_          _          ___                      
| |        | |        /   |                     
| |__    __| | _ __  / /| | _ __   _ __    __ _ 
| '_ \  / _` || '__|/ /_| || '_ \ | '_ \  / _` |
| | | || (_| || |   \___  || |_) || | | || (_| |
|_| |_| \__,_||_|       |_/| .__/ |_| |_| \__, |
                           | |             __/ |
                           |_|            |___/ 

INTRODUCTION

hdr4png is a Python script that adds an specially-crafted iCCP chunk to PNG images according to Using the ITU BT.2100 PQ EOTF with the PNG Format WG Note. The latter specification uses the iCCP chunk to unambiguously signal the color system of an image that uses the Reference PQ EOTF specified in ITU BT.2100-1. It also allows graceful processing by decoders that do not conform to this specification by recommending fallback values for the gAMA chunk, cHRM chunk, and embedded ICC profile.

NOTE: hdr4png does not convert SDR images to HDR images, but merely adds an iCCP chunk. The input image must contain pixels that already conform to the ITU BT.2100 PQ color system

DEPENDENCIES

(required) Python 3.4 or higher

EXAMPLE USAGE

python hdr4png.py -p ITUR_2100_PQ_FULL ITUR_2100_PQ_FULL.icc in.png out.png

where ITUR_2100_PQ_FULL.icc can be retrieved from Using the ITU BT.2100 PQ EOTF with the PNG Format WG Note, and is also includes under lib/png-hdr-pq.

SAMPLES

The examples directory contains PNG files processed by this tool (processed suffix) as well as the corresponding source file (source suffix).

NOTABLE DIRECTORIES AND FILES

src/hdr4png.py                      Main script
examples                            Sample PNG files