Custom DPI when using Convert PDF to image

[vu205]

Can you add button to change dpi when convert to image ?

[xop01]

The Convert PDF to image command has no DPI control. It always renders at 150 DPI.

For a different DPI, use the command line tool. resolution is pixels per inch:

sumatrapdf-tool convert -o page%d.png -O resolution=300 file.pdf

%d becomes the page number. This does the same thing:

sumatrapdf-tool draw -o page%d.png -r 300 file.pdf

@vu205

[GitHubRulesOK]

Hmmm there are NO DPI inside a PDF and PNG will always say 96 per inch unless forced to show as non standard, (NOTE MuPDF use ODD standards) as that's the value used as a basic default. save the image above and there ARE no DPI it is X pixels by Y pixels but Paint will often show 96 or 120 depending on version.

THUS there WILL be scaling issue unless YOU decide what is your preference during conversions when using custom selections.

As suggested above and as shown before the best way to set YOUR OWN values is via command lines. but that is NOT setting DPI as there are no DPI to be set if you have an area that is PDF at DEFAULT SCALE of 72 units per inch (1:1 in nominal points) and you want those 72 units to be 300 printed pixels per 72 points then export at that re-solution density (THESES ARE NOT DPI as the DPI WILL STILL BE 96 for a PNG/web image)

NOTE the word DPI is in effect meaningless untill it is on PAPER. so using the above example we see the image is exported as IF it were 150 pixels per inch

set your r value to what you wish and other apps will use that

THE MuPDF default for DRAW is 72 not 96 nor 120 nor 150 nor 75 nor 600 nor 4800 the user decides. their desired over-ride.

>Each page in a PDF has a given width / height.
When converting to an image (like PNG), you can change the size of the output image:
sumatrapdf-tool draw -o "foo-%d.png" -w 400 -h 800 foo.pdf

>Render at a specific resolution (DPI) #
Instead of a pixel size, you can render at a resolution with -r (the default is 72 DPI). This is handy for print-quality images:
sumatrapdf-tool draw -o "foo-%d.png" -r 300 foo.pdf

[kjk]

Added in b67c84cff

Convert PDF to Images now has a Resolution (DPI) box: pick 72, 96, 150 (default), 300, 600 or 1200, or type any other value. Save Selection As Image got the same box.

It will be in the next pre-release build.

[vu205]

Thanks

[kjk]

In current SumatraPDF 3.7 pre-release builds, there are UI options for this and a script for the saved PDF.

Using the UI

Press Ctrl+K → Convert PDF to Images... (also right-click → Document). Choose PNG/JPEG/BMP, the destination template and Current/All/Range pages. The regular conversion dialog uses 150 DPI; use the script for a chosen DPI.

Using Run PDF Script

1. Open the input PDF. Save any unsaved annotations first (Ctrl+Shift+S).
2. Press Ctrl+K and choose Run PDF Script.... Paste the code below into the editor.
3. Keep Arg 1 as the input PDF, or replace it with the saved copy you want to process. Set the remaining arguments as follows; use Add argument for extra rows. Enter the values without surrounding quotes.

Argument	Meaning	Example value
Arg 1	Input PDF	input.pdf
Arg 2	image filename template (.png or .jpg; folder must exist)	C:\Exports\page-[page].png
Arg 3	DPI (default 300)	300
Arg 4	page range (default all)	1-3
Arg 5	JPEG quality (default 90)	90

4. Press Run Script. The output area reports the files written. Open the result to inspect it.

[page] or inserts the page number. Without one, the script adds a page-number suffix. Existing exports are overwritten.

From the command line

Save the code below as discussion-6283-render-images.js. In a command prompt opened in that folder, run:

sumatrapdf-tool.exe run "discussion-6283-render-images.js" "input.pdf" "C:\Exports\page-[page].png" "300" "1-3" "90"

Replace the example paths/values with yours. Use the full path to sumatrapdf-tool.exe if it is not on PATH. The arguments after the script filename correspond to Arg 1, Arg 2, etc. in the dialog.

