Image Processing Methods & Limits

Supported inputs and safety limits

MB means 1,000,000 bytes. GIF, HEIC, SVG and animated PNG/WebP are not supported. Image headers are checked before decoding; malformed or unusually structured images may be rejected. These limits reduce memory pressure but cannot guarantee stability on every device.

Resize and crop method

Fit uses the smaller width/height scale factor inside the margin area. A 5% margin reserves 5% of each canvas dimension on each corresponding edge. Fill uses the larger factor to cover the canvas, clips overflow and uses the selected crop position. Both preserve source proportions.

Enlargement is off by default. Scale is capped at 1 when it is off; small sources can therefore leave background even in Fill mode. Margin is ignored in Fill mode. Every output is filled with the chosen background before drawing the image, so alpha transparency is not preserved.

Decoding and encoding

The browser decodes images using its image bitmap API with source orientation. The tool does not manually rotate EXIF-tagged photos a second time. Images are processed one at a time, and temporary full-size canvases are released after use. List previews are small thumbnails.

JPG and WebP use the quality setting as an encoder hint; PNG ignores it. Exact bytes, colors and interpolation can vary between browsers. The actual encoded MIME type determines the file extension. If WebP is unsupported and PNG is returned, a fallback notice is shown.

Preview and download meaning

The three crop previews are centered 1:1, 4:3 and 3:4 crops of the prepared output. They do not alter the output and do not reproduce any specific marketplace layout. ZIP stores successful outputs without additional compression. Failed inputs are listed and can leave sequence-number gaps.

Not an archival or color-proofing tool

Exports are newly encoded images. The original metadata container is not copied. Do not rely on this workflow to preserve EXIF/IPTC metadata, ICC profiles or exact color appearance. It is not a certified metadata eraser either. Keep originals separately and inspect downloaded files before publishing.

Verification scope

The project includes automated checks for resize geometry, naming, setting validation, image headers, generated routes, metadata and local links. These are not a claim of certification across every device or marketplace. Report reproducible errors with the settings and browser, without attaching private product images.

Technical references: image decoding, canvas encoding, ZIP library.