Preview an Image Sequence with ImageMagick animate

You will finish with a repeatable way to view one image, a numbered set of images, or an existing animated file in an X display. You will also be able to slow the sequence down, limit its size, and distinguish an image problem from a missing display.

Allow about ten minutes for a first test. You need ImageMagick 6, readable image files, and access to an X server. This guide uses the installed imagemagick-6.q16 package, version 8:6.9.12.98+dfsg1-5.2ubuntu0.1~esm13, whose executable reports ImageMagick 6.9.12-98 Q16. The command is normally unprivileged. Do not use sudo to open somebody else's display or to work around a bad file path.

1. Check the installed command and display

Confirm which executable will run and whether the shell has an X display selected:

$ command -v animate-im6.q16
/usr/bin/animate-im6.q16
$ animate-im6.q16 -version
Version: ImageMagick 6.9.12-98 Q16 x86_64 18038 https://legacy.imagemagick.org
$ printf 'DISPLAY=%s\n' "$DISPLAY"
DISPLAY=:0

The exact version line can differ after a package update. The useful checks are that the executable exists and that DISPLAY names a reachable X server. The installed manpage calls the program animate-im6.q16; the local animate and animate-im6 manpages describe the same command. Use the fully qualified name in scripts so an ImageMagick 7 installation or a different wrapper does not silently change the behaviour.

2. Check the input without opening it

Use identify, a separate ImageMagick command, to check names, formats and dimensions before asking animate to open a window:

$ identify /path/to/frame-01.png /path/to/frame-02.png
/path/to/frame-01.png PNG 640x480 640x480+0+0 8-bit sRGB 2c 163B 0.000u 0:00.000
/path/to/frame-02.png PNG 640x480 640x480+0+0 8-bit sRGB 2c 163B 0.000u 0:00.000

Your metadata will differ. Check that each path is readable, the format is recognised, and the dimensions are what you expect. This is a useful separation of concerns: identify can prove that the files are image files, while animate needs an X server to display them.

If the files are numbered frames, let the shell expand them in the order you intend:

$ printf '%s\n' /path/to/frames/frame-*.png
/path/to/frames/frame-01.png
/path/to/frames/frame-02.png
/path/to/frames/frame-03.png

Do not assume that a wildcard sorts numerically. Names such as frame-1.png and frame-10.png can put frame 10 before frame 2. Rename or explicitly list files when order matters. Keep the original frames: animate displays them and does not need to rewrite them.

3. Open one image or an existing animation

Start with one known-good image. The command stays attached to the display until you close its window or interrupt it:

$ animate-im6.q16 /path/to/preview.png

For an animated GIF, pass the GIF as one input. Its image sequence and saved animation settings are read as input:

$ animate-im6.q16 /path/to/example.gif

To animate separate frames, pass all of them in order:

$ animate-im6.q16 /path/to/frames/frame-01.png /path/to/frames/frame-02.png /path/to/frames/frame-03.png

When a window appears, click it to expose the ImageMagick command widget. The installed manual documents button 1 as the control that maps or unmaps that widget. If the command immediately reports that it cannot open the X server, return to step 1. If it opens but fails on one frame, run identify on each input and test the frames individually.

4. Set a useful playback speed

The -delay image setting is measured in centiseconds. For a tenth of a second per frame, use 10:

$ animate-im6.q16 -delay 10 /path/to/frames/frame-*.png

A larger value is slower. For example, -delay 50 requests half a second. This is a request applied while the sequence is read, not a change to the source files. If a GIF already carries frame delays, an explicit command-line setting is a useful test when the stored timing is too quick to inspect.

The -loop setting controls how many times the images loop before the command exits. Combine it with a deliberately short test sequence when you need a bounded run:

$ animate-im6.q16 -delay 25 -loop 2 /path/to/frames/frame-01.png /path/to/frames/frame-02.png

Do not use an unbounded display command in an unattended job and expect it to finish. A graphical animation is an interactive viewer, not a video encoder or a service. Press the terminal interrupt key, normally Ctrl-C, if you need to stop the foreground process. Closing the window is also a normal way to end an interactive preview.

5. Fit large images to the window

Use -resize when the source images are too large for the display. The geometry 1200x800> means reduce images that exceed either bound while preserving their aspect ratio:

$ animate-im6.q16 -resize '1200x800>' /path/to/frames/frame-*.png

The quotes protect the geometry from shell metacharacter handling. The greater-than sign is part of ImageMagick's geometry syntax, so it is written as > in this article's HTML but appears as > when copied from the code block. This operation affects the displayed image sequence, not the files on disk.

If you need a fixed window position or preferred size, -geometry sets the Image window geometry. It is separate from -resize: the former concerns the X window, while the latter changes the image presented to it.

6. Diagnose the common failures

Unable to open X server: check DISPLAY, the session you are logged into, and whether your connection has X authorisation. This is not an image-format error. On a headless machine, use identify or another non-graphical workflow instead of trying random display values.

Unable to open image: inspect the exact path and permissions:

$ ls -l /path/to/preview.png
$ test -r /path/to/preview.png && echo readable
readable

The order looks wrong: print the shell-expanded arguments, then use zero-padded names or an explicit list. The sequence is too fast: add a larger -delay. One frame is corrupt: find it with identify and remove it from the preview list, rather than modifying the source archive.

Do not treat -authenticate or -decipher as ordinary viewing options for untrusted files. They involve protected image data and a password or cipher file. Keep secrets out of shell history and process listings, and only use those options when you have verified the input and the key material.