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Convert PDF to image with high resolution

I'm trying to use the command line program convert to take a PDF into an image (JPEG or PNG). Here is one of the PDFs that I'm trying to convert.

I want the program to trim off the excess white-space and return a high enough quality image that the superscripts can be read with ease.

This is my current best attempt. As you can see, the trimming works fine, I just need to sharpen up the resolution quite a bit. This is the command I'm using:

convert -trim 24.pdf -resize 500% -quality 100 -sharpen 0x1.0 24-11.jpg

I've tried to make the following conscious decisions:

resize it larger (has no effect on the resolution)

make the quality as high as possible

use the -sharpen (I've tried a range of values)

Any suggestions please on getting the resolution of the image in the final PNG/JPEG higher would be greatly appreciated!

I don't know, you could also try link...
If you're on a mac, have a look at the man page for sips, the "scriptable image processing system". It's a command line image editor built in to macOS, works on PDFs and many other image types.
@ghoti sips will only convert the first page of a PDF file to an image.

J
JBWhitmore

It appears that the following works:

convert           \
   -verbose       \
   -density 150   \
   -trim          \
    test.pdf      \
   -quality 100   \
   -flatten       \
   -sharpen 0x1.0 \
    24-18.jpg

It results in the left image. Compare this to the result of my original command (the image on the right):

https://i.stack.imgur.com/qmLXI.jpg

(To really see and appreciate the differences between the two, right-click on each and select "Open Image in New Tab...".)

Also keep the following facts in mind:

The worse, blurry image on the right has a file size of 1.941.702 Bytes (1.85 MByte). Its resolution is 3060x3960 pixels, using 16-bit RGB color space.

The better, sharp image on the left has a file size of 337.879 Bytes (330 kByte). Its resolution is 758x996 pixels, using 8-bit Gray color space.

So, no need to resize; add the -density flag. The density value 150 is weird -- trying a range of values results in a worse looking image in both directions!


The density parameter is a bit special in that in must come before the input file. As PDF is a vector based file format which does not have (much) notion of pixels, it says something like "page is 8in by 12in". If you want pixel, you use the density setting to tell it, how many pixels per inch you want to get in the output. E. g. with 150 you would get 8x150=1200 by 12x150=1800 pixels in the resulting image. That's also the amount of pixels the sharpen, contrast, compression etc. settings work on.
It can result in black background on Mac OS (see stackoverflow.com/questions/10934456/…). To fix this, add -flatten.
i got a black background on Mac OS when I tried to convert pdf to png, adding -flatten solved it.
Wow! Just used the -density and -flatten option to reduce the size of a pdf (to another pdf). The -flatten option really helps a lot in reducing the total size. In my case, without visual disturbances.
The -density flag will likely give worse results on higher values if the quality of the starting image was lower than that.
m
majinnaibu

Personally I like this.

convert -density 300 -trim test.pdf -quality 100 test.jpg

It's a little over twice the file size, but it looks better to me.

-density 300 sets the dpi that the PDF is rendered at.

-trim removes any edge pixels that are the same color as the corner pixels.

-quality 100 sets the JPEG compression quality to the highest quality.

Things like -sharpen don't work well with text because they undo things your font rendering system did to make it more legible.

If you actually want it blown up use resize here and possibly a larger dpi value of something like targetDPI * scalingFactor That will render the PDF at the resolution/size you intend.

Descriptions of the parameters on imagemagick.org are here


It's twice the size mostly because the output density has been doubled and the jpg compression quality is set on max (so not much compression).
Using convert how will we know how many pages got converted?
Uh, this is definitely the way to go. Bump up that source density and remove the -sharpen. The quality is much much better than with the defaults and way more natural than with -sharpen.
This should be the best answer, not the current one. Also, this is needed as well on Ubuntu: mv /etc/ImageMagick-6/policy.xml /etc/ImageMagick-6/policy.xmlout when convert fails (source: askubuntu.com/a/1081907)
How to do this on windows without any third party tool or online connection? And with no admin rights on the PC.
N
Norman Ramsey

I use pdftoppm on the command line to get the initial image, typically with a resolution of 300dpi, so pdftoppm -r 300, then use convert to do the trimming and PNG conversion.


