();
blobCounter.ProcessImage(image);
Bitmap result = new Bitmap(image.Width, image.Height, Graphics.FromImage(image));
Graphics g = Graphics.FromImage(result);
g.DrawImage(image,0,0);
Blob[] blobs = blobCounter.GetObjectsInformation();
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Pen redPen = new Pen(Color.Red);
for (int i = 0, n = blobs.Length; i < n; i++)
{
List<IntPoint> corners;
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blobs[i]);
if (shapeChecker.IsQuadrilateral(edgePoints, out corners))
{
corners.Dump();
g.DrawPolygon(redPen, ToPointsArray(corners, image.Height));
}
}
result.Save(#"c:\result.png", ImageFormat.Png);
}
I get these points:
(0 0),(574 0),(574 398),(0 398)
(161 391),(162 390),(165 393),(165 394)
(301 394),(304 392),(310 398),(303 398)
(552 398),(558 392),(561 392),(562 398)
(155 397),(156 396),(157 398),(155 398)
So, it looks like the BlobCounter doesn't find the blobs you are looking for.
I wrote it like this, but the rectangular bars do not appear. How can I detect these bars?
I specified the problem in the picture.
Thank you..
Bitmap bitmap = (Bitmap)panel1.BackgroundImage;
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = 1;
blobCounter.MinWidth = 1;
blobCounter.ObjectsOrder = ObjectsOrder.Size;
blobCounter.ProcessImage(bitmap);
Pen yellowPen = new Pen(Color.Red, 6);
Graphics g = Graphics.FromImage(bitmap);
Blob[] blobs = blobCounter.GetObjectsInformation();
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
foreach (var blob in blobs)
{
List<IntPoint> edgePoints = blobCounter.GetBlobsEdgePoints(blob);
List<IntPoint> cornerPoints;
if (shapeChecker.IsQuadrilateral(edgePoints, out cornerPoints))
{
if (shapeChecker.CheckPolygonSubType(cornerPoints) == PolygonSubType.RectangledTriangle)
{
List<System.Drawing.Point> Points = new List<System.Drawing.Point>();
foreach (var point in cornerPoints)
{
Points.Add(new System.Drawing.Point(point.X, point.Y));
}
g.DrawPolygon(new Pen(Color.Red, 5.0f), Points.ToArray());
bitmap.Save(#"C:\Users\OkanBerk\Desktop\result.png");
}
}
}
panel1.BackgroundImage = bitmap;
panel1.Invalidate();
https://i.stack.imgur.com/PM4mj.jpg
I want to find small black squares/rectangles in scanned sheet to:
deskewing image if needed.
remove white page margin.
Input image:
sample image 1 http://us.cdn.persiangig.com/preview/ii2jf6/2.jpg
Output image:
sample image 2 http://us.cdn.persiangig.com/preview/9ntpnc/1.jpg
My code to find square is:
Bitmap pic =(Bitmap) pictureBox1.Image;
// create filter
AForge.Imaging.Filters.Median Medianfilter = new AForge.Imaging.Filters.Median();
// apply the filter
Medianfilter.ApplyInPlace(pic);
Bitmap grayImage;
if (pic.PixelFormat != PixelFormat.Format16bppGrayScale && pic.PixelFormat != PixelFormat.Format8bppIndexed)
{
AForge.Imaging.Filters.Grayscale grayscalefilter = new AForge.Imaging.Filters.Grayscale(0.2125, 0.7154, 0.0721);
grayImage = grayscalefilter.Apply((Bitmap)pictureBox1.Image);
}
else
{
grayImage = pic;
}
// black & white:
Threshold(ref grayImage, Convert.ToInt32(textBox1.Text), Convert.ToInt32(textBox1.Text));
// invert filter
Invert invertfilter = new Invert();
// apply the filter
invertfilter.ApplyInPlace(grayImage);
// Edge Detector filter
DifferenceEdgeDetector EdgeDetectorfilter = new DifferenceEdgeDetector();
// apply the filter
EdgeDetectorfilter.ApplyInPlace(grayImage);
// create filter
Dilatation Dilatationfilter = new Dilatation();
// apply the filter
Dilatationfilter.ApplyInPlace(grayImage);
Finding object(square/rectangle) in image:
// lock image
BitmapData bitmapData = grayImage.LockBits(new Rectangle(0, 0, grayImage.Width, grayImage.Height),
ImageLockMode.ReadWrite, grayImage.PixelFormat);
// step 2 - locating objects
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = 10; //*-*-*-*-
blobCounter.MinWidth = 10;
blobCounter.MaxHeight = 50;
blobCounter.MaxWidth = 50;
blobCounter.ProcessImage(bitmapData);
Blob[] blobs = blobCounter.GetObjectsInformation();
grayImage.UnlockBits(bitmapData);
// step 3 - check objects' type and highlight
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Graphics g = Graphics.FromImage(pic);
Pen redPen = new Pen(Color.Red, 2); // quadrilateral
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]);
List<IntPoint> corners;
// is triangle or quadrilateral
if (shapeChecker.IsQuadrilateral(edgePoints, out corners))
{
// get sub-type
PolygonSubType subType = shapeChecker.CheckPolygonSubType(corners);
Pen pen;
if (subType == PolygonSubType.Square)
{
pen = (corners.Count == 4) ? bluePen : redPen;
g.DrawPolygon(pen, ToPointsArray(corners));
}
}
}
redPen.Dispose();
bluePen.Dispose();
g.Dispose();
pictureBox1.Image = pic;
Problem is low accuracy on detecting squares and rectangles!!!
