How a photo becomes a stencil
The tool converts the photo to grayscale and stretches its levels first, because most snapshots are duller than they look and a stencil lives on contrast. A median pass removes speckle. Then a threshold splits the tones: everything darker than the line is cut, everything lighter stays. The Detail slider moves that line.
Where the simple version stops, the carving-relevant part starts. Every shape made of holes is checked for pieces that would fall out, and each one gets a thin uncut bridge to the surrounding wall. Fragments too small to carve are removed. What is left is counted, and the piece count is what the difficulty rating is computed from.
Why three layers beat a silhouette
A traditional stencil is one bit: hole or no hole. On a pumpkin that means every lit shape screams at the same brightness, which is why so many carved pumpkins look like badges rather than pictures.
Real carved portraits use a third state. The pumpkin wall is scraped down to a few millimetres where the photo’s mid-tones are, and those areas glow dimly through the remaining flesh while the cut holes glow fully. The generator marks those areas grey on a second sheet. You need a spoon or a clay loop for them, and patience, but a face stops being a silhouette the moment it has shading.
Printing at pumpkin scale
The PDF is scaled so the design’s width equals the face width you enter, capped at what the sheet holds. A typical carving pumpkin has a usable face of roughly 15 to 25 cm across; if you enter more than the paper fits, the sheet prints at the maximum and says so at the bottom.
Tape the print onto the pumpkin with the design centred on the roundest part. Pin-prick every line, remove the sheet, and connect the dots by eye. The images to PDF tool is the neighbour worth knowing if your printer insists on scaling and you need control back.
Carving notes that save pumpkins
Cut the lid from the bottom. The stem stays attached to the piece you carve out as a handle, the candle sits flat on the base, and the opening is hidden. This is also how the viral carving videos do it, because it drains better.
Cut centres before edges: the sheet of pumpkin you are working stays rigid longer. Small details last, bridges very last, from inside. A hole that took a bridge to stay in place will hold until you decide otherwise.
Thin walls glow more. Scraping the inside of the pumpkin down to about 2 to 3 cm is standard practice before any detail work, which is another thing the grey layer benefits from.
More from the same photos: the Halloween hub’s from-your-photos section gathers this stencil, the costume-photo coloring pages and the boo basket kit in one place.
Questions
Do I cut the black or the white parts?
The black parts. On the printed stencil black means cut all the way through, grey means shave, and white stays as pumpkin skin. That matches how a finished jack-o'-lantern reads — the holes glow brightest, the scraped areas glow dimly, the skin barely glows at all.
Which photos make good stencils?
A dark, clearly outlined subject on a bright background. Faces work best facing the camera with even light; a backlit or flat grey photo gives the threshold little to work with. The Detail slider shifts the cut-off when the first result is too busy or too sparse.
What are the bridges the tool talks about?
Thin strips it leaves uncut between a loose piece and the surrounding pumpkin. An eye or a letter centre cut all the way around would fall inside and vanish. The tool finds those islands and connects each one with a bridge you can cut away last, from inside, if you want.
Why three layers instead of two?
A two-layer pattern is holes and skin, so every glowing area is full brightness. The third layer is scraped a few millimetres deep instead of cut, so light passes through the remaining wall dimly, which is what makes shaded portraits possible on a pumpkin.
How do I get the pattern onto the pumpkin?
Print the PDF, tape the sheet to the face, and prick along the lines with a pin, or slide transfer paper between sheet and skin and trace. Cut the lid from the bottom of the pumpkin rather than the top; the stem becomes a handle and the candle sits flat.
Is my photo uploaded anywhere?
No. The image is decoded, thresholded and printed entirely in your browser, and the PDF is assembled there too. Nothing is sent to a server, and no account is needed to download.