View source for HDR

{{LanguageBar|title=HDR rendering}}

[[File:HL2_LostCoast_17.jpg|thumb|right|An overexposed image from {{hl2lc|4}}]]

[[File:Source_HDR_comparison.jpg|thumb|right|Comparison between LDR, LDR with Bloom and [[HDR]] ({{code|mat_hdr_level 0/1/2}} respectively).]]

'''High Dynamic Range''' ('''HDR'''), in {{src|4}} and {{src2|4}} (and most games in 2000s), refers to '''High Dynamic Range rendering''' ('''HDR Rendering''' for short, or '''HDR lighting'''), which simulates brightness above that which a computer monitor is capable of displaying, before downconverting to {{w|Standard dynamic range|Standard Dynamic Range}} (SDR, internally referred to in {{src|1}} and {{src2|1}} as '''LDR''', for '''Low Dynamic Range''') video. This mainly involves "blooming" colors above 100% brightness into neighboring areas and adjusting a virtual camera [[W:aperture|aperture]] to compensate for any over-exposure that results.

Besides the obvious effects of this (see right), HDR gives richer colors and finer gradients: since bright and dark areas are pushed into white and black, correctly exposed areas are drawn with a far wider range of values.

== Predecessor to HDR ==
{{csxbox|3.1}}, a {{gldsrc|1}} game, had a feature called "'''Dynamic iris simulation'''". This adjusts the screen brightness depending on where you look.

== HDR in Source ==
'''HDR rendering''' is first introduced with {{Hl2lc|3.1}}, a tech demo, along with {{dods|3.1}}, released in Sep 2005, and later available with {{src06|2}} and subsequent Source branches. HDR requires DirectX 9 ({{code|dxlevel 90}} or higher) level GPU for {{win|1}} (or OpenGL 1.4 and later for {{mac|1}}/{{linux|1}}), and maps must be compiled with HDR lighting data. It is optional but recommended that the map's skybox textures are HDR-capable.

Even through HDR was introduced in Source 2006, initially in certain games such as {{css|2}}, {{hl2|2}} (both at the time having been upgraded to {{src06|name}}), not all maps were compiled with HDR support until the engine (and Mac) update in 2010, upgrading it to {{src09|2}} along with changes to the maps and skybox textures to support HDR.

However, as of today (with both CSS and HL2 are running on {{src13|1}}), Valve forgot to compile all the maps with both LDR and HDR support in {{hl2|1}}, leaving some of the maps LDR only, and others HDR only, requiring users to enable HDR, otherwise the HDR-only map will be rendered in fullbright.

Additionally, {{Src07|3.1}} improves HDR through remade HDR tonemapping in order to better fits outdoor scenes. This may results in brighter or darker image, if tonemapping was not adjusted.

=== Limitations ===
{{src|4}} does not have a physically accurate HDR simulation. Its camera has a far wider range than the human eye (let alone real cameras), and it also adjusts to changes in brightness far faster (this can be adjusted through {{mono|[[env_tonemap_controller]]}}'s {{code|SetTonemapRate}} [[keyvalue]] however). Both of these are expedient to gameplay of course, especially in multiplayer.

==== HDR display output ====
Source '''does not''' create "''proper''" HDR images, and does not support native HDR output for HDR-capable TV/monitors. Instead, [https://steamcdn-a.akamaihd.net/apps/valve/2006/SIGGRAPH06_Course_HDRInValvesSourceEngine_Slides.pdf it collapses the image down to SDR early], like many other games in the 2000s/early 2010s due to hardware and software limitations at the time. The only Source engine game that currently support native HDR output is {{Apex|1}} on consoles, and it requires HDR-capable TV/monitors.

The average user would be hard-pressed to tell the difference, however, and the benefits include support for all DX9+ GPUs, [[MSAA]] compatibility, and excellent performance.

=== LDR deprecation in newer games ===
Since the {{l4dbranch|2}} and later games (with some exceptions), HDR rendering is now required and LDR/SDR rendering has been deprecated, with the option to disable HDR removed.
{{note|Third-party games like {{tf2c|2}} also require HDR}}

Despite LDR being deprecated since {{l4d|2}}, some games like {{p2|2}} as well as the original release of {{dota2|2}} allow users to disable HDR through console commands, however:
*In Portal 2, while you can disable HDR using console commands ({{code|mat_hdr_level 0}}), no Portal 2 maps have LDR lighting compiled by default, which will cause "{{code|[[mat_fullbright]]}}" ('full bright' lighting) to be enabled.
*In the original release of Dota 2, the game only uses LDR lighting, and none of the maps appear to have HDR lighting data. Additionally the game does not have an option to enable HDR aside from using console commands.
* In {{l4d|2}} and {{l4d2|2}}, HDR can be only disabled via the launch command ({{code|mat_hdr_level 0}}) as the command is hidden ingame, but you can use SourceMod (for {{l4d}}) or VScript (for {{l4d2}}) to disable it while the game is already running.
** {{L4d}} {{code|sm_cvar mat_hdr_level 0/1/2}} command (with [[SourceMod]] installed) or </br>{{L4d2}} {{code|script Convars.SetValue("mat_hdr_level", "0/1/2")}} (using [[VScript]]).

== HDR in Source 2 ==
{{todo|How does {{src2}} improve HDR?}}
{{Cs2|4}} adds a option for switching between Performance and Quality HDR.

== See also ==
* [[HDR Lighting Basics]]
* [[Advanced HDR]]
* [[HDR Lighting Settings]]
* [[HDR Skybox Creation]]
* {{ent|env_tonemap_controller}}
== External links ==
* {{Wikipedia|High dynamic range rendering}}
* {{Wikipedia|Standard-dynamic-range video}}

[[Category:Source]]
[[Category:Lighting]]
[[Category:HDR]]