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181 lines
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{"@context":"https://schema.org","@type":"WebPage","description":"The friendly multilateral video toolkit built for artists by artists.","headline":"gamma_fix","publisher":{"@type":"Organization","logo":{"@type":"ImageObject","url":"http://localhost:4000/videobeaux/assets/img/videobeaux.png"}},"url":"http://localhost:4000/videobeaux/programs/utilities/gamma_fix.html"}</script>
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<body>
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<div class="wrapper">
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<header>
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<h1><a href="http://localhost:4000/videobeaux/">videobeaux</a></h1>
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<img src="/videobeaux/assets/img/videobeaux.png" alt="Logo" />
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<p>The friendly multilateral video toolkit built for artists by artists.</p>
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<p class="view"><a href="https://github.com/schwwaaa/videobeaux">View the Project on GitHub <small>schwwaaa/videobeaux</small></a></p>
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</header>
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<section>
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<h1 id="gamma_fix">gamma_fix</h1>
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<p>:contentReference[oaicite:1]{index=1}</p>
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<h2 id="description">Description</h2>
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<p>Normalizes gamma, brightness, and exposure levels for broadcast-safe or web-safe consistency across diverse footage.</p>
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<h2 id="purpose">Purpose</h2>
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<p><code class="language-plaintext highlighter-rouge">gamma_fix</code> is designed to correct inconsistent exposure, contrast, and gamma shifts that often appear when mixing footage from multiple cameras, phones, archives, or lighting conditions.<br />
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It provides predictable luminance normalization suitable for:</p>
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<ul>
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<li>web delivery,</li>
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<li>broadcast pipelines,</li>
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<li>archival stabilization,</li>
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<li>color prep before LUTs or grading.</li>
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</ul>
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<h2 id="how-it-works">How It Works</h2>
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<ol>
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<li><strong>Luma Analysis</strong><br />
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The program evaluates input brightness and computes adjustments toward <code class="language-plaintext highlighter-rouge">target_yavg</code>.</li>
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<li><strong>Contrast Shaping</strong><br />
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<code class="language-plaintext highlighter-rouge">min_contrast</code> and <code class="language-plaintext highlighter-rouge">max_contrast</code> constrain the allowed contrast stretch, preventing overcorrection.</li>
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<li><strong>Gamma Adjustment</strong><br />
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A user-specified gamma curve can brighten or darken midtones without clipping shadows or highlights.</li>
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<li><strong>Saturation Shaping</strong><br />
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<code class="language-plaintext highlighter-rouge">sat</code> provides global saturation control to compensate for washed-out or overly vivid sources.</li>
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<li><strong>Legalization</strong><br />
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When enabled, <code class="language-plaintext highlighter-rouge">legalize</code> ensures output luminance stays within broadcast-safe IRE ranges.</li>
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<li><strong>Encoding</strong><br />
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Output is encoded using the selected codec, preset, and CRF.</li>
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</ol>
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<h2 id="program-template">Program Template</h2>
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<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>videobeaux -P gamma_fix \
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-i input.mp4 \
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-o output.mp4 \
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--target_yavg VALUE \
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--min_contrast VALUE \
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--max_contrast VALUE \
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--gamma VALUE \
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--sat VALUE \
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--legalize VALUE \
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--vcodec VALUE \
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--crf VALUE \
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--preset VALUE \
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--acodec VALUE \
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--ab VALUE
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</code></pre></div></div>
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<h2 id="arguments">Arguments</h2>
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<ul>
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<li><strong>target_yavg</strong> — Target brightness (luma average) to normalize toward.</li>
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<li><strong>min_contrast</strong> — Minimum allowed contrast level after adjustment.</li>
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<li><strong>max_contrast</strong> — Maximum allowed contrast level after adjustment.</li>
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<li><strong>gamma</strong> — Gamma correction multiplier for shaping midtones.</li>
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<li><strong>sat</strong> — Saturation adjustment factor.</li>
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<li><strong>legalize</strong> — Ensures output levels conform to broadcast-safe luminance ranges.</li>
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<li><strong>vcodec</strong> — Video codec to use for output (e.g., <code class="language-plaintext highlighter-rouge">libx264</code>).</li>
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<li><strong>crf</strong> — Constant Rate Factor controlling video quality.</li>
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<li><strong>preset</strong> — Encoding speed/quality preset.</li>
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<li><strong>acodec</strong> — Audio codec.</li>
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<li><strong>ab</strong> — Audio bitrate.</li>
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</ul>
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<h2 id="real-world-example">Real World Example</h2>
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<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>videobeaux -P gamma_fix \
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-i myvideo.mp4 \
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-o gamma_fix_styled.mp4 \
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--target_yavg EXAMPLE \
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--min_contrast EXAMPLE \
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--max_contrast EXAMPLE \
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--gamma EXAMPLE \
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--sat EXAMPLE \
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--legalize EXAMPLE \
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--vcodec EXAMPLE \
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--crf EXAMPLE \
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--preset EXAMPLE \
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--acodec EXAMPLE \
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--ab EXAMPLE
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</code></pre></div></div>
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<h2 id="technical-notes">Technical Notes</h2>
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<ul>
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<li>Gamma correction subtly adjusts midtone brightness without flattening highlights.</li>
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<li>Luma averaging helps normalize footage from mixed sources with inconsistent exposure.</li>
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<li>Excessive contrast stretching may introduce noise—use moderate ranges for natural results.</li>
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<li>Broadcast-safe legalization prevents clipped peaks in deliverables meant for TV or streaming platforms.</li>
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<li>Saturation adjustments apply globally; fine-grained color correction should be done in grading tools.</li>
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</ul>
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<h2 id="recommended-usage">Recommended Usage</h2>
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<ul>
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<li>Normalizing multi-camera footage before editing.</li>
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<li>Preparing consistent brightness for LUT workflows or grading.</li>
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<li>Fixing underexposed or flat-looking archive material.</li>
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<li>Making levels compliant for broadcast delivery requirements.</li>
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</ul>
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<h2 id="quality-tips">Quality Tips</h2>
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<ul>
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<li>Start with small gamma adjustments for natural tonal shifts.</li>
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<li>Set <code class="language-plaintext highlighter-rouge">target_yavg</code> close to typical mid-gray values (around 40–55% normalized luma).</li>
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<li>Use moderate <code class="language-plaintext highlighter-rouge">sat</code> boosts (1.05–1.15) to avoid color clipping.</li>
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<li>Lower CRF (14–18) retains quality when making heavy tonal corrections.</li>
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<li>Always inspect waveform before and after applying legalization.</li>
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</ul>
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</section>
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<footer>
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<p>This project is maintained by <a href="https://github.com/schwwaaa">schwwaaa</a></p>
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<p><small>Hosted on GitHub Pages — Theme by <a href="https://github.com/orderedlist">orderedlist</a></small></p>
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