I'm trying to use a tesseract in project wrote in C#. I have a problem with
reading text from a part of an image. I'm trying to find this 4 signs (in
example 0000) and number after "e". Additionally, for some examples it is
working perfectly but for some others its printing "Empty page!!!".
Difference between examples is color of the background but whole image
processing is the same for every try. What should I do to minimize
probability of error?
Thats the image where ocr is working correctly:
[image: working.jpg]
and here is not working:
[image: not working.jpg]
Part of code in c#:
public static class Sign
{
public static void Verify()
{
string imagePath = "path.bmp";
Mat imageSign = new Mat(imagePath);
int h = imageSign.Rows;
int w = imageSign.Cols;
int point1 = (int)(0.01 * w);
int point2 = (int)(0.6 * h);
int point3 = (int)(0.3 * w);
int point4 = (int)(0.9 * h);
OpenCvSharp.Point start_point = new OpenCvSharp.Point(point1,
point2);
OpenCvSharp.Point end_point = new OpenCvSharp.Point(point3, point4);
imageSign = new Mat(imageSign, new OpenCvSharp.Rect(point1, point2,
point3 - point1, point4 - point2));
Cv2.Resize(imageSign, imageSign, new OpenCvSharp.Size(), 2, 2);
imageSign.SaveImage(imagePath);
using (Bitmap bitmap = (Bitmap)Image.FromFile(imagePathE))
{
using (Bitmap newBitmap = new Bitmap(bitmap))
{
string imagePathA = "2nd image path.bmp";
newBitmap.SetResolution(300, 300);
newBitmap.Save(imagePathA);
}
}
string imagePathB = " "2nd image path.bmp " ;
var pixFromFile = Pix.LoadFromFile(imagePathB);
string customConfig = "--psm 10 --oem 3";
using (var engine = new TesseractEngine(@"C:\Program
Files\Tesseract-OCR\tessdata", "eng", EngineMode.Default))
{
engined.SetVariable("tessedit_char_whitelist", "0123456789");
using (var page = engined.Process(pixFromFile, customConfig))
{
string text = page.GetText();
Console.Write(text);
string[] lines = text.Split('\n');
bool linijka = false;
foreach (string line in lines)
{
if (line.Length == 4 || line.Length == 5)
{
Console.WriteLine("Oznaczenie e5: ");
Console.WriteLine(line);
linijka = true;
}
if (line.Length == 1)
{
Console.WriteLine("e_:");
Console.WriteLine(line);
}
}
Cv2.ImShow("koniec", imageSign);
Cv2.WaitKey(0);
}
}
I tried cropping an image and for some reason when i making it bigger or
smaller than it is now, it adversely affects on results. Additionally I
tried some other tesseract psm configurations and changed dpi of image to
300.
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