Workaround for 'magick display' on Mac

Question

I have installed imagemagick @7 using 'brew' on a Big Sur Mac. The 'display' option gives an error "display: delegate library support not built-in (X11)".

This is not a mystery. The solution used to be to install imagemagick with some -with-X11 option. This option has gone from the latest 'brew' builds. It may be back someday, but I understand the X11 support was problematic. If this is so, then building from source sounds tricky.

I can convert my weird format files to another format, and open them in some compatible viewer. I want to look at floating-point files without worrying that the values may have been clipped by format conversion. I might use python matplotlib. But is there a neater way?

Following from the comments, I installed 'xquartz' and built ImageMagick 7.0.10 from source. My current version was done with ./configure --with-modules (this is probably not needed for what I wanted). The configure reports showed that the X11 libraries were found and linked. 'make check' passed. The environment variable DISPLAY is set to :0. But if I try to display an image with (for example)...

magick display logo.gif ...I get... display: unable to open X server `:0' @ error/display.c/DisplayImageCommand/412.

This is progress: it is trying to connect but isn't managing it. I find lots of possible solutions from about 2018, but nothing on version 7 (which I need) on Big Sur.

ImageMagic display now works for me. I rebooted the Mac (may not have been necessary but someone advised this). I deleted the export DISPLAY=":0" - this was a relic from earlier experiments. I run Xquartz, which sets up the Display to something long and complicated, and as long as XQuartz is running, commands work from any terminal. Thanks, everyone.

Answer 1

Recent versions of homebrew have dropped support for X11 using the --with-X11 option to ImageMagick. That means you cannot readily use commands like the following that display an image directly without having to save it to disk and open some non-ImageMagick viewer:

magick -size 640x480 xc:red display:

However, you can use macOS's built-in Image Preview in a very analogous way, by adding your own "delegate". Just create a file with these contents:

<delegate decode="png" encode="display" spawn="True" command="magick %i %u.png && /usr/bin/open -a Preview %u.png"/>

and save it as $HOME/.config/ImageMagick/delegates.xml That tells ImageMagick that when you put display: at the end of the command, it should take the current image, make a temporary PNG version of it and use the Preview app to display it.

Now, whenever you want to view the output of an ImageMagick command just use:

magick INPUTIMAGE ... processing ... display: