Issues in Pascal Context GT Visualization

[russellward2025]

Steps to Reproduce the Bug:

1. Full runnable code or changes made:
   Refer to the failed pull request: visualizer's sem_seg function dtype uint8 cannot handle classes more than 256! #5391

2. Exact command run:
   I executed tools/visualize_data and noticed that visualize.py in the utils folder uses an outdated numpy dtype.

3. Logs or relevant observations:
   The image should correspond to train(id: 359), but there is an overflow issue, referencing fly(id: 359-256 = 103) instead.

Expected Behavior:
It should handle classes greater than 256, but Pascal Context 459 results in an overflow.

Environment:

• Python 3.10
• NumPy 1.22.4
• PyTorch 1.13.1