help

image

browse / drop

Load an image or video from your device — or drop it straight onto the render. Nothing is uploaded; all processing happens in your browser.

input thumbnail

Hold it down to peek at the input with the adjustments below applied.

crop / reposition

Zoom in on the interesting part by manipulating the input right on the render: drag to move it, scroll to zoom on the cursor (a trackpad pinch works too), alt/⌥ + scroll to rotate — on a touch screen, drag, pinch and twist with two fingers while one finger keeps scrolling the page. While you're reframing, the input shows with a composition grid and an accent border along its own edge — so you can see where it ends even on a white background; let go and the lines recompute for the new framing, which also carries into every export (a video keeps one framing across all its frames). Double-click the render — or the ⛶ full image chip that appears — to get the whole picture back.

brightness / contrast

Brighten or darken the image, and push contrast around mid grey, before segmentation.

gamma / key

Midtone curve — above 1 lifts the midtones, below 1 keys them down.

saturation

Uniform color saturation; 0 turns the input greyscale.

vibrance

Saturation boost weighted towards muted colors, so it won't blow out what's already vivid.

video

supported formats

Whatever your browser can decode — MP4 (H.264) and WebM play everywhere. HEVC (H.265) videos, like the .mov recordings phones make, don't decode in many browsers; the studio will tell you when that happens. Convert those to MP4 (H.264) first — QuickTime's export, HandBrake, or ffmpeg -i input.mov -c:v libx264 -pix_fmt yuv420p output.mp4 — and load the result.

output fps

Frame rate the video is sampled at — fewer frames per second means fewer, smaller files.

frames

The exported frame window (first – last). The timeline over the render shades this range; scrub it or step frame by frame to preview any moment with the current settings.

frame sequence export

Renders every frame in the window and downloads one zip — plottable SVGs, images (png, jpeg or webp with quality and scale controls), or both.

segmentation

Segmentation carves the image into regions of similar tone — the shapes the lines will fill.

algorithm

Watershed follows tonal basins, posterize bands intensities, k-means clusters them, and SLIC carves compact superpixels.

resolution

Grid resolution the image is sampled at — more cells, more detail, slower renders.

smoothing

Blur passes before segmentation — higher means fewer, larger regions.

superpixel size / compactness

SLIC only: superpixel spacing in grid cells, and how strictly they stay grid-like versus following image detail.

tolerance

Maximum intensity difference for merging adjacent regions.

min region size

Regions with fewer cells get absorbed into a neighbour.

lines

pen width (mm)

Physical line width used for rendering and spacing math. Layers can override it.

ink gamma

Perceptual weight on ink intensity before it becomes line spacing.

ink boost

Coverage multiplier — above 1 pushes dark regions into overlapping lines.

ink threshold

The band of ink a region must fall in to be hatched. The low bound is a high-pass filter — regions holding less ink stay empty; the high bound is a low-pass filter — regions holding more ink stay empty too (leave it at 1 to keep every dark region). Narrow the band from both ends to isolate the midtones.

spacing (mm)

Nominal min–max line spacing. Each region lands somewhere in this range based on its ink: dense lines where the image is dark, sparse where it's light.

hand-drawn lines

Swap the perfectly straight hatch lines for organic, hand-drawn-looking ones. Off by default — and off means untouched: the classic ruler-straight output stays exactly as it was. When on, the same wobble flows through everything consistently — preview, SVG and PNG exports, frame sequences and the plot-time estimate (squiggly lines are longer, so plots take a bit more time). The wobble is deterministic: the same settings always draw the same squiggles.

squiggle (mm)

How far a line may wander from perfectly straight — the squiggliness. Lines keep their exact endpoints and short strokes stay steadier, so regions keep their shape.

wave (mm)

Distance between direction changes along a line — short makes a nervous scribble, long makes lazy waves.

variation

Rerolls the wobble pattern without changing its character.

presets & randomize

randomize

The dice rolls all segmentation, lines and layer settings. "Stick to built-in presets" limits the roll to ink + pen combinations that physically exist, so the result stays plottable.

presets

Apply a built-in look, or save your current settings under a name — saved presets live in your browser. A fresh visit opens on a random built-in. Presets are about the look: your output width and margin stay yours (any values stored in older preset files are ignored).

