How can I convert a scanned PDF to an image using MATLAB?

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How can I import a scanned PDF into MATLAB and convert it to image files?
I tried to use extractFileText() from Text Analytics Toolbox, but it only works for native PDFs and not scanned PDFs:
>> extractFileText('example.pdf')
ans =
<missing>

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 5 Jan 2021
MATLAB ships with the Apache PDFBox Java library which allows importing and rendering PDF files. Use the following MATLAB function PDFtoImg() to import a scanned PDF, and save each page as a separate PNG file:
function images = PDFtoImg(pdfFile)
import org.apache.pdfbox.*
import java.io.*
filename = fullfile(pwd,pdfFile);
jFile = File(filename);
document = pdmodel.PDDocument.load(jFile);
pdfRenderer = rendering.PDFRenderer(document);
count = document.getNumberOfPages();
images = [];
for ii = 1:count
    bim = pdfRenderer.renderImageWithDPI(ii-1, 300, rendering.ImageType.RGB);
    images = [images (filename + "-" +"Page" + ii + ".png")];
    tools.imageio.ImageIOUtil.writeImage(bim, filename + "-" +"Page" + ii + ".png", 300);
end
document.close()
Notes:
1. It is important to split the input PDF data into images for each PDF page. For example, if “example.pdf” contains 13 pages, then we should convert 13 pages to 13 images.
2. For subsequent OCR tasks, is important to render the PDF pages with 300 dpi or higher resolution:\n
>> bim = pdfRenderer.renderImageWithDPI(ii-1, 300, rendering.ImageType.RGB);
  14 Comments
Karolina Charaziak
Karolina Charaziak on 7 Apr 2022
Edited: Karolina Charaziak on 7 Apr 2022
For a change I keep getting this error:
Error using PDFtoImg Too many input arguments.
I am using script as posted on mathworkswebinar (weirdly it works when i run it as live script but i get an error when I just copy paste it to the command line)

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More Answers (1)

Zhongcheng Sun
Zhongcheng Sun on 15 May 2022
I am facing an error with line "pdmodel.PDDocument.load(jFile)", which is "Arguments must contain strings."
could you pls help solve this?

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