Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Recommend using extended transfer functions to handle negative values #434

Merged
merged 2 commits into from Mar 4, 2024
Merged

Recommend using extended transfer functions to handle negative values #434

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
f3d4d5b
Recommend using extended transfer functions to handle negative values…
svgeesus Mar 1, 2024
40e819b
Define EOTF and OETF
svgeesus Mar 1, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
23 changes: 23 additions & 0 deletions index.html
View file
Open in desktop
Expand Up @@ -711,6 +711,12 @@ <h2 id="3Defsandabbrevs">Terms, definitions, and abbreviated terms</h2>
<dd>vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a
phosphorescent screen.</dd>

<dt>Electro-Optical Transfer Function</dt>
<dt>
<abbr title="Electro-Optical Transfer Function">EOTF</abbr>
</dt>
<dd>The <a>transfer function</a> between the electrical or digital domain and light energy. It defines the amount of light emitted by a display for a given input signal.</dd>

<!-- Maintain a fragment named "3LSB" to preserve incoming links to it -->
<dt id="3LSB">Least Significant Byte</dt>
<dt><abbr title="Least Significant Byte">LSB</abbr></dt>
Expand All @@ -724,6 +730,12 @@ <h2 id="3Defsandabbrevs">Terms, definitions, and abbreviated terms</h2>
<dd>
Most significant byte of a multi-<a>byte</a> value.
</dd>

<dt>Opto-Electrical Transfer Function</dt>
<dt>
<abbr title="Opto-Electrical Transfer Function">OETF</abbr>
</dt>
<dd>The <a>transfer function</a> between light energy and the electrical or digital domain. It defines the amount of light in a scene required to produce a given output signal.</dd>
</dl>
</section>
<!-- ************Page Break******************* -->
Expand Down Expand Up @@ -3725,6 +3737,17 @@ <h2><span class="chunk">cICP</span> Coding-independent code points for video sig
PNG format, it should be noted that this format is not part of the [[ITU-R-BT.709]] standard.
</aside>

<p>If <code>Video Full Range Flag</code> is <code>0</code>
(a <a>narrow-range image</a>), recommended practice
is to define transfer functions
such as <a>EOTF</a> or inverse <a>OETF</a>
over the extended range,
so as to include negative values.
This is done as follows:
</p>

<pre>out = sign(in) * TransferFunction(abs(in))</pre>

<p>The <span class="chunk">cICP</span> chunk MUST come before the <a class="chunk" href="#11PLTE">PLTE</a> and <a class=
"chunk" href="#11IDAT">IDAT</a> chunks.</p>

Expand Down