Free online utilities for PDF compression and image resizing
Resize JPG, PNG, GIF, WebP, BMP and TIFF images while controlling their maximum dimensions, output format and image quality. QuakeStar currently allows up to 7 file conversions every 2 hours.
Conversions remaining: 7
Digital images are made from pixels. A photograph that is 4,000 × 3,000 pixels contains 12 million pixels. That amount of detail may be useful for editing or printing, but it is often far more than is needed for a website, presentation or email.
Reducing the dimensions to 1,200 × 900 leaves fewer than 1.1 million pixels. That reduction can make the resulting file dramatically smaller because there is much less image data to store.
An image's aspect ratio describes the relationship between its width and height. A 4,000 × 3,000 photograph, for example, has a 4:3 aspect ratio.
When Maintain aspect ratio is enabled, QuakeStar scales the width and height together. If the width is reduced, the height is adjusted proportionally so that the image is not stretched or squeezed. For most ordinary resizing jobs, leaving this option enabled is the safest choice.
The width and height settings define the largest dimensions you want the resulting image to have. This is useful when you know an image must fit within a particular space but do not want to calculate the new dimensions yourself.
For example, if an image is substantially larger than a website requires, setting a reasonable maximum width lets you reduce unnecessary resolution while maintaining the original proportions. QuakeStar's shrink-only behavior also prevents a smaller source image from being enlarged unnecessarily.
Different image formats are suited to different kinds of content.
JPEG is widely used for photographs. It uses lossy compression, which can produce relatively small files by discarding some visual information.
PNG uses lossless compression and supports transparency. It is often a good choice for graphics, diagrams, interface elements and images where sharp edges are important. Photographic PNG files can be much larger than equivalent JPEG or WebP files.
WebP is designed for efficient web delivery and can provide very good image quality at relatively small file sizes. It is a strong option when the resulting image will primarily be used online.
For JPEG and WebP output, the quality setting controls the trade-off between visual fidelity and compression.
A higher quality setting generally preserves more detail and creates a larger file. A lower setting generally creates a smaller file but may introduce visible compression artifacts, particularly around fine details, text and high-contrast edges.
There is no single correct setting for every image. A photograph being displayed at modest dimensions on a webpage may tolerate considerably more compression than an image being prepared for archival or print use.
If your goal is simply to make a huge camera image suitable for a website or email, reducing its dimensions may provide a much larger benefit than aggressively reducing JPEG quality.
A photograph does not need to be 4,000 pixels wide if it will only ever be displayed at 1,000 pixels. For many everyday images, appropriate dimensions plus moderate compression produce a better result than keeping enormous dimensions and applying extreme compression.
Resizing permanently removes pixel information. If you resize a 4,000-pixel image to 800 pixels, the resulting copy no longer contains the original level of detail. Enlarging that 800-pixel copy later cannot recreate all of the information that was discarded.
Keep the original image if you may need the full-resolution version in the future.