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Try some more algorithms

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We got the black background, receipt foreground working, but this is a limited test case. I do not have something working in the general case nor the expertise to know how to do that.
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Michael Babienco
2026-03-01 15:26:36 +09:00
parent 7b854d7216
commit 00d35a5ead
2 changed files with 175 additions and 10 deletions
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TODO.txt
+1
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@@ -13,6 +13,7 @@
-https://github.com/shimat/opencvsharp
-https://www.emgu.com/wiki/index.php?title=Main_Page (GPL...)
-https://stackoverflow.com/questions/30296710/detecting-paper-edge-and-crop-it
//https://developers.goalist.co.jp/entry/2019/02/13/150126
---------------
src/ViewModels/MainViewModel.cs
+174 -10
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@@ -21,6 +21,9 @@ using MayShow.Interfaces;
using MayShow.Models;
using MayShows.Helpers;
using OpenCvSharp;
using System.Reflection.Metadata.Ecma335;
using System.Collections.Generic;
using System.Threading;
namespace MayShow.ViewModels;
@@ -519,22 +522,183 @@ class MainViewModel : BaseViewModel, IFontResolver, ICanCheckShutdown
public void TestReceiptFinding(object f) => TestReceiptFindingImpl((ReportFile)f);
private Mat? b_algor(ReportFile file)
{
using var orig = new Mat(file.FilePath);
using var src = new Mat(file.FilePath, ImreadModes.Grayscale);
if (src.Empty())
{
LogInfo("File was empty?");
return null;
}
using var blur = orig.GaussianBlur(new Size(5, 5), 0.0);
using var kernel = Cv2.GetStructuringElement(MorphShapes.Rect, new Size(9,9));
using var dilated = blur.Dilate(kernel, anchor: null, iterations: 4);
using var edges = dilated.Canny(100, 200, 3);
using var heirarchy = new Mat();
Cv2.FindContours(edges, out Mat[] contours, heirarchy, RetrievalModes.External, ContourApproximationModes.ApproxSimple);
using var orgWithContours = new Mat();
orig.CopyTo(orgWithContours);
Cv2.DrawContours(orgWithContours, contours, -1, Scalar.Cyan, 3);
// largest contours
var largestContours = contours.OrderByDescending(x => x.ContourArea()).Take(1).ToArray();
var orgWithLargestContours = new Mat();
orig.CopyTo(orgWithLargestContours);
Cv2.DrawContours(orgWithLargestContours, largestContours, -1, Scalar.Cyan, 5);
using (new OpenCvSharp.Window("blur", blur))
using (new OpenCvSharp.Window("dilated", dilated))
using (new OpenCvSharp.Window("edges", edges))
using (new OpenCvSharp.Window("contours", orgWithContours))
// using (new OpenCvSharp.Window("w biggest contours", orgWithBiggestContours))
{
Cv2.WaitKey();
}
return orgWithLargestContours;
}
private void TestReceiptFindingImpl(ReportFile file)
{
LogInfo("Running receipt edge detection...");
LogInfo("Running receipt edge detection on file at path {0} with OpenCV {1}...", file.FilePath, Cv2.GetVersionString() ?? "");
using var orig = new Mat(file.FilePath);
using var src = new Mat(file.FilePath, ImreadModes.Grayscale);
using var dst = new Mat();
using var blur = new Mat();
using var dilated = new Mat();
Cv2.GaussianBlur(src, blur, new OpenCvSharp.Size(5.0, 5.0), 0.0, 0.0, BorderTypes.Constant);
// Cv2.Threshold(dst, dst, 160, 255, ThresholdTypes.Binary & ThresholdTypes.Otsu);
using var wContours = new Mat();
if (src.Empty())
{
LogInfo("File was empty?");
return;
}
var threshold = src.Threshold(90,255, ThresholdTypes.Binary);
var blur = orig.GaussianBlur(new Size(3.0, 3.0), 0.0);
var kernel = Cv2.GetStructuringElement(MorphShapes.Rect, new Size(9,9));
Cv2.Dilate(blur, dilated, kernel);
Cv2.Canny(dilated, dst, 40, 60, 3);
var dilated = blur.Dilate(kernel, null, 1);
var edges = dilated.Canny(50, 200, 3);
