img: https://i.imgur.com/hI1LD3b.jpg
3Dtext: http://www.fmwconcepts.com/imagemagick/3Dtext/index.php#t_zoomrotatetext
concave.sh
./3Dtext -t "HeMisC-neo" -f Open-Sans-SemiBold -p 72 -d northwest -x '#aeb1b9' -a 40 01.jpg;
./concave.sh 01.jpg #output a2.jpg
From 3Dtext -c font color, -p font-size, -d extrude direction, -x shadow color, -a extrude amount.
.
convert -fuzz 20% -transparent white 01.jpg 02.png for white to alpha.
Or edit the concave.sh outfile=filename_png;bc=none, to use on existing png. The script was extracted from fred's TEXTEFFECT
./3Dtext -t "SHORTER" ... -c red 03.jpg
For shorter words it's more obvious the concave effect is not centered. Quick solution is to break apart the words into 2 parts with different length of shadow, -a. Then use gimp to reassemble.
./3Dtext -t "NETF" ... -a 40 05.jpg;
./3Dtext -t "LIX" ... -a 30 06.jpg;
convert -fuzz 20% -transparent white 06.jpg 06.png
#after gimp
./concave.sh 07.jpg
montage -background lightgray @list -geometry +3+5 -tile 2x -gravity center -extent 462x156 x.jpg