Exporting a Screenshot with a Transparent Background
Why a transparent export needs PNG rather than JPEG, the drop-shadow problem that ruins most composites, and where transparency is worth the file size.
Updated August 2026
Quick answer
Transparency requires PNG — JPEG has no alpha channel and fills the transparent area with white. The trap is the drop shadow: a shadow rendered against the old background exports as a grey halo that appears the moment you place the image somewhere else. ShotPost suppresses the shadow automatically on transparent export, so edges composite cleanly.
Why the format decides this
| Format | Transparency | Use for |
|---|---|---|
| PNG | Yes — full alpha channel | Anything composited onto another background |
| JPEG | No | Photographs where transparency is irrelevant and size matters |
| HEIC | Yes, but poorly supported | Not worth the compatibility risk for assets you hand off |
Exporting a transparent design as JPEG is the most common version of this mistake, and the result is a white rectangle rather than an error — so it usually survives until someone else places the file.
The drop-shadow problem
A drop shadow is drawn onto whatever sits behind the object. Remove the background but keep the shadow and the shadow's pixels stay — a soft grey fringe that was invisible against the original background and obvious against anything else.
It shows up as a dirty halo on a dark slide, or a faint rectangle where the shadow's own edge sat. Because it looks correct in the editor, it is normally discovered by the person placing the asset rather than the person who made it.
ShotPost handles this by suppressing the drop shadow automatically when the background is set to transparent — the case is detected rather than left as a setting to remember. Transparent projects are tagged so they stay identifiable in the gallery.
When transparency is worth it
- Slides and decks, where the deck's own background should show through
- Marketing pages where the mockup sits on a coloured or gradient section
- Press kits and hand-offs, where you cannot know the destination background
- Composites layering a device over other artwork
Where it is not worth it: App Store screenshots, which must be fully opaque — Apple rejects transparency outright. For those, set an actual background rather than exporting transparent and flattening later.
Transparent PNGs are also substantially larger than the equivalent JPEG, so for a web page whose background is a known flat colour, matching that colour in the export is often the better engineering choice.
Common questions
Why is my transparent background white?
Almost always because the export was JPEG, which has no alpha channel and fills transparency with white. Re-export as PNG. If it is already PNG, check the background is genuinely set to transparent rather than to a white fill.
What is the grey edge around my exported image?
A drop shadow that survived the background removal. It was invisible against the original background and shows against the new one. ShotPost suppresses the shadow automatically on transparent export.
Can I use a transparent PNG for App Store screenshots?
No. Apple requires opaque screenshots and rejects transparency. Set a real background — a solid colour or gradient — and export at the exact required dimensions.
How do I find my transparent projects later?
They are tagged as PNG in the gallery, and the filter chips include a transparent-background filter, so you can pull up just those projects without opening each one.
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