convertToWebP()

Converts images to the modern WebP format with configurable quality settings.

Signature

public function convertToWebP(
    string $inputImagePath,
    string $outputImagePath,
    int $quality = 80
): void

Parameters

`$inputImagePath` (string, required)

Path to the input image file. Supports JPEG, PNG, and GIF formats.

`$outputImagePath` (string, required)

Path where the WebP image will be saved. Should use .webp extension.

`$quality` (int, optional)

Quality level (0-100). Default: 80

Higher values = better quality, larger file
Lower values = worse quality, smaller file
Recommended: 75-90 for most use cases

Return Value

Returns void. Creates the output WebP file.

Behavior

Conversion Process

Opens the input image (JPEG, PNG, or GIF)
Validates quality parameter (0-100)
Converts to WebP format with specified quality
Saves to output path
Cleans up resources

Transparency Handling

PNG with transparency → WebP with transparency (preserved)
JPEG → WebP (opaque)
GIF → WebP (first frame only, transparency preserved)

Quality vs. File Size

WebP provides excellent compression:

Quality 90: ~30% smaller than JPEG at same quality
Quality 80: ~35% smaller than JPEG
Quality 70: ~40% smaller than JPEG

Examples

Basic Conversion

use Kenura\Imagick\ImageProcessor;

$processor = new ImageProcessor();

// Convert with default quality (80)
$processor->convertToWebP('photo.jpg', 'photo.webp');

Custom Quality

// High quality
$processor->convertToWebP('photo.jpg', 'high-quality.webp', 95);

// Balanced (recommended)
$processor->convertToWebP('photo.jpg', 'balanced.webp', 85);

// Smaller file
$processor->convertToWebP('photo.jpg', 'compressed.webp', 70);

Convert PNG with Transparency

// Transparency is preserved
$processor->convertToWebP('logo.png', 'logo.webp', 90);

Batch Conversion

$images = glob('photos/*.{jpg,png}', GLOB_BRACE);

foreach ($images as $image) {
    $filename = pathinfo($image, PATHINFO_FILENAME);
    $processor->convertToWebP($image, "webp/{$filename}.webp", 85);
}

With Size Comparison

$inputPath = 'photo.jpg';
$outputPath = 'photo.webp';

$originalSize = filesize($inputPath);

$processor->convertToWebP($inputPath, $outputPath, 85);

$webpSize = filesize($outputPath);
$savings = round((1 - $webpSize / $originalSize) * 100, 2);

echo "Reduced by {$savings}%\n";

Quality Guidelines

Recommended Settings

Use Case	Quality	File Size	Visual Quality
High-end photography	90-95	Medium	Excellent
Standard web images	80-85	Small	Very good
Thumbnails	70-80	Very small	Good
Icons/previews	60-70	Minimal	Acceptable

Quality Comparison

// Test different qualities
$qualities = [95, 85, 75, 65];

foreach ($qualities as $quality) {
    $processor->convertToWebP(
        'photo.jpg',
        "test-{$quality}.webp",
        $quality
    );
}

Format Support

Input Formats

Format	Support	Notes
JPEG	✅ Full	Best compression gains
PNG	✅ Full	Transparency preserved
GIF	✅ Partial	First frame only

Output Format

Always outputs WebP format, regardless of input.

Browser Support

WebP is supported by:

Chrome 23+
Firefox 65+
Edge 18+
Safari 14+ (macOS Big Sur)
Opera 12.1+

Fallback Strategy

Always provide fallback images:

// Create WebP version
$processor->convertToWebP('photo.jpg', 'photo.webp', 85);

// Keep JPEG fallback
copy('photo.jpg', 'photo-fallback.jpg');
// Or compress it
$processor->compressToJpg('photo.jpg', 'photo-fallback.jpg', 150);

Use in HTML:

<picture>
    <source srcset="photo.webp" type="image/webp">
    <img src="photo-fallback.jpg" alt="Photo">
</picture>

Performance

Typical Savings

Compared to original formats:

