---
title: Encoding and lifecycle
description: Encode images, read metadata, handle errors, and release resources.
---

## Encode output

```dart
final png = image.encode(const PixerPngEncoder());
final jpeg = image.encode(PixerJpegEncoder(quality: 90));
final webp = image.encode(const PixerWebPEncoder());
```

Pixer also provides GIF, BMP, ICO, and TIFF encoders. JPEG quality accepts
values from 1 through 100 and defaults to 75.

## Read metadata

```dart
final metadata = image.getMetadata();
print('${metadata.width}x${metadata.height}, ${metadata.colorType}');

// Convenience getters use the same cached metadata.
print('${image.width}x${image.height}');
```

## Release resources

Every `Pixer` owns a Rust image handle. Always call `dispose()` when finished,
including for images returned by direct operations.

Native finalizers are a safety net, but they are not guaranteed to run. Web
builds require explicit disposal.

## Handle errors

Pixer throws typed exceptions:

| Exception | Cause |
| --- | --- |
| `InvalidPathException` | Empty or invalid file path |
| `IoException` | File read or write failure |
| `DecodingException` | Image bytes cannot be decoded |
| `EncodingException` | Image cannot be encoded |
| `UnsupportedFormatException` | Image format is unsupported |
| `InvalidDimensionsException` | Invalid dimensions or crop bounds |
| `InvalidPointerException` | Image was already disposed |
| `InvalidParameterException` | A scalar parameter is out of range |
| `UnknownException` | Unclassified native failure |