Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:
wal -i "blackand white image file"

Expected behavior
A clear and concise description of what you expected to happen.
i expected to see a black and white pywal pallet

Screenshots/Logs
If applicable, add screenshots or logs to help explain your problem.
image: Using image yoru.png.
[I] colors: Generating a colorscheme.
[I] colors: Using wal backend.
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 16
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 17
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 18
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 19
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 20
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 21
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 22
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 23
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 24
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 25
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 26
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 27
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 28
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 29
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 30
[W] wal: Imagemagick couldn't generate a palette.
[W] wal: Trying a larger palette size 31
Traceback (most recent call last):
File "/usr/bin/wal", line 33, in
sys.exit(load_entry_point('pywal16==3.8.13', 'console_scripts', 'wal')())
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
File "/usr/lib/python3.14/site-packages/pywal/main.py", line 396, in main
parse_args(parser)
~~~~~~~~~~^^^^^^^^
File "/usr/lib/python3.14/site-packages/pywal/main.py", line 312, in parse_args
colors_plain = colors.get(
image_file,
...<4 lines>...
cst=args.contrast,
)
File "/usr/lib/python3.14/site-packages/pywal/colors.py", line 514, in get
colors = getattr(backend, "get")(img, light, c16=cols16)
File "/usr/lib/python3.14/site-packages/pywal/backends/wal.py", line 127, in get
return adjust(colors, light, c16=cols16)
File "/usr/lib/python3.14/site-packages/pywal/backends/wal.py", line 110, in adjust
return colors.generic_adjust(raw_colors, light, c16=cols16)
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.14/site-packages/pywal/colors.py", line 198, in generic_adjust
shade_16(colors, light, cols16)
~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.14/site-packages/pywal/colors.py", line 151, in shade_16
colors[k_v[15]] = util.lighten_color(colors[k_v[0]], 0.75)
~~~~~~^^^^^^^^^
IndexError: list assignment index out of range

Desktop (please complete the following information):

• OS: Arch
• Terminal: fish
• Version 4.4.0

Additional context
Add any other context about the problem here.
im assuiming htat because black and white photos are only black and white it cant diferetiate colors but id like to have black and white pywal themes for black and white wallpapers