OCR Image Color Editing
using IronOcr;
using IronSoftware.Drawing;
using System;

var ocrTesseract = new IronTesseract();

using var ocrInput = new OcrInput();
ocrInput.LoadImage("blue_and_pink.png");

ocrInput.WithTitle("Recolored");

ocrInput.ReplaceColor(Color.Pink, Color.White, 10);
// Pink detection has 10% tolerance

ocrInput.ReplaceColor(Color.Blue, Color.Black, 5);
// Blue detection has 5% tolerance

// Export the modified image so you can manually inspect it.
foreach (var page in ocrInput.GetPages())
{
    page.SaveAsImage($"black_and_white_page_{page.Index}.bmp");
}

var ocrResult = ocrTesseract.Read(ocrInput);
Console.WriteLine(ocrResult.Text);
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OCR Image Color Editing

OCR Image Color Editing

OCR works faster and more accurately when we read black text on a white background.

If we have, for example, blue text on a pink background, we will want to swap blue to black and pink to white before performing OCR.

This can be very time-consuming and slow using System.Drawing, but it is completely automated with IronOCR.

The OcrInput.ReplaceColor method allows us to replace one color with another in a document. This method is adaptive, allowing you to specify a percentage tolerance for a match to an exact RGB color. This removes the need to use Photoshop or ImageMagick scripts to prepare images for OCR.

ReplaceColor Method Parameters

  • The first parameter is the color to be replaced.
  • The second parameter is the replacement color.
  • The third optional parameter specifies tolerance for how closely the colors must match, which allows for variations within the specified percentage.
Learn More About Image Color Correction in OCR
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