plot_alignment channel name rendering

[scott-huberty]

When I run mne.viz.plot_alignment(..., show_channel_names=True), the channel names text labels are difficult to read as compared to the online tutorial:

# From the MNE-Python root with your environment activated
ipython -i examples/visualization/eeg_on_scalp.py

The show_channel_names parameter was added in #13570 , cc @aman-coder03

I am using an Intel Mac:

mne.sys_info output

Platform             macOS-14.6.1-x86_64-i386-64bit
Python               3.11.14 | packaged by conda-forge | (main, Oct 22 2025, 22:53:07) [Clang 19.1.7 ]
Executable           /Users/scotterik/miniforge3/envs/mnedev_311/bin/python3.11
CPU                  Intel(R) Core(TM) i5-1038NG7 CPU @ 2.00GHz
machdep.cpu.family: 6
machdep.cpu.model: 126
machdep.cpu.extmodel: 7
machdep.cpu.extfamily: 0
machdep.cpu.stepping: 5
machdep.cpu.feature_bits: 9221959987971750911
machdep.cpu.leaf7_feature_bits: 4072613871 1077960526
machdep.cpu.leaf7_feature_bits_edx: 3154118160
machdep.cpu.extfeature_bits: 1241984796928
machdep.cpu.signature: 460517
machdep.cpu.brand: 0
machdep.cpu.features: FPU VME DE PSE TSC MSR PAE MCE CX8 APIC SEP MTRR PGE MCA CMOV PAT PSE36 CLFSH DS ACPI MMX FXSR SSE SSE2 SS HTT TM PBE SSE3 PCLMULQDQ DTES64 MON DSCPL VMX EST TM2 SSSE3 FMA CX16 TPR PDCM SSE4.1 SSE4.2 x2APIC MOVBE POPCNT AES PCID XSAVE OSXSAVE SEGLIM64 TSCTMR AVX1.0 RDRAND F16C
machdep.cpu.leaf7_features: RDWRFSGS TSC_THREAD_OFFSET SGX BMI1 AVX2 FDPEO SMEP BMI2 ERMS INVPCID FPU_CSDS AVX512F AVX512DQ RDSEED ADX SMAP AVX512IFMA CLFSOPT IPT AVX512CD SHA AVX512BW AVX512VL AVX512VBMI UMIP PKU GFNI VAES VPCLMULQDQ AVX512VNNI AVX512BITALG AVX512VPOPCNTDQ RDPID SGXLC FSREPMOV MDCLEAR IBRS STIBP L1DF ACAPMSR SSBD
machdep.cpu.extfeatures: SYSCALL XD 1GBPAGE EM64T LAHF LZCNT PREFETCHW RDTSCP TSCI
machdep.cpu.logical_per_package: 16
machdep.cpu.cores_per_package: 8
machdep.cpu.microcode_version: 198
machdep.cpu.processor_flag: 7
machdep.cpu.core_count: 4
machdep.cpu.thread_count: 8 (8 cores)
Memory               32.0 GiB

Core
├☒ mne               1.11.0.dev199+g6589b8672.d20260219 (outdated, release 1.11.0 is available!)
├☑ numpy             2.4.1 (OpenBLAS 0.3.30 with 8 threads)
├☑ scipy             1.17.0
└☑ matplotlib        3.10.8 (backend=qtagg)

Numerical (optional)
├☑ sklearn           1.8.0
├☑ nibabel           5.3.2
├☑ nilearn           0.13.1
├☑ dipy              1.11.0
├☑ pandas            2.3.3
├☑ h5io              0.2.5
├☑ h5py              3.15.1
└☐ unavailable       numba, openmeeg, cupy

Visualization (optional)
├☑ pyvista           0.46.5 (OpenGL 4.1 INTEL-22.5.11 via Intel(R) Iris(TM) Plus Graphics OpenGL Engine)
├☑ pyvistaqt         0.11.3
objc[90352]: Class QT_ROOT_LEVEL_POOL__THESE_OBJECTS_WILL_BE_RELEASED_WHEN_QAPP_GOES_OUT_OF_SCOPE is implemented in both /Users/scotterik/miniforge3/envs/mnedev_311/lib/libQt5Core.5.15.15.dylib (0x1617543d0) and /Users/scotterik/miniforge3/envs/mnedev_311/lib/libQt6Core.6.10.2.dylib (0x18d3325b0). One of the two will be used. Which one is undefined.
objc[90352]: Class KeyValueObserver is implemented in both /Users/scotterik/miniforge3/envs/mnedev_311/lib/libQt5Core.5.15.15.dylib (0x1617543f8) and /Users/scotterik/miniforge3/envs/mnedev_311/lib/libQt6Core.6.10.2.dylib (0x18d3325d8). One of the two will be used. Which one is undefined.
objc[90352]: Class RunLoopModeTracker is implemented in both /Users/scotterik/miniforge3/envs/mnedev_311/lib/libQt5Core.5.15.15.dylib (0x161754448) and /Users/scotterik/miniforge3/envs/mnedev_311/lib/libQt6Core.6.10.2.dylib (0x18d332628). One of the two will be used. Which one is undefined.

[aman-coder03]

hey @scott-huberty, thanks for sharing the screenshot!
looks like the main issue is scale=0.005 is too large for the 3D scene... the labels end up huge and overlap each other badly. also the white text on the pale scalp surface doesn't help readability.
i will reduce the scale and switch to a darker text color and open a PR soon