while not using Imagemagick, this solution seems most in the spirit of a transparent conversion. pdftoppm can also output JPEGs and PNGs.
pdftoppm resulted in really nice JPEGs for me (and still smaller than IM)! Thanks!
It seems that without the '-r' flag, pdftoppm uses the native resolution of the pdf, which is the maximal resolution you can get out of the pdf. The convert tool keeps this resolution.
PNG results are superior compared to JPG: pdftoppm -png -r 300 Or set the jpeg options with -jpegopt quality=100
G
Gabriel Staples

I really haven't had good success with convert [update May 2020: actually: it pretty much never works for me], but I've had EXCELLENT success with pdftoppm. Here's a couple examples of producing high-quality images from a PDF:

[Produces ~25 MB-sized files per pg] Output uncompressed .tif file format at 300 DPI into a folder called "images", with files being named pg-1.tif, pg-2.tif, pg-3.tif, etc: mkdir -p images && pdftoppm -tiff -r 300 mypdf.pdf images/pg [Produces ~1MB-sized files per pg] Output in .jpg format at 300 DPI: mkdir -p images && pdftoppm -jpeg -r 300 mypdf.pdf images/pg [Produces ~2MB-sized files per pg] Output in .jpg format at highest quality (least compression) and still at 300 DPI: mkdir -p images && pdftoppm -jpeg -jpegopt quality=100 -r 300 mypdf.pdf images/pg

For more explanations, options, and examples, see my full answer here:

https://askubuntu.com/questions/150100/extracting-embedded-images-from-a-pdf/1187844#1187844.

Related:

[How to turn a PDF into a searchable PDF w/pdf2searchablepdf] https://askubuntu.com/questions/473843/how-to-turn-a-pdf-into-a-text-searchable-pdf/1187881#1187881 Cross-linked: How to convert a PDF into JPG with command line in Linux? https://unix.stackexchange.com/questions/11835/pdf-to-jpg-without-quality-loss-gscan2pdf/585574#585574


V
Valerio

normally I extract the embedded image with 'pdfimages' at the native resolution, then use ImageMagick's convert to the needed format:

$ pdfimages -list fileName.pdf
$ pdfimages fileName.pdf fileName   # save in .ppm format
$ convert fileName-000.ppm fileName-000.png

this generate the best and smallest result file.

Note: For lossy JPG embedded images, you had to use -j:

$ pdfimages -j fileName.pdf fileName   # save in .jpg format

With recent "poppler-util" (0.50+, 2016) you can use -all that save lossy as jpg and lossless as png, so a simple:

$ pdfimages -all fileName.pdf fileName

extract always the best possible quality content from PDF.

On little provided Win platform you had to download a recent (0.68, 2018) 'poppler-util' binary from: http://blog.alivate.com.au/poppler-windows/


Just a minor correction: the second command in first code block should start with pdftoppm not with pdfimages
no, older pdfimages saves extracted images to ppm like pdftoppm, and pdftoppm never had the -list option. Current pdfimages can directly save to PNG and JPG with -all as stated in the note
to get poppler on Windows, msys2 is the best solution
take care that minimum MSYS2 installation is 400 MB, while blog.alivate.com.au/poppler-windows has an installer sized 7 MB
f
fmw42

In ImageMagick, you can do "supersampling". You specify a large density and then resize down as much as desired for the final output size. For example with your image:

convert -density 600 test.pdf -background white -flatten -resize 25% test.png

https://i.stack.imgur.com/4peJ6.png

Download the image to view at full resolution for comparison..

I do not recommend saving to JPG if you are expecting to do further processing.

If you want the output to be the same size as the input, then resize to the inverse of the ratio of your density to 72. For example, -density 288 and -resize 25%. 288=4*72 and 25%=1/4

The larger the density the better the resulting quality, but it will take longer to process.


C
Coder

I have found it both faster and more stable when batch-processing large PDFs into PNGs and JPGs to use the underlying gs (aka Ghostscript) command that convert uses.

You can see the command in the output of convert -verbose and there are a few more tweaks possible there (YMMV) that are difficult / impossible to access directly via convert.

