8 min read
Image tools guide
Understand which Lumli image tool to use and how to get a reliable result.
Compress images
Use Compress when the dimensions are acceptable but the file is too heavy for a website, email, upload form, or message. Lowering quality usually reduces size more than resizing alone; changing to WebP or AVIF can reduce it further where compatibility allows.
- Keep a copy of the original before aggressive compression.
- Check text, faces, gradients, and fine edges at 100% zoom.
- Choose JPEG/WebP/AVIF for photographic content and PNG when transparency or lossless detail matters.
Convert formats
Use Convert when a service, device, or workflow requires a different format. Conversion changes the container and encoding; it cannot recreate detail already lost in a low-quality source.
- HEIC to JPEG improves compatibility but can increase file size.
- PNG preserves transparency; JPEG does not.
- AVIF and WebP are efficient modern formats, but verify support in the destination application.
Resize and crop
Use Resize to create exact pixel dimensions, change aspect ratio, or crop for a destination such as a profile, thumbnail, presentation, or website. Lock the aspect ratio when you want to avoid stretching.
Prepare a passport or ID photo
Passport Photo combines document-specific dimensions with local face-position, resolution, exposure, sharpness, and background checks. Presets that require an original unaltered photo disable background replacement; authority-controlled workflows such as German passport and Personalausweis photos are checker-only.
Remove a background
Remove BG uses browser-side model inference to identify the main subject and produce a transparent result. Clear separation, good lighting, and visible edges improve the cutout. Hair, glass, motion blur, and similar foreground/background colors are harder cases.
Retouch an object
Retouch works best on small distractions surrounded by repeatable texture. Paint a mask slightly beyond the unwanted object, process it, and repeat with smaller passes if needed. Large foreground objects or complex geometry may require manual editing afterward.
Upscale an image
UltraScale enlarges and enhances an image but cannot guarantee authentic detail that was never captured. Start with the cleanest available source, avoid repeatedly upscaling the same output, and inspect faces, text, and patterns carefully.