Tone mapping is the process of compressing the wide dynamic range of an HDR source into the narrower range a display or print can actually show, while preserving as much perceptual realism as possible. A scene captured across multiple bracketed exposures or in a single high-bit-depth raw might span 14 to 20 stops, but the screen the image will be viewed on can show roughly 8 to 10 stops, and a print perhaps 6 to 7. Tone mapping is the bridge between those two ranges.
Two broad classes of algorithms are used. Global tone mapping applies a single curve to the entire image, much like a heavy tone curve applied to a raw file. It is fast, predictable, and preserves global contrast relationships, but it cannot do much for scenes where both shadows and highlights need attention. Local tone mapping, by contrast, analyzes the image regionally and applies different mapping curves to different areas, which is how shadow detail and highlight detail can both be lifted into the visible range without an overall low-contrast pancake of an image.
Done well, tone mapping looks like a natural photograph that simply happens to show extraordinary range, with detail in both the cathedral interior and the bright stained-glass windows visible at once. Done poorly, it produces the over-cooked, hyper-saturated, halo-laden HDR look that dominated landscape photography in the mid-2000s, where every cloud glowed and every shadow was lifted to the point of unreality. The technical capability is the same; the difference lies in restraint and in algorithmic choices.
Modern workflows often dispense with the dedicated HDR-merge-then-tone-map pipeline in favor of single-raw editing combined with exposure blending by hand. A 14-stop raw from a recent sensor has enough headroom that careful masking and per-region adjustments produce results indistinguishable from multi-exposure HDR for most scenes. The remaining cases, very high-contrast architectural interiors with sun-lit exteriors, astrophotography composites, and similar edge cases, still benefit from explicit tone-mapping software like Photomatix or Aurora HDR.
Display-side tone mapping is also a factor. HDR-capable monitors and televisions perform their own dynamic range adaptation, and the same image file can look quite different on an SDR display and an HDR-10 display. Photographers preparing work for both should review on a calibrated SDR monitor at the intended output brightness, since the majority of viewers will see SDR versions on phones and laptops regardless of the master file’s capabilities.
Common pitfalls include pushing local contrast until edge halos appear, over-saturating colors that were already at the limit of the color space, and forgetting that a heavily tone-mapped JPEG cannot be undone. Saving the layered, high-bit-depth master file separately from the exported view preserves the ability to retreat from extreme processing when the look ages out of fashion.