Photo to Stained Glass Pattern

Original, editable studies

Four subjects to simplify

Choose a finished study to load its working geometry. Change the piece count, inspect a shape, or export directly from the workshop.

From an idea to a numbered cutting pattern

1. Choose an example or upload a local image. Set the real panel size, then request 10–120 pieces and make the pattern. Begin with 24 pieces when comparing detail with cutting effort.
2. Select a numbered piece and read its dimensions. Review narrow widths and deep corners, merge only neighboring regions where useful, and compare the remaining risks after each repair.
3. Choose the construction heart, glass materials and print setup. Preview the tile grid, download a free file, and measure its printed ruler. Save the editable project before closing the tab.

Choose a photograph with a clear subject

A flower against a simple sky is easier to divide into 24 useful glass pieces than a flower against grass, fences and patterned clothing. Start with one recognizable outline and a few broad color groups. Tight framing gives the subject more of the available pieces. The tool supports local JPG, PNG, WEBP and safe SVG files up to 10 MB; it does not fetch remote photographs.

Images are decoded into browser memory and large images are reduced to a longest edge of 2,048 pixels for processing. The source is never attached to a production request. An empty file, mismatched image signature, active SVG or decoding failure produces an error. A source SVG is treated as a locally rasterized illustration for segmentation, rather than a promise to import arbitrary CAD paths or scripts.

Simplify the background without losing the flower

A 36-piece study can retain more small color changes, while a 24-piece version must spend its regions on the main silhouette. The partitioner divides the physical panel deterministically using color contrast and spatial extent. Background tone merging reduces differences between similar source colors before that division. Use the original view to check whether the petals, leaf, cat ears or lighthouse remain recognizable.

Simplification changes the partition choices rather than applying a transparent filter over the photograph. Every resulting region has an actual closed vector boundary and a unique label. Shared cut boundaries remain consistent because each split divides one existing polygon into two. If the subject loses its identity at 24 pieces, crop the source more tightly or increase the requested count; do not assume a large count automatically makes a better cutting plan.

Turn a color study into a cutting plan

Set the intended panel size before inspecting fragments. A pet portrait designed for 8 × 10 inches has a different physical minimum width from the same arrangement at 16 × 20 inches. Use 6–20 mm as a review threshold, and raise it toward 15 mm when you want to identify more narrow shapes. The actual result count may be lower when a split would make a region narrower than the threshold.

For local repairs, select two neighboring pieces and merge them. A narrow background fragment can often join a larger background area, whereas merging across a pet ear may damage recognition. Compare the new contour with the original and use Undo if the repair costs too much detail. The report keeps remaining deep corners visible instead of claiming that a photo conversion is automatically safe to score.

Centerlines, cutting lines and actual glass

A centerline cartoon describes how the panel fits together. A cutting contour describes the smaller piece of glass that fits beside the seam. Keep the two files clearly named in the workshop: tracing the centerline as a cut line would leave too little room for the chosen heart. The preview seam finish is cosmetic; black patina, copper and silver grey keep the same physical boundaries.

The material table integrates the compensated polygons, then groups their areas by glass ID. A 25% waste allowance multiplies the net area by 1.25; it does not turn irregular shapes into a guaranteed shopping list. Sheet nesting answers a different question by placing actual cutting contours inside a selected sheet, with a 5 mm edge margin and 3 mm gap by default. A piece that cannot fit is reported rather than silently omitted.

A project you can inspect and keep

Select any numbered shape to see its cut width, height and net area. The bounding dimensions help you find a blank large enough for that piece; net area measures its polygon, so a triangle is not counted as its full enclosing rectangle. The glass list is separate from the piece numbers: two blue pieces can have different IDs but use the same material.

Save a local .sgpattern.json project before leaving the page. There is no automatic browser draft or cloud gallery. Reopening the file restores the millimetre geometry, numbering, palette, material and cutting settings. An invalid project or failed image decode leaves the last valid pattern available. A maximum of 200 imported pieces and 512 vertices per piece keeps inspection and file generation bounded.

Match the file to the workshop task

For a small suncatcher, use the free single-layer inset SVG and the paper cartoon together. For a larger panel, keep the tiled PDF at actual scale. If you are preparing layered sticker dies, matching pieces to stock sheets, or selling teaching packs, the three workshop ZIPs provide those specific production documents.

Use the copper foil guide for the 0.8 mm heart and tape-width calculation, the lead came guide for 1.6–2.0 mm hearts and frame allowances, and the printing guide for measured 1:1 tiles.

Cutting difficulty and glass quantities are based on planar geometry and the selected waste allowance. Adjust the real cutting plan for glass texture, material and the tools you use.

More ways to start the same workshop