Original	WebP Quality 85	Savings
JPEG 100KB	~70KB	30%
PNG 200KB	~80KB	60%
GIF 150KB	~50KB	67%

Processing Speed

Typical conversion times:

Image Size	Time
4000x3000	~0.3s
1920x1080	~0.1s
800x600	~0.05s

Best Practices

1. Use Appropriate Quality

// ✅ Good: Balanced quality
$processor->convertToWebP('photo.jpg', 'photo.webp', 85);

// ❌ Bad: Unnecessarily high
$processor->convertToWebP('photo.jpg', 'photo.webp', 100);

// ❌ Bad: Too low quality
$processor->convertToWebP('photo.jpg', 'photo.webp', 30);

2. Always Use .webp Extension

// ✅ Good: Clear extension
$processor->convertToWebP('photo.jpg', 'photo.webp', 85);

// ⚠️ Confusing: Wrong extension
$processor->convertToWebP('photo.jpg', 'photo.jpg', 85);

3. Test Quality Levels

// Find the sweet spot for your images
foreach ([95, 85, 75, 65] as $quality) {
    $processor->convertToWebP('photo.jpg', "test-{$quality}.webp", $quality);
    // Compare visually
}

4. Provide Fallbacks

// Create both formats
$processor->convertToWebP('photo.jpg', 'photo.webp', 85);
$processor->compressToJpg('photo.jpg', 'photo.jpg', 150);

Common Issues

Issue: WebP not supported

Cause: GD library not compiled with WebP support

Solution: Check and install WebP support:

# Check if WebP is supported
php -r "echo function_exists('imagewebp') ? 'Supported' : 'Not supported';"

# Ubuntu/Debian
sudo apt-get install libwebp-dev
sudo apt-get install php-gd

# Rebuild PHP with WebP support if needed

Issue: Quality too low

Cause: Quality parameter too low

Solution: Increase quality:

// Increase from 60 to 85
$processor->convertToWebP('photo.jpg', 'photo.webp', 85);

Issue: File size not reduced

Cause: Input already optimized or quality too high

Solution: Lower quality or check input:

// Lower quality
$processor->convertToWebP('photo.jpg', 'photo.webp', 75);

// Check original size
echo filesize('photo.jpg') / 1024 . "KB\n";

Error Handling

Handle conversion errors:

<?php

use Kenura\Imagick\ImageProcessor;

$processor = new ImageProcessor();

try {
    // Check WebP support
    if (!function_exists('imagewebp')) {
        throw new Exception("WebP not supported");
    }

    // Validate input
    if (!file_exists('photo.jpg')) {
        throw new Exception("Input file not found");
    }

    // Convert
    $processor->convertToWebP('photo.jpg', 'photo.webp', 85);

    echo "✅ Conversion successful!";

} catch (Exception $e) {
    error_log("WebP error: " . $e->getMessage());
    echo "❌ Conversion failed.";
}

Combining with Other Operations

Resize and Convert

// Resize first
$processor->resizeImage('large.jpg', 'temp.jpg', 1920, 1080);

// Convert to WebP
$processor->convertToWebP('temp.jpg', 'final.webp', 85);

// Clean up
unlink('temp.jpg');

Watermark and Convert

// Add watermark
$processor->addWatermark('photo.jpg', 'temp.jpg', 'logo.png', 'bottom-right', 10);

// Convert to WebP
$processor->convertToWebP('temp.jpg', 'final.webp', 85);

// Clean up
unlink('temp.jpg');

Complete Workflow

// Resize, watermark, and convert
$processor->resizeImage('original.jpg', 'temp1.jpg', 1920, 1080);
$processor->addWatermark('temp1.jpg', 'temp2.jpg', 'logo.png', 'bottom-right', 10);
$processor->convertToWebP('temp2.jpg', 'final.webp', 85);

// Clean up
unlink('temp1.jpg');
unlink('temp2.jpg');

compressToJpg() - JPEG compression
resizeImage() - Resize before converting