Added scanning barcodes with a camera

quagga2/quagga2-1.12.1/docs/how-to-guides/optimize-performance.md

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+# Optimize Performance {#optimize-performance}
+
+This guide covers techniques to improve Quagga2's barcode scanning performance.
+
+## Overview {#overview}
+
+Performance optimization in Quagga2 involves balancing accuracy against speed. The key areas to optimize are:
+
+- Input resolution and scaling
+- Locator configuration
+- Reader selection
+- Processing frequency
+
+## Input Resolution {#input-resolution}
+
+### Using `inputStream.size` {#inputstream-size}
+
+Reducing the processing resolution is the most effective way to improve performance:
+
+```javascript
+Quagga.init({
+  inputStream: {
+    size: 640  // Process at 640px max dimension instead of full resolution
+  }
+});
+```
+
+**Recommended values:**
+- **1280px** - High quality, slower (good for static images)
+- **800px** - Balanced (default for `decodeSingle`)
+- **640px** - Fast (recommended for live scanning)
+- **480px** - Very fast (may reduce accuracy)
+
+### Camera Constraints {#camera-constraints}
+
+Request only the resolution you need:
+
+```javascript
+inputStream: {
+  constraints: {
+    width: { ideal: 1280 },
+    height: { ideal: 720 }
+  }
+}
+```
+
+## Locator Configuration {#locator-configuration}
+
+### Half Sampling {#half-sampling}
+
+Keep `halfSample: true` (default) for faster localization:
+
+```javascript
+locator: {
+  halfSample: true  // Processes at half resolution
+}
+```
+
+### Patch Size {#patch-size}
+
+Larger patch sizes are faster but may miss small barcodes:
+
+```javascript
+locator: {
+  patchSize: "large"  // Options: x-small, small, medium, large, x-large
+}
+```
+
+## Reader Selection {#reader-selection}
+
+Only enable the barcode formats you need:
+
+```javascript
+decoder: {
+  readers: ["code_128_reader"]  // Don't enable all readers
+}
+```
+
+## Processing Frequency {#processing-frequency}
+
+Limit scan rate to reduce CPU usage:
+
+```javascript
+Quagga.init({
+  frequency: 10  // Max 10 scans per second
+});
+```
+
+## Disable Localization {#disable-localization}
+
+If barcode position is fixed, disable localization entirely:
+
+```javascript
+Quagga.init({
+  locate: false,
+  inputStream: {
+    area: {
+      top: "25%",
+      right: "25%",
+      bottom: "25%",
+      left: "25%"
+    }
+  }
+});
+```
+
+## Related {#related}
+
+- [Configuration Reference](../reference/configuration.md) - All configuration options
+- [How Barcode Localization Works](../explanation/how-barcode-localization-works.md) - Understanding the algorithm
+
+---
+
+[← Back to How-To Guides](index.md)