Problem
Dark gradient thumbnails develop crushed shadow blocks that hide subject separation.
Solution
Root Cause / Diagnostic:
Deep dark gradients with RGB values falling between 0 and 20 are aggressively compressed into flat, blocking black patches by YouTube's lossy video/image encoding. Any subtle subject separation relying on deep shadow detail is completely crushed and lost.
Actionable Fix:
1. Lift near-black shadow values using an Output Levels adjustment, raising the black floor from 0 to 18–25 on the luminance scale.
2. Add a strong colored rim light (e.g., cyan or warm amber) along the subject's dark edges to provide luminance separation from the dark background.
3. Check the image on a standard, uncalibrated TN or mobile LCD display to ensure dark subject borders remain clearly discernible.
Pro Tip:
Never let dark backgrounds fall below RGB 18; lifting the absolute black floor prevents YouTube's compression pipeline from crushing your subject into the background.
Deep dark gradients with RGB values falling between 0 and 20 are aggressively compressed into flat, blocking black patches by YouTube's lossy video/image encoding. Any subtle subject separation relying on deep shadow detail is completely crushed and lost.
Actionable Fix:
1. Lift near-black shadow values using an Output Levels adjustment, raising the black floor from 0 to 18–25 on the luminance scale.
2. Add a strong colored rim light (e.g., cyan or warm amber) along the subject's dark edges to provide luminance separation from the dark background.
3. Check the image on a standard, uncalibrated TN or mobile LCD display to ensure dark subject borders remain clearly discernible.
Pro Tip:
Never let dark backgrounds fall below RGB 18; lifting the absolute black floor prevents YouTube's compression pipeline from crushing your subject into the background.