Christmas projection mapping from your phone

1. 1

   Get Lazy Lighting. Download it from the App Store for iPhone and iPad, or Google Play for Android phones and tablets.

2. 2

   Connect your phone to the projector. A USB-C or Lightning to HDMI cable is the most reliable. iPhone and iPad can also use AirPlay, Android phones can use screen mirroring where the phone supports it, and Android TV or Google TV projectors connect wirelessly with Lazy Lighting Link.

3. 3

   Draw a shape on each surface. Add a Square, Circle, Outline or Text shape for each window, door or panel and drag its corners on your phone while you watch the projection line up. For an arched window, trace it with an Outline shape.

4. 4

   Pick a Christmas scene. Choose one of the 30 built-in Christmas scenes for each shape, or import your own videos and photos.

5. 5

   Lock it down and leave it running. Sandbag the tripod so nothing shifts, keep the phone plugged in, and on iPhone set Auto-Lock to Never so the phone doesn't sleep.

Yes. There is no special Christmas projector: any video projector with an HDMI input works, including the one you already own, a cheap mini projector or an old office projector. What matters is brightness for the surface (see the table below), not the label on the box.

The "Christmas projectors" sold in stores are mostly laser or snowflake light projectors. They spray the same moving dots or snowflakes over everything in front of them and can't fit a window, frame a door or play a scene like Santa's sleigh. Projection mapping uses a video projector and fits a separate animated scene to each window, door or section of the house.

Lazy Lighting's 30 Christmas scenes cover falling snow, Santa's sleigh, a twinkling light tree, a gingerbread parade, candy-cane stripes, knitted Christmas-sweater patterns with reindeer, snowmen, penguins and Santa, and wrapping-paper patterns of gifts, ornaments, bells, wreaths and snowflakes. Four of them are on the free plan; Pro unlocks the rest.

If you have bought Christmas window videos elsewhere, for example from AtmosFX, import the file and map it like a built-in scene. Your own videos and photos work the same way. Free Christmas loops from stock-video sites work too; our free videos guide lists where to find them and how to play them.

Brightness is the one thing you can't fix in the app. Rough guide, after dark:

Distance = throw ratio × picture width. Most home projectors, including both our picks, have a throw ratio of about 1.2, so the projector sits a little further back than the picture is wide. Check your projector's manual or spec sheet for its exact ratio; a short-throw model needs much less room.

The projector is the only real expense; your phone runs the show. A window or indoor display costs about $100–800: a compact projector (from about $70 for a mini LED model, a few hundred for a small laser one) plus a $15–50 HDMI adapter. A garage door or house front costs about $1,500–2,500, mostly for a projector with 4,000+ ANSI lumens, plus a stand or shelter and a long cable or wireless link. A used office projector can bring that down.

Lazy Lighting is free to download; the free plan includes four Christmas scenes with a small watermark, and Pro unlocks all 30.

Cold, damp nights are harder on a projector than on string lights. Most home projectors aren't sealed against rain, and many aren't rated to run below freezing, so check the operating temperature in your projector's manual before you plan a season outdoors.

• Project from somewhere sheltered. A covered porch, an open garage, a shed or a car parked on the driveway keeps rain and frost off the projector. Projecting from inside through a window works too: put the lens close to the glass and turn off the lights behind it, because the glass costs a little brightness and reflects anything lit in the room.
• If it has to sit outside, give it a roof, not a box. A plastic tub turned on its side, or a hood over the top, keeps rain off while leaving the vents open. Never seal a projector in a closed box: it needs airflow, and a closed box traps heat and moisture.
• Watch for condensation. Bringing a cold projector into a warm house can fog the lens and leave moisture inside. Let it warm up in its case or a closed bag for about an hour before you switch it on. Outside, dew on the lens blurs the image; a small hood helps, and a microfibre cloth clears it.
• Let the projector run the show, not your phone. Cold drains phone batteries, and a cable keeps your phone out by the projector. With Lazy Lighting Link on a Google TV or Android TV projector, your phone controls the show over Wi-Fi from indoors, and with Pro, Link Playback saves the show to the projector so you can put the phone away.
• Use outdoor-rated cords and a GFCI outlet. Indoor cords aren't made for wet ground or freezing nights. Keep plugs and adapters off the ground, in a weatherproof cord box if you have one.
• Check before you add a timer. A smart plug can switch the display off at night, but many projectors stay off when the power comes back. Look for a setting like auto power-on or direct power-on before you rely on a timer to switch it back on.
• Think about the neighbours. Keep the light off their windows and out of drivers' eyes, and switch the display off at a reasonable hour.

Lazy Lighting is for decorating. If you'd like a party game on the same wall, where everyone plays from their phone, our sister app WishPane makes games for a projector or TV.