Why does the picture change?
Not a video. One see-through PNG looks different before and after you open the image on X—because the background behind it changes.
1. UI background difference
On many light themes:
- Timeline: bright / near-white card background
- Expanded image: dark / near-black background
Near-transparent pixels let the background show through—so white “hides” some strokes and black “reveals” others.
Captions like “hold to reveal” are engagement copy; the real switch is open/lightbox background, not a special gesture API.
2. The formula (inverse alpha)
Display color ≈ pixel × α + background × (1 − α).
display = pixel × α + background × (1 − α)
If W is the white-bg look and B the black-bg look: α = clamp(1 − W + B), C = B / α.
α = clamp(1 − W + B) C = B / α
HoldReveal solves α and color per pixel from your A/B inputs (luma or RGB mode).
3. Why PNG-8
Large RGBA uploads can be recompressed on X. Indexed PNG-8 often keeps transparency more reliably.
4. Not those other trends
- HoldReveal: dual vision via transparency + white/black UI
- “Load in 4K” / “Tap the Post” grids: different mechanisms
5. Tips that work
- Match composition between A and B
- Strong contrast where the reveal should happen
- Post PNG from x.com on desktop
- Dark mode may spoil the timeline look
6. Steps in HoldReveal
- Upload A (white-bg look)
- Upload B (black-bg look)
- Preview white/black; tweak strength/mode
- Download PNG → post on X Web