However, it would be harder to do your trimming and sharpening using gs, so, as I said, YMMV!


b
bluish

It also gives you good results:

exec("convert -geometry 1600x1600 -density 200x200 -quality 100 test.pdf test_image.jpg");

V
Victoria Stuart

Linux user here: I tried the convert command-line utility (for PDF to PNG) and I was not happy with the results. I found this to be easier, with a better result:

extract the pdf page(s) with pdftk e.g.: pdftk file.pdf cat 3 output page3.pdf

e.g.: pdftk file.pdf cat 3 output page3.pdf

open (import) that pdf with GIMP important: change the import Resolution from 100 to 300 or 600 pixel/in

important: change the import Resolution from 100 to 300 or 600 pixel/in

in GIMP export as PNG (change file extension to .png)

Edit:

Added picture, as requested in the Comments. Convert command used:

convert -density 300 -trim struct2vec.pdf -quality 100 struct2vec.png

GIMP : imported at 300 dpi (px/in); exported as PNG compression level 3.

I have not used GIMP on the command line (re: my comment, below).

https://i.stack.imgur.com/1QaUN.png

https://i.stack.imgur.com/CwfMe.png


Can this be automated if you have thousands of pages?
@JBWhitmore: good question. Certainly it'd be simple to script the pdftk command, as it's already on the command line. I did a really quick Google search, and found that GIMP has a batch mode (I haven't tried it, but it looks like that should be scriptable as well): gimp.org/tutorials/Basic_Batch
@JBWhitmore an example script to automate this conversion is shown on this question/answer: unix.stackexchange.com/questions/121293/…
@tsherwen, If I read that link correctly it's how to automate the convert command. I'm not confused on how to do that. However, this answer says to use GIMP as one of the steps -- and neither this answer nor the linked appears to show how to automate that.
@JBWhitmore. I mistakenly was just thinking in terms of the question on convert. I only saw the part of this answer mentioning convert and your question whilst reading your automation comment. Thanks for your answer later on this thread, which I combined with the solution I linked to and solved a different issue I was having.
A
Armin Mustafa

One more suggestion is that you can use GIMP.

Just load the PDF file in GIMP->save as .xcf and then you can do whatever you want to the image.


The reason for doing this via the command line is that I had thousands of pages that needed this process.
Also, GIMP renders the page on loading, so you'll want to set the resolution when you select the pages to load. It doesn't much matter what you set the output parameters to if you start with the 100 DPI default on loading.
P
Pratap Singh Mehra

I have used pdf2image. A simple python library that works like charm.

First install poppler on non linux machine. You can just download the zip. Unzip in Program Files and add bin to Machine Path.

After that you can use pdf2image in python class like this:

from pdf2image import convert_from_path, convert_from_bytes
images_from_path = convert_from_path(
   inputfile,
   output_folder=outputpath,
   grayscale=True, fmt='jpeg')

I am not good with python but was able to make exe of it. Later you may use the exe with file input and output parameter. I have used it in C# and things are working fine.

Image quality is good. OCR works fine.


M
Mikhael Bolgov

PNG file you attached looks really blurred. In case if you need to use additional post-processing for each image you generated as PDF preview, you will decrease performance of your solution.

2JPEG can convert PDF file you attached to a nice sharpen JPG and crop empty margins in one call:

2jpeg.exe -src "C:\In\*.*" -dst "C:\Out" -oper Crop method:autocrop

The blurriness in the original PNG is what inspired the question in the first place, and the PNG in the accepted answer is rather crisp.
L
LF00

I use icepdf an open source java pdf engine. Check the office demo.

package image2pdf;

import org.icepdf.core.exceptions.PDFException;
import org.icepdf.core.exceptions.PDFSecurityException;
import org.icepdf.core.pobjects.Document;
import org.icepdf.core.pobjects.Page;
import org.icepdf.core.util.GraphicsRenderingHints;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

public class pdf2image {

   public static void main(String[] args) {

      Document document = new Document();
      try {
         document.setFile("C:\\Users\\Dell\\Desktop\\test.pdf");
      } catch (PDFException ex) {
         System.out.println("Error parsing PDF document " + ex);
      } catch (PDFSecurityException ex) {
         System.out.println("Error encryption not supported " + ex);
      } catch (FileNotFoundException ex) {
         System.out.println("Error file not found " + ex);
      } catch (IOException ex) {
         System.out.println("Error IOException " + ex);
      }

      // save page captures to file.
      float scale = 1.0f;
      float rotation = 0f;

