c# - 超正方体 OCR : very inaccurate result

Question

下面是我用来测试 Tesseract 性能的非常简单的程序。尽管图片是高质量且非常清晰的屏幕截图(不是带有颜色的复杂图片)，但我得到的结果并不像预期的那样。请查看我的代码和下面的结果。我不确定是我做错了什么还是 Tesseract 引擎无法处理这个？

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using tessnet2;

namespace ImageProcessTesting
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        int up_lef_x = 1075;
        int up_lef_y = 0070;

        int bo_rig_x = 1430;
        int bo_rig_y = 0095;

        int width = bo_rig_x - up_lef_x;
        int height = bo_rig_y - up_lef_y;

        var bmpScreenshot = new Bitmap(width, height, PixelFormat.Format32bppArgb);
        var gfxScreenshot = Graphics.FromImage(bmpScreenshot);

        gfxScreenshot.CopyFromScreen(
                                    1075,
                                    0070,
                                    0,
                                    0,
                                    Screen.PrimaryScreen.Bounds.Size,
                                    CopyPixelOperation.SourceCopy);

        // bmpScreenshot.Save("C:\\Users\\Exa\\Screenshot.png", ImageFormat.Png);


        var image = bmpScreenshot;
        var ocr = new Tesseract();
        ocr.Init(@"C:\Users\Exa\Desktop\tessdata", "eng", false);
        var result = ocr.DoOCR(image, Rectangle.Empty);
        string result_str = "";
        foreach (Word word in result)
            result_str += word.Text;
        MessageBox.Show(result_str);

    }
}
}

Answer 1

96DPI 的屏幕截图通常不足以进行 OCR。正如写在Tesseract wiki :

There is a minimum text size for reasonable accuracy. You have to consider resolution as well as point size. Accuracy drops off below 10pt x 300dpi, rapidly below 8pt x 300dpi. A quick check is to count the pixels of the x-height of your characters. (X-height is the height of the lower case x.) At 10pt x 300dpi x-heights are typically about 20 pixels, although this can vary dramatically from font to font. Below an x-height of 10 pixels, you have very little chance of accurate results, and below about 8 pixels, most of the text will be "noise removed".

但是，如果您知道确切的字体是什么，您可以尝试重新训练 tesseract 以获得更好的结果。