---
name: "pfsabsolute"
section: "1"
platform: "linux"
package: "pfstools"
version: "2.2.0-9"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/pfsabsolute"
---

# pfsabsolute(1)

Convert luminance in images to absolute measure

## NAME

pfsabsolute - Convert luminance in images to absolute measure

## SYNOPSIS

**pfsabsolute** \<dest Y\> \[\<src Y\>\] \[--verbose\] \[--help\]

## DESCRIPTION

**pfsabsolute** applies all necessary operations to convert an image from relative luminance (tag LUMINANCE is RELATIVE) or display-dependent luma (tag LUMINANCE is DISPLAY) to absolute luminance values. When the luminance in an image is absolute (tag LUMINANCE set to ABSOLUTE), the Y channel represents physical luminance in cd/m^2. Absolute luminance levels are useful for some tone mapping algorithms and also for image or video compression.

The argument **\<dest Y\>** denotes the level of luminance that relative luminance **\<src Y\>** should be rescaled to. The luminance is in fact multiplied by the ratio \<dst Y\>/\<src Y\>. **\<src Y\>** is normally relative luminance checked with pfsview in the spot where the absolute luminance **\<dest Y\>** is measured, known or guessed. If **\<src Y\>** is omitted, the value 1 is assumed, so **\<dest Y\>** is just a scaling factor.

In case if display-depended luma (tag LUMINANCE is DISPLAY), the inverse gamma correction is applied (assuming sRGB color space). In such case **\<dest Y\>** is usually the maximum luminance of a display (e.g. 80 cd/m^2).

This command always sets LUMINANCE tag to ABSOLUTE.

## EXAMPLES

- pfsin memorial.hdr \| pfsabsolute 20 0.04 \| pfsview

  Multiply luminance in memorial image, so that relative luminance 0.04 becomes 20 cd/m^2. Normally, the value 0.04 is check using pfsview in the spot, where the absolute luminance (which equals in this case 20 cd/m^2) is known.

- pfsin lena.png \| pfsabsolute 80 \| pfsview

  Convert lena image from sRGB color space to absolute XYZ, assuming maximum luminance of the monitor 80 cd/m^2.

## SEE ALSO

[**pfsgamma**(1)](/pfsgamma/1.md) [**pfsinppm**(1)](/pfsinppm/1.md)

## BUGS

Please report bugs and comments to Rafal Mantiuk \<mantiuk@mpi-sb.mpg.de\>.