Find Ticks with Your Phone — How the Trick Works
In short: When your phone shows the camera image with inverted colours, a dark tick on lighter skin becomes a bright, almost glowing dot. What passes for dirt, a shadow or a freckle to the naked eye stands out at once in the inverted view — with your phone's built-in tools or straight away with TickSpot.
Why ticks are so easy to miss
According to the Robert Koch Institute, unfed nymphs are only about one to two millimetres across, adults about three to four. They are dark brown to black and prefer spots that are hard to see: the RKI names the hairline, ears, neck, armpits, the crook of the elbow, navel, genital area and back of the knee. Among freckles, on tanned skin or in hair, a dot that size is hard to tell from everything else. What ticks look like at every stage is shown in the drawings in "What do ticks look like?".
What colour inversion does
Inversion turns every colour value into its opposite: dark becomes light, skin pink becomes a cool blue-green. The difference in brightness between tick and skin stays just as large, but it flips — the tick is now the brightest spot in the image. A small bright speck on a dark background usually catches the eye at once; a small dark speck on warm skin easily disappears among pores, hairs and shadows.
How to do the check with TickSpot
- Open TickSpot and allow camera access — the inverted view starts straight away.
- Hold the camera about 10 to 20 centimetres above the skin and move it slowly over the typical spots.
- In poor light, switch on the app's light; zoom in on suspicious dots.
- See a bright dot? Freeze the frame and look at it calmly instead of searching with a shaky hand.
The images stay on your device — TickSpot processes the camera image in the browser and uploads nothing.
Without an app: using your phone's built-in tools
The trick doesn't strictly need TickSpot. Both major systems can invert the image themselves:
- Android: Settings → Accessibility → Colour and motion → Colour inversion, then open the camera. The inversion applies to the whole screen, so every other app too, until you switch it off.
- iPhone: in the Magnifier app, Apple lets you add the "Filter" control to apply a colour filter; there are also controls for the flashlight and for freezing the image.
Both work. The difference is getting there: with the built-in tools it goes through the settings, and on Android every app is recoloured afterwards. TickSpot opens directly in the inverted view, the same on iPhone and Android, with light, zoom and freeze in one place.
Where the trick reaches its limits
- Dark skin, dark fur: inversion amplifies an existing difference in brightness; it doesn't create one. Where tick and background are similarly dark, the inverted image has little contrast too. Extra light, zoom and slow, section-by-section checking help.
- Thick hair: the camera needs a clear strip of skin — the parting technique is in "Finding ticks in thick hair".
- Unclear dots: not every bright dot is a tick. How to tell a tick from a mole is in "Tick or Mole?"
- Hard-to-reach spots: back and back of the head are best checked by two people or with a frozen frame; the spots are in "Where do ticks attach?"
Try it right now: TickSpot runs free in your browser — no sign-up, and all images stay on your phone.
Start the tick checkFrequently asked questions
Why are ticks easier to see with inverted colours?
Because the contrast flips: light skin turns dark and a dark tick turns bright. A small bright dot on a dark background usually stands out at once, while a dark dot on skin is easily taken for a shadow, dirt or a mole.
Does it work without an app?
Yes. On Android, colour inversion for the whole screen is under Settings, Accessibility, Colour and motion. On the iPhone, a colour filter can be added as a control in the Magnifier app. Both work but take a few steps through the settings.
Does the trick work on dark skin or dark fur?
Only partly. Inversion amplifies an existing difference in brightness; it doesn't create one. Where tick and background are similarly dark, the inverted image has little contrast too. Extra light, zoom and slow, section-by-section checking help.
Does the phone replace checking with your eyes?
No, it makes checking easier. The check is still needed and must cover the typical spots — the Robert Koch Institute names the hairline, ears, armpits, navel, genital area and back of the knee, among others.
Sources
- Robert Koch Institute: Tick FAQ (size of the life stages, preferred bite sites — in German)
- Google: Change text and display settings (colour inversion on Android)
- Apple: Customise Magnifier controls on iPhone (filter, flashlight, freeze)
Note: TickSpot is a tool for making ticks visible and does not replace medical advice. After a tick bite, with skin changes or if unsure, seek medical advice.