A camera sensor can record a limited range of brightness in one exposure — far less than your eye. Point it at a person in front of a bright window and you must choose: a correctly exposed face with a white window, or a visible window with a silhouetted face. HDR exists to avoid that choice.
How It Works
- Capture multiple exposures in quick succession — one for the highlights, one for the midtones, one for the shadows. Modern phones capture several frames continuously and use whichever data they need.
- Merge them into a single image containing detail across the whole range.
- Tone map the result back into a normal image format, since standard JPEGs can't hold that range. This is the crucial step: the extended range must be *compressed* into what a normal display can show.
That third step is where HDR gets its reputation, good and bad.
Why HDR Sometimes Looks Fake
Aggressive tone mapping produces the classic over-processed look:
- Flat, low-contrast images — everything is midtone-grey because both shadows and highlights were pulled toward the middle.
- Halos around high-contrast edges, especially along skylines and rooflines.
- Unnatural local contrast where texture is exaggerated.
- Muddy colours from over-lifted shadows.
Contrast isn't a flaw — it's how we perceive depth and drama. An image with *no* deep shadows and *no* bright highlights looks lifeless, which is why "more dynamic range" is not automatically better.
HDR Photos vs HDR Displays
Two different things share the name:
- HDR photography — merging exposures and compressing them into a standard image.
- HDR display / HDR image formats — screens and file formats that can actually *show* a wider range, with genuinely brighter highlights.
Newer phones capture and display true HDR images, which look spectacular on a compatible screen and often look washed out or oddly bright when shared to systems that don't support them. If your photos look strange after sending, an HDR-to-SDR mismatch is a likely cause.
When to Turn It Off
- Moving subjects. Multiple frames merged means ghosting if anything moved between them. Sport, kids, pets — turn HDR off or rely on the phone's fast single-frame mode.
- When you want silhouettes. HDR will "helpfully" recover the shadow detail you deliberately wanted to lose.
- Dramatic light. A single shaft of light through a dark room is the picture; HDR flattens it into an evenly lit room.
- Deliberately dark or high-contrast moods — concerts, night scenes, moody portraits.
- When shooting RAW — you often have enough latitude in a single RAW file to recover highlights and shadows yourself, with more control and no merging artifacts.
Practical Advice
Leave HDR on auto for everyday shooting; modern implementations are subtle and genuinely helpful for the backlit-window problem they were built to solve. Switch it off deliberately for motion and for images where contrast *is* the point. And if you shoot RAW, treat HDR as a fallback rather than the default — one well-exposed RAW frame with recovered highlights usually beats a merged, tone-mapped JPEG.