How can I solve this problem?
If you can use OpenCV this is quite easy. Use the Hough transform and find peaks in the output. Those correspond to straight lines in your input.
If you can't use OpenCV, you'll need to implement it yourself. Here's something to get you started.
https://en.wikipedia.org/?title=Hough_transform
EDIT
As Anders Gustafsson points out in the comment below, the Hough Transform is available in AForge for .NET so implementing it yourself isn't a necessity.
http://www.aforgenet.com/framework/features/hough_transformation.html
I try to write simple shape detection app. I'm using sample from Aforge.net library. But I always get same error:
cannot convert from 'AForge.Point[]' to 'System.Drawing.PointF[]'
I try to change some things in ImageProcess method as well as in ToPointsArray, but effect is always the same. What else can I try? What I do wrong?
Here is code:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
try
{
ProcessImage((Bitmap)Bitmap.FromFile(openFileDialog1.FileName));
}
catch
{
MessageBox.Show("Załadowanie obrazu niepowiodło się.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
private void ProcessImage(Bitmap bitmap)
{
//-------------------------------------
BitmapData bitmapData = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
ImageLockMode.ReadWrite, bitmap.PixelFormat);
//-------------------------------------
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);
//-------------------------------------
BlobCounter blobCounter = new BlobCounter();
blobCounter.FilterBlobs = true;
blobCounter.MinHeight = 5;
blobCounter.MinWidth = 5;
blobCounter.ProcessImage(bitmapData);
Blob[] blobs = blobCounter.GetObjectsInformation();
bitmap.UnlockBits(bitmapData);
//-------------------------------------
SimpleShapeChecker shapeChecker = new SimpleShapeChecker();
Graphics g = Graphics.FromImage(bitmap);
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]);
{
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.Unknown)
{
pen = (corners.Count == 4) ? redPen : bluePen;
}
else
{
pen = (corners.Count == 4) ? brownPen : greenPen;
}
g.DrawPolygon(pen, ToPointsArray(corners));
}
}
}
redPen.Dispose();
greenPen.Dispose();
bluePen.Dispose();
brownPen.Dispose();
g.Dispose();
// put new image to clipboard
Clipboard.SetDataObject(bitmap);
// and to picture box
pictureBox1.Image = bitmap;
UpdatePictureBoxPosition();
}
private Point[] ToPointsArray(List<IntPoint> points)
{
Point[] array = new Point[points.Count];
for (int i = 0, n = points.Count; i < n; i++)
{
array[i] = new Point(points[i].X, points[i].Y);
}
return array;
}
Your problem is that AForge have there own Point struct so your ToPointArray method actually returns an Aforge Points array rather than an array of the needed .net Point. The simplest solution is to fully qualify the type you want to use, so your method would become
private System.Drawing.Point[] ToPointsArray(List<IntPoint> points)
{
System.Drawing.Point[] array = new System.Drawing.Point[points.Count];
...
}
Alternatively, if you wanted to save a few characters you could alias the namespace with a using statement at the top of the class.
using NetPoint = System.Drawing.Point;
private NetPoint ToPointsArray(List<IntPoint> points)
{
NetPoint array = new NetPoint[points.Count];
...
