Issues in Pascal Context GT Visualization

Bug Report: Issues with Pascal Context GT Visualization

Steps to Reproduce the Bug:

Run the command tools/visualize_data.
Observe that visualize.py in the utils folder uses an outdated numpy dtype, leading to overflow issues.
Code and Changes:
Refer to the details in the failed pull request: #5391.

Observation:

The visualization incorrectly displays the image. For instance:
The class ID should be train (359) but overflows and maps to fly (103) due to the calculation 359 - 256 = 103.
Expected Behavior:
Handle more than 256 classes correctly without overflow.
(Note: Pascal Context contains 459 classes, causing the overflow issue.)

Environment:

Python: 3.10
Numpy: 1.22.4
PyTorch: 1.13.1
Additional Notes:
Simplify the reproduction steps to avoid dependencies on private datasets. Ensure the d type supports the required range of class IDs.

Start with tools/visualize_data and utils/visualize.py, then review failed PR #5391 and reproduce the overflow with a class ID above 255 without relying on private datasets. Done means visualization preserves class IDs through 459 and the reproduction validates the corrected dtype under the listed Python, NumPy, and PyTorch versions.

Written by the indexing model from the issue text.