Convert PDF to Continous Jpg or Bitmap
Normally it is used to print to PDF, but it is fairly easy to define a new printer, change the output format to PNG (or JPG,...) and you get a numbered list of files (one per page of the original file).
I use it to create PNGs from PDFs which are protected regarding copy&paste. I then do OCR on the PNGs and still can access the text. Therefore I use a resolution of 600 dpi.
This is not completely what has been asked for (single jpg or bitmap) but once you have all the PNGs the rest is a question of finding a software that can join these into one big bitmap.
Stupid idea: Create a web-page of all the PNGs, open it in firefox and make a screenshot via Screengrab extension into one big file.
The crashing may be due to the huge size of the resulting bitmap. This way you have different steps to proceed and try (and not crash) each individually.
I have created PNGs from large PDFs so I think this wouldn't crash. I have no idea what Screengrab will behave like.
1. Split large PDF into multiple smaller PDFs.
You could use something like PDF Toolkit or PDF Split and Merge.
2. Convert all PDFs into images.
Perhaps you can use PDF-XChange Viewer?
3. Combine all images into one large image.
You could use the Panorama feature of IrfanView
If you're looking to automate this process, you could look into ImageMagick. Also, there are many free tools for PDF so it's possible you might find one program which can take care of all of this for you.
Here's a similar solution which avoids OCR:
For the longest time I had no idea what to do with the XPS printer, but last year I found a good reason for not deleting it which I thought I might share with you all.
It's a workaround for PDF restrictions which can be used as long as the PDF can be printed. Print the PDF to the XPS printer, open the resulting XPS file and then print back to a PDF file using a PDF printer. All of the restrictions of the original PDF document are lost in the conversion, but the text of the original PDF is left intact. I do this regularly when I run into problems trying to extract a few pages of a large PDF document with Adobe Acrobat. It would be nice if someone could automate the process and perhaps even make a batch conversion utility...