      // Paint each pages content to an image and
      // write the image to file
      for (int i = 0; i < document.getNumberOfPages(); i++) {
         try {
         BufferedImage image = (BufferedImage) document.getPageImage(
             i, GraphicsRenderingHints.PRINT, Page.BOUNDARY_CROPBOX, rotation, scale);

         RenderedImage rendImage = image;
         try {
            System.out.println(" capturing page " + i);
            File file = new File("C:\\Users\\Dell\\Desktop\\test_imageCapture1_" + i + ".png");
            ImageIO.write(rendImage, "png", file);
         } catch (IOException e) {
            e.printStackTrace();
         }
         image.flush();
         }catch(Exception e){
             e.printStackTrace();
         }
      }

      // clean up resources
      document.dispose();
   }
}

I've also tried imagemagick and pdftoppm, both pdftoppm and icepdf has a high resolution than imagemagick.


P
Promise Preston

Please take note before down voting, this solution is for Gimp using a graphical interface, and not for ImageMagick using a command line, but it worked perfectly fine for me as an alternative, and that is why I found it needful to share here.

Follow these simple steps to extract images in any format from PDF documents

Download GIMP Image Manipulation Program Open the Program after installation Open the PDF document that you want to extract Images Select only the pages of the PDF document that you would want to extract images from. N/B: If you need only the cover images, select only the first page. Click open after selecting the pages that you want to extract images from Click on File menu when GIMP when the pages open Select Export as in the File menu Select your preferred file type by extension (say png) below the dialog box that pops up. Click on Export to export your image to your desired location. You can then check your file explorer for the exported image.

That's all.

I hope this helps


The question is for ImageMagick using a command line, not for Gimp using a graphical interface.
J
Jagveer Singh

get Image from Pdf in iOS Swift Best solution

func imageFromPdf(pdfUrl : URL,atIndex index : Int, closure:@escaping((UIImage)->Void)){
    
    autoreleasepool {
        
        // Instantiate a `CGPDFDocument` from the PDF file's URL.
        guard let document = PDFDocument(url: pdfUrl) else { return }
        
        // Get the first page of the PDF document.
        guard let page = document.page(at: index) else { return }
        
        // Fetch the page rect for the page we want to render.
        let pageRect = page.bounds(for: .mediaBox)
        
        let renderer = UIGraphicsImageRenderer(size: pageRect.size)
        let img = renderer.image { ctx in
            // Set and fill the background color.
            UIColor.white.set()
            ctx.fill(CGRect(x: 0, y: 0, width: pageRect.width, height: pageRect.height))
            
            // Translate the context so that we only draw the `cropRect`.
            ctx.cgContext.translateBy(x: -pageRect.origin.x, y: pageRect.size.height - pageRect.origin.y)
            
            // Flip the context vertically because the Core Graphics coordinate system starts from the bottom.
            ctx.cgContext.scaleBy(x: 1.0, y: -1.0)
            
            // Draw the PDF page.
            page.draw(with: .mediaBox, to: ctx.cgContext)
        }
        closure(img)

    }
    
    
}

//Usage

    let pdfUrl = URL(fileURLWithPath: "PDF URL")
    self.imageFromPdf2(pdfUrl: pdfUrl, atIndex: 0) { imageIS in
        
    }

The question is how to do it with ImageMagick's convert.
n
nsdb

this works for creating a single file from multiple PDF's and images files:

php exec('convert -density 300 -trim "/path/to/input_filename_1.png" "/path/to/input_filename_2.pdf" "/path/to/input_filename_3.png" -quality 100 "/path/to/output_filename_0.pdf"');

WHERE:

-density 300 = dpi

-trim = something about transparancy - makes edges look smooth, it seems

-quality 100 = quality vs compression (100 % quality)

-flatten ... for multi page, do not use "flatten"


p
pid

Use this commandline:

convert -geometry 3600x3600 -density 300x300 -quality 100 TEAM\ 4.pdf team4.png

This should correctly convert the file as you've asked for.


b
benwiggy

The following python script will work on any Mac (Snow Leopard and upward). It can be used on the command line with successive PDF files as arguments, or you can put in into a Run Shell Script action in Automator, and make a Service (Quick Action in Mojave).

You can set the resolution of the output image in the script.

The script and a Quick Action can be downloaded from github.