// Discussion #6283: https://github.com/sumatrapdfreader/sumatrapdf/discussions/6283
// Info: Export pages as PNG or JPEG images at a chosen DPI.
// Arg: <INPUT> : Input PDF
// Arg: <DIR>/<BASE>-[page].png : Image filename template (.png or .jpg; folder must exist)
// Arg: 300 : DPI
// Arg: all : Page range
// Arg: 90 : JPEG quality
// Page range: all or empty = all pages; 2 = page 2; 4-6 = inclusive; 6-4 = reverse; 4- = through last; N = last; 2-N, N-1.
// Combine with commas: 2,4-6. Pages start at 1 and must exist; order kept, duplicates ignored; all/N ignore case; spaces around pages/separators allowed.

var input = scriptArgs[0];
var output = scriptArgs[1];
if (!input || !output) throw new Error("Supply input PDF and output path.");
function pathKey(s) {
  return s.replace(/\\/g, "/").toLowerCase();
}
if (pathKey(input) === pathKey(output)) throw new Error("Choose a different output path.");
var doc = Document.openDocument(input);
if (doc.needsPassword()) throw new Error("Use a decrypted input PDF.");
function save() {
  doc.save(output, "garbage=4,compress");
  print("Saved " + output);
}
function number(s, fallback) {
  var n = s === undefined || s === "" ? fallback : Number(s);
  if (!isFinite(n)) throw new Error("Invalid number: " + s);
  return n;
}
function pageList(text, count) {
  var pages = [];
  if (!text || /^all$/i.test(text)) {
    for (var i = 0; i < count; i++) pages.push(i);
    return pages;
  }

  var ranges = text.split(",");
  for (var i = 0; i < ranges.length; i++) {
    var range = ranges[i];
    var match = /^\s*(\d+|N)\s*(?:-\s*(\d+|N)?\s*)?$/i.exec(range);
    if (!match) throw new Error("Invalid page range: " + range);

    var first = /^N$/i.test(match[1]) ? count : Number(match[1]);
    var last = first;
    if (match[2]) last = /^N$/i.test(match[2]) ? count : Number(match[2]);
    else if (range.indexOf("-") >= 0) last = count;
    if (first < 1 || last < 1 || first > count || last > count) {
      throw new Error("Page outside document: " + range);
    }

    var step = first <= last ? 1 : -1;
    for (var page = first; ; page += step) {
      if (pages.indexOf(page - 1) < 0) pages.push(page - 1);
      if (page === last) break;
    }
  }
  return pages;
}
var kPointsPerInch = 72;
var dpi = number(scriptArgs[2], 300);
var pageRange = scriptArgs[3];
var selected = pageList(pageRange, doc.countPages());
var quality = number(scriptArgs[4], 90);
if (dpi <= 0 || dpi % 1) throw new Error("DPI must be a positive integer.");
if (quality < 1 || quality > 100) throw new Error("JPEG quality must be 1..100.");
var ext = /\.(png|jpe?g)$/i.exec(output);
if (!ext) throw new Error("Output template must end in .png or .jpg.");
var template = output;
if (!/\[page\]|<N>/.test(template)) template = template.replace(/(\.[^.]+)$/, "-[page]$1");
for (var i = 0; i < selected.length; i++) {
  var p = selected[i];
  var n = ("000" + (p + 1)).slice(-Math.max(3, String(p + 1).length));
  var path = template.replace(/\[page\]|<N>/g, n);
  var pix = doc
    .loadPage(p)
    .toPixmap(Matrix.scale(dpi / kPointsPerInch, dpi / kPointsPerInch), ColorSpace.DeviceRGB, false);
  pix.setResolution(dpi, dpi);
  if (ext[1].toLowerCase() === "png") pix.saveAsPNG(path);
  else pix.saveAsJPEG(path, quality);
  print("Saved " + path);
}