magick input.png \
\( -clone 0 -gravity north -crop 100%x25%+0+0 -flip \) -reverse -append base.png

magick base.png -auto-orient \
-set option:wd "%[fx:w]" -set option:ht "%[fx:0.75*h]" -set option:center "%[fx:w/2],%[fx:h]" \
\( -clone 0 -fill black -colorize 100 -fill white \
-draw "translate %[center] rectangle -%[wd],-%[ht] %[wd],0" \
-resize 50% -blur 0x200 -resize 200% \) \
-compose multiply -composite output.png

magick -size 1600x3175 gradient: -rotate 0 -function polynomial 1,1,0.9,0,0,-0.5 gradient_mask.png

magick output.png gradient_mask.png -compose blur -set option:compose:args 30x20 -composite complate.png