#!/usr/bin/python
# coding: utf-8

import os, sys
import Quartz as Quartz
from LaunchServices import (kUTTypeJPEG, kUTTypeTIFF, kUTTypePNG, kCFAllocatorDefault) 

resolution = 300.0 #dpi
scale = resolution/72.0

cs = Quartz.CGColorSpaceCreateWithName(Quartz.kCGColorSpaceSRGB)
whiteColor = Quartz.CGColorCreate(cs, (1, 1, 1, 1))
# Options: kCGImageAlphaNoneSkipLast (no trans), kCGImageAlphaPremultipliedLast 
transparency = Quartz.kCGImageAlphaNoneSkipLast

#Save image to file
def writeImage (image, url, type, options):
    destination = Quartz.CGImageDestinationCreateWithURL(url, type, 1, None)
    Quartz.CGImageDestinationAddImage(destination, image, options)
    Quartz.CGImageDestinationFinalize(destination)
    return

def getFilename(filepath):
    i=0
    newName = filepath
    while os.path.exists(newName):
        i += 1
        newName = filepath + " %02d"%i
    return newName

if __name__ == '__main__':

    for filename in sys.argv[1:]:
        pdf = Quartz.CGPDFDocumentCreateWithProvider(Quartz.CGDataProviderCreateWithFilename(filename))
        numPages = Quartz.CGPDFDocumentGetNumberOfPages(pdf)
        shortName = os.path.splitext(filename)[0]
        prefix = os.path.splitext(os.path.basename(filename))[0]
        folderName = getFilename(shortName)
        try:
            os.mkdir(folderName)
        except:
            print "Can't create directory '%s'"%(folderName)
            sys.exit()

        # For each page, create a file
        for i in range (1, numPages+1):
            page = Quartz.CGPDFDocumentGetPage(pdf, i)
            if page:
        #Get mediabox
                mediaBox = Quartz.CGPDFPageGetBoxRect(page, Quartz.kCGPDFMediaBox)
                x = Quartz.CGRectGetWidth(mediaBox)
                y = Quartz.CGRectGetHeight(mediaBox)
                x *= scale
                y *= scale
                r = Quartz.CGRectMake(0,0,x, y)
        # Create a Bitmap Context, draw a white background and add the PDF
                writeContext = Quartz.CGBitmapContextCreate(None, int(x), int(y), 8, 0, cs, transparency)
                Quartz.CGContextSaveGState (writeContext)
                Quartz.CGContextScaleCTM(writeContext, scale,scale)
                Quartz.CGContextSetFillColorWithColor(writeContext, whiteColor)
                Quartz.CGContextFillRect(writeContext, r)
                Quartz.CGContextDrawPDFPage(writeContext, page)
                Quartz.CGContextRestoreGState(writeContext)
        # Convert to an "Image"
                image = Quartz.CGBitmapContextCreateImage(writeContext) 
        # Create unique filename per page
                outFile = folderName +"/" + prefix + " %03d.png"%i
                url = Quartz.CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault, outFile, len(outFile), False)
        # kUTTypeJPEG, kUTTypeTIFF, kUTTypePNG
                type = kUTTypePNG
        # See the full range of image properties on Apple's developer pages.
                options = {
                    Quartz.kCGImagePropertyDPIHeight: resolution,
                    Quartz.kCGImagePropertyDPIWidth: resolution
                    }
                writeImage (image, url, type, options)
                del page

Presumably downvoted because python's been removed. Sadly, one can no longer rely on python3 and pyobjc being installed, so this whole method goes in the bin. It is possible to use Swift as a scripting language, but it's no fun.
S
Similar.Pictures

You can do it in LibreOffice Draw (which is usually preinstalled in Ubuntu):

Open PDF file in LibreOffice Draw. Scroll to the page you need. Make sure text/image elements are placed correctly. If not, you can adjust/edit them on the page. Top menu: File > Export... Select the image format you need in the bottom-right menu. I recommend PNG. Name your file and click Save. Options window will appear, so you can adjust resolution and size. Click OK, and you are done.


D
Dorian
convert -density 300 * airbnb.pdf

Looked perfect to me


a
akotian

It's actually pretty easy to do with Preview on a mac. All you have to do is open the file in Preview and save-as (or export) a png or jpeg but make sure that you use at least 300 dpi at the bottom of the window to get a high quality image.


Can this be automated if you have thousands of pages?

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