A reliable workflow
Separate texture seams from import seams
A seam visible only after import often points to tangents, UV splits, compression, or mipmaps; a seam in the 2D repeat already exists in the texture.
Read blocks and bands as source evidence
Block patterns and ringing usually come from lossy compression, while stepped smooth gradients suggest low-precision source data or banding.
Keep vectors away from the tangent plane
Over-strong vectors approach the tangent plane and produce harsh, unstable shading; reduce strength or restore a larger Z level.
Start by locating where the artifact appears
Normal map artifacts are easier to diagnose when the pipeline is divided into stages. If a seam appears in a 2D repeated view, the pixels at opposite edges or UV borders already disagree. If it appears only on the mesh, inspect UV splits, mirrored islands, tangent generation, smoothing boundaries, and importer settings. If it appears only at distance, examine mipmaps and compression. Change one stage at a time and keep a known-good lossless file. This prevents a texture edit from hiding a mesh problem while creating new normal map artifacts elsewhere.
Read the visual signature of damaged data
Square blocks and ringing around edges usually indicate lossy compression. Stair steps across a smooth slope suggest an 8-bit or otherwise low-precision height source. Speckle and glitter often come from sensor noise, sharpened albedo, or vectors pushed too close to the tangent plane. Broad dents that follow photographic shadows indicate that lighting was interpreted as depth. These normal map artifacts call for different fixes: return to lossless data, improve source precision, apply limited pre-filtering, reduce strength, or rebuild height without baked illumination.
Test axis and color-space errors directly
When grooves look raised from one lighting direction, make a single green-flipped candidate and compare it under a vertically moving light. When both axes shade incorrectly, confirm the texture is read as non-color vector data and that red has not been inverted accidentally. Gamma decoding bends channel values away from their intended signed components; arbitrary RGB contrast also destroys vector length. A conversion tool should decode, change the requested axis, reconstruct when appropriate, and renormalize. Those controlled operations address normal map artifacts without treating a vector texture as a photograph.
Approve the fix in the production context
After correcting normal map artifacts, inspect the production mesh at its real UV scale, camera range, material strength, renderer, and platform quality. Rotate light across both axes and look at grazing angles, distant mip levels, mirrored geometry, and tile boundaries. Compare against the original failure so the improvement is measurable rather than merely different. Record convention, source, filter, strength, tangent assumptions, and importer overrides with the asset. A reproducible fix is more valuable than a one-off thumbnail that happens to look smooth.