Out of Memory exception when reading bitmap

Question

I'm get an out of memory exception when TessNet2 reads my bitmap. It happens specifically at the tessocr.GetThresholdedImage(bmp, System.Drawing.Rectangle.Empty).Save("c:\\temp\\" + Guid.NewGuid().ToString() + ".bmp"); line.

This doesn't happen all the time, it seems to happen only when I've run the program a few times in debug mode (I haven't tried packaging the code into an exe yet). This is a console application.

I've read about using bmp.UnlockBits(bmpData) but when I put that code in; I get a Bitmap region is already locked error when it hits the tessocr.GetThresholdedImage(bmp, System.Drawing.Rectangle.Empty).Save("c:\\temp\\" + Guid.NewGuid().ToString() + ".bmp"); line.

for (int p = 0; p < pdfFiles.Count(); p++)
{
    images.Read(@"c:\temp\pdfs\" + pdfFiles[p].Name, settings);

    int pageNumber = 1;
    string pdfName = pdfFiles[p].Name;

    //__loop through each page of pdfFile
    foreach (MagickImage image in images)
    {                                   
        using (Bitmap bmp = image.ToBitmap())
        {                                                                    
            Console.WriteLine("PDF Filename: " + pdfName);
            Console.WriteLine("Page Number: " + pageNumber + " of " + images.Count);

            tessnet2.Tesseract tessocr = new tessnet2.Tesseract();
            //TODO change folder to startup Path
            tessocr.Init(@"C:\Users\Matt Taylor\Documents\Visual Studio 2012\Projects\TessNet2\TessNet2\bin\Debug\tessdata", "eng", false);

            tessocr.GetThresholdedImage(bmp, System.Drawing.Rectangle.Empty).Save("c:\\temp\\" + Guid.NewGuid().ToString() + ".bmp");
            //Tessdata directory must be in the directory than this exe
            Console.WriteLine("Multithread version");

            ocr.DoOCRMultiThred(bmp, "eng");
            //Console.WriteLine("Normal version");
            //ocr.DoOCRNormal(bmp, "eng");    
            //bmp.UnlockBits(bmp);
            bmp.Dispose();

            pageNumber++;
        }
    } 
}

Eventually once I try to run the code a few times after this error occurs, it will start throwing the error at the using (Bitmap bmp = image.ToBitmap()) line.

If I wait about 5 or 10 minutes, both of these errors go away.

Answer 1

As a first step I would wrap the tessnet code in a using statement

using(tessnet2.Tesseract tessocr = new tessnet2.Tesseract())
{
   tessocr.Init(...);
}

You also don't need to call bmp.Dispose() since that is also in a using statement.