Differences

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--- doc:appunti:prog:pdf [2022/12/07 09:25] – [Dividere le pagine in due o più pagine] niccolo
+++ doc:appunti:prog:pdf [2026/04/03 16:25] (current) – [Rimuovere la password di un file PDF] niccolo
@@ Line 51: / Line 51: @@
 <code>
-convert -density 150 -quality 100 input.pdf output.jpg
+convert -units pixelsperinch -density 150 -quality 100 input.pdf output.jpg
 </code>
@@ Line 57: / Line 57: @@
 <code>
-convert -density 300 -background white -alpha remove -define png:color-type=6 input.pdf output.png
+convert -units pixelsperinch -density 300 \
+    -background white -alpha remove -define png:color-type=6 \
+    input.pdf output.png
 </code>
@@ Line 210: / Line 212: @@
 <code>
 rsvg-convert --format pdf --keep-aspect-ratio --output output.pdf page*.svgz
+</code>
+===== Rimuovere la password di un file PDF =====
+<code>
+pdftk doc-protected.pdf input_pw PROMPT output doc.pdf
+</code>
+Al posto di **PROMPT**, che chiede la password da stdinput, si può indicare la password direttamente sulla riga di comando.
+===== Ridurre la risoluzione delle immagini in un file PDF =====
+<code bash>
+#!/bin/sh
+# ~72 dpi, ~150 dpi, ~300 dpi
+#RESOLUTION='screen'
+RESOLUTION='ebook'
+#RESOLUTION='printer'
+INPUT="$1"
+if [ ! -f "$INPUT" ]; then
+    echo "Usage: $(basename "$0") [INPUT.PDF]"
+    exit 1
+fi
+OUTPUT="$(echo $INPUT | sed 's/.pdf/.reduced.pdf/')"
+if [ -f "$OUTPUT" ]; then
+    echo "ERROR: Output file already exists: $OUTPUT"
+    exit 1
+fi
+gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/"$RESOLUTION" \
+   -dNOPAUSE -dQUIET -dBATCH \
+   -sOutputFile="$OUTPUT" "$INPUT"
 </code>