cjxl -d 1.0 has heavy banding in some cases and is far from visually lossless
On some images, -d 1.0 is far from visually lossless, as banding becomes apparent until using a significantly smaller distance (~0.3). I suspect this is due to dithering in the original image giving a nice smooth transition by emulating higher depth well, but this is lost when the image is lossily compressed with cjxl. See the lossless attached file for an example, particularly in the lower left and lower right corners after compressing it with cjxl.
Operating System: Linux 5.10.7-3-MANJARO #1 SMP PREEMPT Fri Jan 15 21:11:34 UTC 2021 x86_64
JPEG XL software version:
cjxl [v0.2.0 | SIMD supported: AVX2,SSE4,Scalar]
Compilation: Don't recall exactly, but I followed your instructions.
CPU / architecture / device:
vendor_id : AuthenticAMD cpu family : 23 model : 1 model name : AMD Ryzen 7 1700 Eight-Core Processor stepping : 1 microcode : 0x8001138