Quick answer: Unity light cookie projecting full white instead of patterned light? Texture importer set to default 'Light Cookie' loses RGB - use 'Default' with Alpha From Grayscale instead.
Imported a black-and-white pattern PNG as light cookie. Light projects pure white onto walls.
Use Default type
Texture inspector > Texture Type = Default; Alpha Source = From Grayscale. Light reads alpha; alpha is now derived from luminance.
Or use Single Channel
For pure black/white cookies, Single Channel type is smallest. Bandwidth saved; functionality identical.
Verify cookie preview
Light component preview shows the cookie mask. White preview = lost data; patterned preview = correct.
“Texture import types are presets. Some presets do unhelpful things.”
If a Unity texture loses data, the import type is usually the cause. Switch to Default first; reapply specific settings as needed.