FLIR Camera Images: What Thermal Pictures Look Like
People search for “FLIR camera images” for one of three reasons: they want to see what thermal pictures look like before buying a camera, they want to identify a specific kind of problem (insulation gap, water leak, electrical fault) by comparing their own image to a reference, or they want to learn the basics of reading a thermal image. This guide covers all three angles. It explains the color palettes a FLIR camera offers, the image-fusion technology that overlays visible edges onto thermal scenes, what common household problems look like in infrared, and the limits of what a single image can prove.
What a FLIR camera image actually shows
A thermal image is a map of surface temperature. Every pixel represents a small patch of the scene, and the color of that pixel encodes how hot or cold the surface is relative to the rest of the frame. FLIR cameras do not see through walls, do not see moisture directly, and do not measure air temperature. What they capture is the long-wave infrared (typically 8 to 14 micrometers) emitted by every object warmer than absolute zero — which is everything.
The sensor inside the camera is a microbolometer, an array of tiny resistors whose values change with the heat hitting them. The electronics translate those changes into a temperature value per pixel and then assign a color from the active palette. The resulting image is the “FLIR image” most people recognize from inspector reports and YouTube videos.
Color palettes — the language of thermal pictures
FLIR cameras typically offer eight to ten palettes. A few dominate everyday work. Ironbow is the default for most inspectors: dark purple and black are cold, yellow and white are hot, with a smooth gradient between. Rainbow maps temperature across the visible spectrum (violet cold, red hot) and gives the highest visual contrast in a narrow temperature span. Arctic inverts the warm bias and is useful when the story is about cold anomalies — a cold-air leak around a window, for example. Lava and Grayscale are stylistic alternatives that some users prefer for printed reports.
Choosing a palette is a readability decision, not an accuracy one. The temperature values do not change; only their visual encoding does. Some FLIR models let you set a “level and span” — a narrow temperature window that makes small differences pop. A 1°C span on a wall that ranges from 18 to 19°C reveals studs and joists that a 30°C-span autoscale would hide.
Image-fusion: blending visible and thermal layers
Most FLIR cameras at the ONE Pro tier and above include a visible-light camera lens next to the thermal lens. The on-board processor combines the two streams, overlaying edge detail from the visible image onto the thermal layer. The result is a hybrid picture where you can tell which window the cold spot lives in, which outlet the hot blob belongs to, and which floor seam the streak runs along.
Without image-fusion, a thermal image of an interior wall is a colorful smear that is hard to orient in the room. With it, the same image becomes a readable diagnostic. FLIR’s marketing name for the technology is multi-spectral imaging, and most consumer models implement it as an adjustable slider between pure-thermal and pure-visible views. Inspectors typically settle around 30 to 50 percent overlay strength.
What common household problems look like in FLIR images
Insulation gaps
On a winter morning, with the indoor air warmer than outside, missing or compressed wall insulation appears as a cold rectangular patch bounded by warmer wood studs. Attic insulation gaps look like checkerboards from below, with the ceiling drywall coming up cold where the bays are empty. The image-fusion overlay shows the room’s outlet plate or window frame next to the cold zone so you know where to look.
Plumbing leaks
A leaking pipe behind drywall pulls heat out of the surrounding material as the water evaporates. The thermal image shows a cool streak running downward from a fitting, with sharper definition near the source. Hot-water leaks reverse the polarity — they show a warm plume instead. Either way, the camera flags the area; a moisture meter confirms whether water is actually present.
Electrical hotspots
A loose breaker connection or an overloaded conductor shows as a bright spot warmer than its neighbors. A panel image where one breaker is 15°F hotter than the others is a signal to call an electrician. The thermal image does not tell you the cause — corrosion, loose lug, undersized wire — only that the heat is there.
Roof leaks (from inside, sunny day)
Roof leaks are tricky. Looking up at a ceiling on a sunny afternoon, residual moisture in the attic decking sometimes shows as a cool patch that does not match the rafter pattern. This is the imaging technique that the Department of Energy references for whole-building thermal audits. Pair with an attic visual inspection.
