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.