}
As a side note this method could be shortened if linq is available to use. For example,
private System.Drawing.Point[] ToPointsArray(List<IntPoint> points)
{
return points.Select(p => new System.Drawing.Point(p.X, p.Y)).ToArray();
}
DrawImage method of Graphics class is not creating high quality images. In this method I am splitting a master image into multiple image but the code generating first image in very low quality. But it is generating full black images for remaining height.
public static Bitmap[] Split(byte[] ByteImage)
{
// MasterImage: there is no problem in master image. it is saving it in good quality.
MemoryStream ms = new MemoryStream(ByteImage);
System.Drawing.Image MasterImage = System.Drawing.Image.FromStream(ms);
MasterImage.Save(HttpContext.Current.Server.MapPath("../../../App_Shared/Reports/Temp/MasterImage.Bmp"), ImageFormat.Bmp);
//Split master image into multiple image according to height / 1000
Int32 ImageHeight = 1000, ImageWidth = MasterImage.Width, MasterImageHeight = MasterImage.Height;
int PageCount = 0;
Int32 TotalPages = MasterImage.Height / 1000;
Bitmap[] imgs = new Bitmap[TotalPages];
for (int y = 0; y + 1000 < MasterImageHeight; y += 1000, PageCount++)
{
imgs[PageCount] = new Bitmap(ImageWidth, ImageHeight, PixelFormat.Format32bppPArgb);
using (Graphics gr = Graphics.FromImage(imgs[PageCount]))
{
gr.CompositingQuality = CompositingQuality.HighQuality;
gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
gr.SmoothingMode = SmoothingMode.HighQuality;
//First image now working with this code line
gr.DrawImage(MasterImage, new System.Drawing.Rectangle(0, y, ImageWidth, ImageHeight),new System.Drawing.Rectangle(0, 0, ImageWidth, ImageHeight), GraphicsUnit.Pixel); //new System.Drawing.Rectangle(new Point(0, y), new Size(ImageWidth, ImageHeight)));
//gr.DrawImage(MasterImage, new System.Drawing.Rectangle(0, y, ImageWidth, ImageHeight)); //new System.Drawing.Rectangle(new Point(0, y), new Size(ImageWidth, ImageHeight)));
string FilePath = HttpContext.Current.Server.MapPath("../../../App_Shared/Reports/Temp/Image" + PageCount.ToString() + ".bmp");
imgs[PageCount].Save(FilePath, System.Drawing.Imaging.ImageFormat.Bmp);
//Here it is saving images. I got first image with very poor quality but remaining in total balck color.
gr.Dispose();
}
}
return imgs;
}
As #HansPassant mentioned the source and target rectangle are reversed.
You could also change the structure of your splitting a bit so it could work a bit more flexible, and it might have a better readability at a later time.
class Program
{
static IList<Bitmap> SplitImage(Bitmap sourceBitmap, int splitHeight)
{
Size dimension = sourceBitmap.Size;
Rectangle sourceRectangle = new Rectangle(0, 0, dimension.Width, splitHeight);
Rectangle targetRectangle = new Rectangle(0, 0, dimension.Width, splitHeight);
IList<Bitmap> results = new List<Bitmap>();
while (sourceRectangle.Top < dimension.Height)
{
Bitmap pageBitmap = new Bitmap(targetRectangle.Size.Width, sourceRectangle.Bottom < dimension.Height ?
targetRectangle.Size.Height
:
dimension.Height - sourceRectangle.Top, PixelFormat.Format32bppArgb);
using (Graphics g = Graphics.FromImage(pageBitmap))
{
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear;
g.DrawImage(sourceBitmap, targetRectangle, sourceRectangle, GraphicsUnit.Pixel);
}
sourceRectangle.Y += sourceRectangle.Height;
results.Add(pageBitmap);
}
return results;
}
static void Main(string[] args)
{
string sourceFilename = Environment.CurrentDirectory + #"\testimage.jpg";
Bitmap sourceBitmap = (Bitmap)Image.FromFile(sourceFilename);
var images = SplitImage(sourceBitmap, 79);
int len = images.Count;
for (int x = len; --x >= 0; )
{
var bmp = images[x];
string filename = "Images-" + x + ".bmp";
bmp.Save(Environment.CurrentDirectory + #"\" + filename, ImageFormat.Bmp);
images.RemoveAt(x);
bmp.Dispose();
Console.WriteLine("Saved " + filename);
}
Console.WriteLine("Done with the resizing");
}
}
This would also dynamically size the last image in case the page is less than your specified bitmap height at the end :)