Resolution: why some FLIR images look sharp and others look blurry
Sensor resolution drives apparent sharpness. A FLIR ONE Gen 3 at 80×60 thermal pixels produces an image that looks like a heavily pixellated mosaic. The same scene captured on a FLIR E96 at 1024×768 looks like a high-definition photograph with the temperature overlay. Image-fusion partially compensates for low thermal resolution by adding sharp visible-light edges, which is why the FLIR ONE Pro’s 160×120 sensor produces images that read more clearly than the raw pixel count suggests.
For homeowners comparing their own images to reference photos online, remember that most YouTube and forum reference images come from professional E-series or T-series cameras with much higher resolution. Your $300 attachment will see the same patterns but render them coarser. The pattern is what matters; the pixel count just changes how cleanly it shows up. For broader context on what a thermal scene contains, see the thermal camera image interpretation guide and the parent home inspection tools resource hub.
Reading a FLIR image — practical interpretation
Start by identifying the warmest and coolest spots in the frame. A FLIR camera typically marks them with a cursor or shows the temperature values on screen. Ask whether the difference is consistent with what should be there. A warm window in winter is a heater near it. A cold spot mid-wall with no fixture is an insulation void. A hot zone on a ceiling with no light fixture is the most-likely roof or solar heating issue.
Then check whether the pattern is geometric. Studs and joists make rectangular cold lines. Roof rafters make parallel warm stripes. Plumbing makes diagonal streaks that follow drain runs. Patterns that match construction features are usually structural; patterns that ignore them are anomalies that need investigation.
When the image is enough — and when it is not
A FLIR image is a screening tool. It shows surface temperature differences that suggest where a problem might be. It cannot prove moisture content, confirm electrical fault current, or guarantee that an insulation deficiency is the source of a heating bill. Follow-up always involves a more specific instrument — moisture meter, clamp meter, blower-door test, or visual disassembly.
Homeowners who post FLIR images to forums asking “is this a problem?” usually get the same answer: it might be, and the next step is X. The image alone almost never resolves the question. Treat the picture as a clue and budget for the follow-up work it implies.
Environmental conditions that change the image
Thermal images depend heavily on the conditions during capture. Three variables matter most. The temperature differential between indoor and outdoor air drives almost every useful homeowner finding. On a 20-degree morning with the heat on, an insulation gap shows up as a 10-15 degree cold patch. On a 65-degree spring afternoon, the same gap may show as a 1-2 degree difference that the camera can barely resolve. Plan thermal inspections for cold mornings or hot afternoons when the indoor-outdoor differential exceeds 20 degrees.
Sun loading creates false hot spots. A south-facing wall photographed at 2 p.m. in summer is hotter than its sibling walls — not because of insulation issues but because direct sunlight has been heating the surface. Capture exterior thermal images before sunrise or after sunset for accurate readings. Indoor images are less affected but still pick up sun warming through windows.
Wind cools exterior surfaces unevenly. A breeze hitting one corner of a house drops that surface temperature, creating apparent cold spots that are weather artifacts. Inspect on calm days for exterior thermal work.
Saving and sharing FLIR images
FLIR cameras save images in two formats. JPEG saves the rendered image as a standard photo file readable on any device. Radiometric files (FLIR’s .R-JPG or proprietary format) embed the per-pixel temperature data so the image can be re-processed later — different palette, different level-and-span, additional measurement points. The radiometric files are larger but preserve the underlying information; the JPEG-only path saves disk space but loses the data behind the colors.
For homeowner-level diagnostic work, JPEG is usually enough. For inspector reports or any image that might need post-capture analysis, save the radiometric file. FLIR Thermal Studio and Ignite both work with radiometric files; standard photo viewers do not.
References
- Home energy audits and thermal imaging — U.S. Department of Energy
- InterNACHI infrared inspection guidance — InterNACHI
- ASHI thermal-imaging practice resources — American Society of Home Inspectors
- IECC and thermal envelope reference — International Code Council
Thermal imaging cameras
Infrared cameras reveal hidden moisture, missing insulation, and air leaks. Phone-attachment models are the budget entry point; standalone units have higher resolution.
| Product | Why | Buy |
|---|---|---|
 FLIR ONE Pro (phone) | Plugs into iPhone/Android; inspector favorite. | Amazon — $329.00 |
 Topdon TC001 | High-res phone module at a low price. | Amazon — $199.99 |
 FLIR C5 Compact | Standalone pocket camera with Wi-Fi. | Amazon — $610.06 |