Seamless pattern guide
How do you vectorize a raster pattern without changing its tile edges?
Keep the original tile rectangle as a clipping boundary, trace motifs without resizing that rectangle, and wrap every crossing path precisely.
Treat tracing and repetition as separate problems
Image tracing converts pixels into paths, but it does not understand which shapes must continue across opposite edges. Trace a high-quality raster with settings appropriate to the artwork, then inspect the expanded paths. Simplification, noise removal, and corner smoothing can alter boundary shapes even when the preview looks close.
Place a rectangle with the exact raster dimensions behind the artwork and do not scale it during cleanup. That rectangle is the repeat coordinate system. If you resize the traced artwork independently or fit the rectangle to new path bounds, crossing motifs will no longer land at the coordinates defined by the source.
Rebuild wrapped paths with exact translation
Any path touching the right boundary needs a duplicate translated left by exactly one tile width. A path touching the bottom needs a duplicate translated upward by exactly one tile height. Corner paths require both translations. Use numeric transforms rather than dragging and snapping by eye.
The clipping rectangle should have no fill and no stroke when used to define an Illustrator pattern swatch. Strokes centered on the boundary can extend beyond the tile and confuse measurements. Expand appearance only when necessary, and verify that the resulting paths still use the original coordinate system.
Compare vector and raster repeats
Create a multi-tile preview from the vector swatch and compare it with the original raster repeat at the same motif scale. Look for gaps, doubled paths, changed negative space, and colors dropped by tracing. A vector result can be technically seamless while deviating too far from the artwork to be a faithful conversion.
Export one raster proof from the final vector swatch and run it through the checker. This catches boundary errors that may be hard to see among selection outlines. Keep both masters: the raster remains the reference, while the vector version is useful only after it passes an independent repeat test.
