how to compress images in WordPress without plugin

Understanding Image Compression in WordPress

Image compression plays a pivotal role in website performance, reducing load times, saving bandwidth, and providing a smoother user experience. WordPress, while equipped with numerous plugins for this task, can also handle image compression manually, offering webmasters control over their media without the need for additional software.

Step 1: Choose the Right Image Format

Before uploading images to WordPress, choosing the right format is crucial. The most commonly used formats include JPEG, PNG, and WebP. JPEG is ideal for photographs with complex coloring, while PNG is better for images requiring transparency or those with less color data. WebP, a newer format, provides superior compression and quality characteristics compared to JPEG and PNG. Convert your images to the appropriate format using tools like Adobe Photoshop or free online converters such as CloudConvert.

Step 2: Manually Resize Images

One of the simplest ways to reduce image size is by resizing them before upload. WordPress automatically creates multiple versions of uploaded images, which often results in unnecessary duplication if images are already optimized. Using an image editor, resize your images to the maximum width and height that they will be displayed on your website. Tools like GIMP (a free software) offer straightforward options to adjust pixel dimensions.

Step 3: Compression Before Upload

Once you have the right format and size, the next step is compressing the image file. Many online tools like TinyPNG or TinyJPG provide efficient compression while maintaining reasonable image quality. These services require you to upload your image, and then download the compressed version. This process removes unnecessary metadata from images, reducing file size without a noticeable drop in quality.

Step 4: Utilize WordPress’ Built-In Features

WordPress has built-in features that can further optimize your images. When uploading images, WordPress automatically compresses them to about 82% of their original quality. You can alter this setting by adding a code snippet to your theme’s functions.php file:

add_filter('jpeg_quality', function($arg){return 80;});

This snippet changes the default compression rate to 80%, which can be adjusted based on your preferences.

Step 5: Serve Scaled Images

Serving scaled images means sending an image that is precisely as large as required by the page, no larger. Check the size at which images are actually displayed on your site. You can use the browser’s Developer Tools to inspect elements and find the actual display dimensions. Adjust the image dimensions before uploading them to match these display sizes.

Step 6: Enable Lazy Loading

Lazy loading is a technique that defers loading of non-critical resources at page load time. Instead, items are only loaded as they are needed (when they enter the viewport). This can significantly speed up page loads and save bandwidth. WordPress has built-in support for lazy loading images starting from version 5.5. You can enable this feature by ensuring your site runs on the required WordPress version or higher.

Step 7: Use CSS Sprites

For websites using many small images like icons or buttons, CSS sprites can be beneficial. A sprite is a collection of images put into a single image. A web page with many small images can slow down the site as each image causes a separate server request. Combining images reduces the number of server requests. Tools like SpritePad can help you create sprites with ease.

Best Practices for Image Optimization in WordPress

Continuously monitor the size of the images and the impact on page speed using tools like Google PageSpeed Insights. Consider updating images with improved versions and removing unused or less important images. Educate yourself on new image formats and compression techniques as technology advances.

By manually optimizing images, you gain greater control over the performance and appearance of your WordPress site. While it requires more effort than using a plugin, the increased understanding of how your website functions and the potential for refined optimizations are beneficial for webmasters aiming for maximum efficiency and performance.