Render Tonemap

Reinhard / Uncharted(Hable) / HBD operators in linear

render_tonemap(
  image,
  method = c("raw", "reinhard", "uncharted", "hbd"),
  exposure_bias = 2,
  W = 11.2,
  filename = NULL,
  preview = FALSE
)

Arguments

image

Default NULL. 3/4-channel array, rayimg, or filename.

method

Default raw. One of "raw", "reinhard", "uncharted", "hbd". Chooses the global tone-mapping curve. "raw" leaves the image unchanged. "reinhard" applies a classic shoulder that gently compresses highlights. "uncharted" (Hable filmic) gives a film-style toe/shoulder and keeps mid-tones contrasty. "hbd" is a fast filmic-like curve with a soft toe/shoulder. All methods operate on linear RGB and return display-referred linear (no OETF).

exposure_bias

Default 2. Only for "uncharted". Scalar applied to the linear RGB channels before the Uncharted/Hable curve (i.e., a pre-curve exposure gain). Values >1 brighten; <1 darken. exposure_bias=2 is about +1 stop; 0.5 is about −1 stop.

W

Default 11.2. White (linear scene value) that maps to 1.0 after the Uncharted/Hable/Reinhard curve. Acts like a “white point” for the shoulder: larger values preserve more highlight detail (later roll-off), smaller values roll off earlier and harder.

filename

Default NULL. Output path.

preview

Default FALSE. Show result.

Value

A rayimg RGBA array.

Examples

# Plot unchanged image
render_tonemap(dragon, preview = TRUE)

# Plot Reinhard tonemapped image
render_tonemap(dragon, method = "reinhard", preview = TRUE)

# Plot Uncharted/Hable tonemapped image
render_tonemap(dragon, method = "uncharted",preview = TRUE)

# Plot Uncharted/Hable tonemapped image, white point adjusted
render_tonemap(dragon, method = "uncharted", W=11.4, preview = TRUE)

# Plot Uncharted/Hable tonemapped image, exposure adjusted
render_tonemap(dragon, method = "uncharted", exposure_bias = 1,preview = TRUE)

# Plot Hejl-Burgess-Dawson tonemapped image, exposure adjusted
render_tonemap(dragon, method = "hbd",preview = TRUE)