Image Compressor

The role of an image compressor.

A compressor is not simply a tool that shrinks files in a generic sense, but a tool that discards information from files that you typically do not need to view. You can find a lot of information redundancy in photos; repeated colors, subtle changes in contrast, or details at the pixel level that the human brain cannot see as simplified. Compression discards that redundant information while retaining the “structure” that can be seen by human eyes.

There are two methods and knowing the difference will help you choose the right settings:

• Lossy compression doesn't reduce the image in a precise manner, so it gets a lot more dramatic when reducing the size of your image, it will often be 60–90% smaller. Both JPEG and WebP use lossy compression. For most viewers, the difference will not be visible at reasonable quality settings (75 to 85%), but at higher settings you'll begin to notice blocky artifacts or color banding.
• Lossless compression efficiently repackages existing image data without discarding any data. The result is the same as the original, but stored more efficiently. PNG compression and tools such as this that compress PNG color palettes are more like this — there are real savings (usually 50%+), and there is no visible difference.

The different types of formats and when to use them

• JPEG (.jpg/.jpeg) — suitable for photographs and images that have many different colors. Very compact, ideal for product photos, blog images, and portfolios.
• PNG — for screenshots, logos, icons, and for any picture with a transparent background. PNG files are bigger than JPEGs, so there's more room to compress.
• WebP is a new format specifically designed for the web. It will usually be 25-35% smaller than an equivalent JPEG, at the same visual quality, so it's especially recommended for page-speed in Google.
• GIF — mainly used for short animations. Compression is done here to shrink the colour range not the resolution.
• SVG — vector graphics that are used for logos and icons. Compression removes unneeded code and metadata, not pixel data.

To make it easy, for photographs JPEG or WebP, for graphics, flat colors or transparent, PNG, and for animations, WebP (it is now capable of animation, and beats GIF in file size almost always).

Compressing an image in 3 steps

1. Upload your file(s). Drag and drop, or select from your device. Saves you from having to compress individual photos or blog images, batch uploads are available.
2. Allow tool to auto-optimize or fine tune it personally. The default settings are optimized for the “sweet spot” of taking a balance between file size and visual quality for most situations. For more control, you'll be able to see the exact nature of any compromise by using the quality slider or side-by-side comparison view.
3. Save your compressed image. Save as single files or collect the entire pack as a single ZIP file.

Most people don't realize just how important image file size is.

• The performance of pages and Core Web Vitals. Images are usually the one biggest item in a webpage. Google's Core Web Vitals directly track the speed at which your main content (usually a hero image) appears, which in this case is Largest Contentful Paint. The most common issue with achieving a good LCP score is bloated images, and page speed is a scientifically proven ranking factor for Google.
• Mobile users and data costs. These days, a huge percentage of web traffic is generated from mobile connections and each single megabyte carries with it the user's patience and data plan. This is clearly reflected in bounce rate, as compressed images load much faster across any sort of 4G or fragmented Wi-Fi.
• Storage and bandwidth costs. Uncompressed images will increase your hosting and CDN costs if you're using an ecommerce platform or a site with lots of media content. You can make a 70% reduction in the average image size and make a significant reduction in your monthly bandwidth costs.
• Limit on email/messaging. A typical email provider will allow attachments of approximately 25MB. Before sending photos, it's often the case that compressing will mean the difference between a message going through or bouncing.

So does compression degrade the quality of an image?

It may do so, but it does not need to. The vast majority of people can't tell when a JPEG/WebP image has been compressed, at moderate settings (around 75-85% quality for JPEG/WebP). Quality loss is only apparent when you compress too hard to get the smallest files possible, or when you compress the same lossy file again and again (the compression quality will worsen with each save). It's best to compress just once from the original source file, at a reasonable quality level.

Are there any online images worth compressing?

Reliable compressors work over an encrypted link and remove the files automatically after a brief period of time—be sure to read any tool's privacy policy before entrusting sensitive photos with it. The tools that use WebAssembly to run the compression within your browser take it one step further: the images don't leave your device at all, which might be important if you're processing sensitive or personal photos. As a bonus, photos are also automatically stripped of EXIF data (camera model, GPS location, timestamp) when compressed, which is good to do before posting personal images online.

Frequently Asked Questions