//# Detect all contours in Canny-edged image
using var heirarchy = new Mat();
Cv2.FindContours(threshold, out Mat[] contours, heirarchy, RetrievalModes.External, ContourApproximationModes.ApproxSimple);
var orgWithContours = new Mat();
orig.CopyTo(orgWithContours);
Cv2.DrawContours(orgWithContours, contours, -1, Scalar.Cyan, 3);
// # find full contours
var poly = new List<Mat>();
foreach (var contour in contours)
{
var hull = contour.ConvexHull();
poly.Add(hull.ApproxPolyDP(0.01 * Cv2.ArcLength(hull, true), false));
}
Console.WriteLine("How many? {0}", poly.Count);
var orgWithAllPly = new Mat();
orig.CopyTo(orgWithAllPly);
Cv2.DrawContours(orgWithAllPly, poly, -1, Scalar.Red, 3);
var largestPoly = poly.OrderByDescending(x => x.ContourArea()).Take(10).ToArray();
var orgWithLargestContoursPly = new Mat();
orig.CopyTo(orgWithLargestContoursPly);
Cv2.DrawContours(orgWithLargestContoursPly, largestPoly, -1, Scalar.Red, 5);
// using (new OpenCvSharp.Window("poly", orgWithAllPly))
// using (new OpenCvSharp.Window("pol2y", orgWithLargestContoursPly))
// {
// Cv2.WaitKey();
// }
//
// # Get 10 largest contours
Console.WriteLine(contours);
var orgWithLargestContours = new Mat();
orig.CopyTo(orgWithLargestContours);
var largestContours = contours.OrderByDescending(x => x.ContourArea()).Take(10).ToArray();
Cv2.DrawContours(orgWithLargestContours, largestContours, -1, Scalar.Cyan, 5);
//
Mat approximate_contour(Mat contour)
{
var perimeter = Cv2.ArcLength(contour, true);
return contour.ApproxPolyDP(0.02 * perimeter, true);
}
Mat? get_receipt_counter(Mat[] contours)
{
var poly = new List<Mat>();
foreach (var contour in contours)
{
// var hull = contour.ConvexHull();
// var arcLength = hull.ArcLength(true);
// var x = contour.ApproxPolyDP(0.01 * arcLength, true);
// poly.Add(x);
var approx = approximate_contour(contour);
if (approx.Total() == 4)
{
return approx;
}
}
return null;
}
var highestY = 0;
var lowestY = 9999;
var highestX = 0;
var lowestX = 9999;
foreach (var contour in largestContours)
{
Console.WriteLine("Rows: {0}", contour.Rows);
if (contour.Rows > 10) // eliminate small things?
{
for (var i = 0; i < contour.Rows; i++)
{
var pt = contour.At<Point>(i);
if (pt.X < lowestX)
{
lowestX = pt.X;
}
if (pt.X > highestX)
{
highestX = pt.X;
}
if (pt.Y < lowestY)
{
lowestY = pt.Y;
}
if (pt.Y > highestY)
{
highestY = pt.Y;
}
}
}
}
Console.WriteLine("Low X: {0}, High X: {1}", lowestX, highestX);
Console.WriteLine("Low Y: {0}, High Y: {1}", lowestY, highestY);
var rect = new Rect(lowestX, lowestY, Math.Abs(highestX - lowestX), Math.Abs(highestY - lowestY));
Console.WriteLine(rect);
using var crop = new Mat(orig, rect);
using (new OpenCvSharp.Window("w largest contours", orgWithLargestContours))
using (new OpenCvSharp.Window("crop", crop))
using (new OpenCvSharp.Window("crop_b", b_algor(file)))
// using (new OpenCvSharp.Window("w biggest contours", orgWithBiggestContours))
{
Cv2.WaitKey();
}
return;
var largest = get_receipt_counter(largestContours);
Console.WriteLine(largest);
var orgWithBiggestContours = new Mat();
orig.CopyTo(orgWithBiggestContours);
Cv2.DrawContours(orgWithBiggestContours, [largest], -1, Scalar.Cyan, 3);
////
using (new OpenCvSharp.Window("src image", src))
using (new OpenCvSharp.Window("blur image", blur))
using (new OpenCvSharp.Window("dilated image", dilated))
using (new OpenCvSharp.Window("dst image", dst))
// using (new OpenCvSharp.Window("blur image", blur))
// using (new OpenCvSharp.Window("dilated image", dilated))
using (new OpenCvSharp.Window("orig with all contours", orgWithContours))
using (new OpenCvSharp.Window("w largest contours", orgWithLargestContours))
// using (new OpenCvSharp.Window("w biggest contours", orgWithBiggestContours))
{
Cv2.WaitKey();
}