Image quality and compression
JPEG and WebP optimisation can use lossy compression, which changes some image information to reduce file size. We aim to preserve a good visual result, but no automatic setting can guarantee identical appearance for every photograph, screenshot, illustration or graphic.
Fine details, gradients, text, complex patterns and brand colours can respond differently to compression. Always inspect important images at the intended display size before using them.
File-size results and target sizes
Displayed savings are calculated from the selected original and generated output. Results depend on the source format, dimensions, existing compression and image content. No fixed percentage reduction is guaranteed.
A requested target size may not be achievable without lowering visual quality beyond a reasonable safeguard or reducing image dimensions. Where a safe target cannot be reached, the tool may provide the closest practical result instead.
Format conversion and transparency
Changing image format can affect file size, visual appearance, transparency and compatibility. JPEG does not support transparent backgrounds, so transparent artwork converted to JPEG requires a solid background or another suitable treatment.
PNG, WebP and SVG have different capabilities and are not interchangeable for every project. A converted output may be larger than the source where the selected format requires more image information.
SVG artwork and embedded information
SVG optimisation aims to preserve vector output while removing or rejecting unsafe active content, external references, unnecessary comments and some editor-generated information. Complex artwork, embedded resources, special fonts or advanced effects can behave differently after sanitisation or conversion.
Image processing may also remove, replace or change metadata, colour profiles, orientation information or other embedded properties depending on the source format and browser encoder. Keep a master copy of important design or brand assets.
Resizing, cropping and watermarking
Resizing changes image dimensions, and cropping permanently removes parts of the original composition from the generated output. Enlarging an image does not recreate genuine detail that was absent from the original file.
Watermark appearance depends on the image size, selected text or logo, opacity, position and background. Check placement, readability and branding before publishing or distributing the result.
Email image preparation
Email previews are practical preparation aids rather than a guarantee of identical rendering in every inbox. Outlook, Gmail, Apple Mail, Android applications and other email clients can display dimensions, backgrounds, dark-mode colours and image scaling differently.
Retina-ready dimensions can improve sharpness on high-density displays, but they can also increase file size. Image preparation alone cannot guarantee email deliverability, accessibility compliance, dark-mode compatibility, loading speed or campaign performance.
Social media specifications
Social media image dimensions, previews, safe areas and cropping behaviours are controlled by the relevant platform and may change without notice. Desktop and mobile displays can crop or position the same artwork differently.
Check important profile images, banners, posts and creative assets against the platform's current publishing interface before relying on a preset or guide.
Guides and third-party references
Our guides are provided for general practical information and do not constitute professional legal, marketing, accessibility or technical advice. Third-party documentation, product interfaces and platform recommendations may change after an article is published.
References to Google, Microsoft, Meta, Facebook, Instagram, LinkedIn, TikTok, Mailchimp, Salesforce, Oracle, HubSpot, Klaviyo or other brands do not imply official affiliation, endorsement or partnership.
Browser and device limitations
Processing performance depends on your browser, operating system, available memory, supported image formats and the size or number of selected files. Some features require modern browser capabilities and may not work identically on every device.
Keep your original files
Always retain a safe copy of your original image until you have opened, inspected and approved the downloaded output for its intended use. You remain responsible for checking copyright, permissions, technical suitability and final quality.
For further information, read our Terms of Use or contact info@imageoptimise.com.
Last reviewed: 23 August 2026