ImageMagick

Contents

Sources

NOTE: mitigation of the following error

convert-im6.q16: attempt to perform an operation not allowed by the security policy `PDF' @ error/constitute.c/IsCoderAuthorized/408.
convert-im6.q16: no images defined `image.jpeg' @ error/convert.c/ConvertImageCommand/3258.

Inside file /etc/ImageMagick-6/policy.xml
Add the following line <policy domain="coder" rights="read|write" pattern="PDF" />

File info

identify -verbose <file>

Naming

Naming

convert source.pdf destination.png → destination-0.png, destination-1.png,...
convert source.pdf destination%d.png → destination1.png, destination2.png,...
convert source.pdf destination%03d.png → destination-000.png, destination-001.png,...

Pages restriction

convert source.pdf[1] destination.png → destination.png which is the 2^nd page (0 based)
convert source.pdf[1-3] destination.png → destination-1.png, destination-2.png, destination-3.png
convert source.pdf[1,3] destination.png → destination-1.png, destination-3.png

Quality, density and scale

Quality → compression level
quality documentation
JPEG/MIFF/PNG compression level between 1 (bad quality) and 100 (high quality). Default value (92), 90 or 95 are good values.
convert -quality 92 source.pdf[1] destination.jpeg

Density → pixels per inch
density documentation
Without changing the size of the image, the density changes the number of pixels per inch. Higher density means higher number of pixels for the image. This option is useful to increase text readability. 72 (or 72x72) is the default.
convert -density 72 source.pdf[1] destination.jpeg

Resize → ...
resize documentation
convert large-square.jpeg -resize 150x150 small-square.jpeg

Scale → ...
scale documentation
convert -scale

Sample → ...
sample documentation
convert -sample resize which does NOT create new color. More compact even if less beautiful.

Format conversion

convert source.png destination.jpeg

PNG background : remove alpha and replace with white
convert raw-footage.png -background white -alpha remove -flatten -alpha off test1.jpeg

Border

convert source.jpeg -bordercolor white -border 50x30 destination.jpeg

50 = right and left border
30 = top and bottom border

Turn transparency into white (NOT black!)

flatten documentation
Use -flatten parameter: convert source.pdf -flatten destination.jpeg

90° rotation

rotate documentation
convert -rotate 90 source.jpeg destination.jpeg

Crop file

crop documentation

convert source.jpeg -crop 1380x1017+150+0 destination.png
convert source.jpeg -crop '50%x100%+0%+0%' destination.png
convert source.jpeg -crop '50%x100%+595%' destination.jpg

Text printing on image file

convert -size 300x12 -pointsize 9 label:"helloworld" fichier.png

Image composition (one on top of the other)

composite -compose Over -gravity NorthEast top.png bottom.jpeg result.jpeg

Backlinks: Command line:pdf