export / import .json

Move settings between browsers or share them as a small JSON file.

layers — one per pen

layer basics

Each layer is one pen: pick its color, name it, toggle it, reorder with ▲▼ (layers draw top to bottom). The name becomes the layer label in the exported SVG.

channel

Which part of the image drives the layer's ink: cyan / magenta / yellow (the print channels), key / darkness, red / green / blue, or (inverted) luminance. "Match pen color" instead derives the channel from the layer's pen color.

angle min / max

Hatch direction range — every region picks its own angle within it, based on the region's shape, so one layer never looks mechanical.

overrides

Pen width, the threshold band (low / high), spacing, ink gamma and ink boost can be set per layer. Empty fields inherit the global lines values (shown as grey italics); "clear overrides" resets them all.

export

width (mm)

Physical output width — the height follows the image aspect. This is your own setting: presets and the dice never touch it, and it stays put while you switch inputs.

output format

Optionally compose onto a fixed sheet instead. Toggle A6–A3 (tap again to turn off — at most one is active), or pick more sizes from the list: A2–A0, B-series, US letter/legal/ tabloid, squares, AxiDraw beds and a custom width × height. The render takes the page's shape, the export becomes exactly that page, and the whole image starts fitted inside the margins — from there, crop and reposition it into the sheet with the usual gestures. Named sheets are turned to match the input (flip them with ⇄); a new input starts back at no format.

margin (mm)

With a format active, the margin is a mask: a band this wide around the sheet's edge is kept clear of ink, whatever the composition puts there — like a matted print, and safe for the plotter's paper clamps. The reframing view dims the masked band while you compose. Defaults to 10mm; 0 disables the mask.

↓ SVG

A plottable SVG with one layer group per pen, ready for plotter software.

↓ PNG

The current render as an image — for screens, sharing and regular printing.

⚡ order this plot

No plotter? I'll plot it for you — real pens on paper, shipped flat-packed with tracking, shipping included in the price. Orders are limited to the inks in the built-in presets and sizes up to A3; the order dialog tells you if a design needs adjusting. Only the exported SVG — the lines to draw — is sent with your order, never your image, and it's used solely to produce your plot.

stats & plot time

grid / regions / lines / render

The sampling grid size, how many tonal regions segmentation found, how many hatch lines were drawn, and how long your browser needed to compute the render.

plot time

Estimated plotting time on an AxiDraw-style machine (saxi's motion model): drawing, travel and pen lifts — hover it for the per-pen breakdown.

plotter settings

The motion profile behind that estimate: pen-up/-down speeds and accelerations, cornering, pen lift/drop pauses and the join radius (lines closer than this are drawn without lifting the pen). Match it to your machine, or reset to saxi's defaults.

prep — /prep

The plot prep tool takes an exported SVG and dresses it for the machine.

output page

Pick the page size and orientation the plotter will see; drag the artwork (or use the offsets) to place it.

multiple SVGs

Drop several same-size SVGs, a folder, or the studio's frame-sequence zip (SVGs in the root or an svg/ subfolder) — geared to the video export. Frames are laid out as a grid with an adjustable per-frame margin, gap and edge clearance, across as many pages as needed. Matching layers of all frames are combined so pen selection in saxi stays simple, and each frame carries its number in plottable single-stroke digits. Export downloads a zip with one page SVG per sheet.

paper outline

Marks where to place the physical paper — sized to the artwork (or each frame) or a fixed format, plus margin, drawn as a full rectangle, corner marks or crosses.

calibration markers

Rulers, a verify circle and one line pair per pen, so multi-pen plots line up. Drag the block anywhere.

page boundary

A rectangle around the full output page.

add reversed layers

Duplicates every artwork layer with the same lines running in the opposite direction — each line gets plotted twice for denser ink. Works on the studio's hand-drawn wobbly lines too: every squiggle is retraced point for point, just backwards.

export SVG

Downloads the decorated SVG with everything on its own (Inkscape-compatible) layer.

classic — /classic

The original RSTR, kept around for nostalgia (and because it still makes nice plots). One image, one layer, multiple pens. The algorithm that started it all.

good to know

private by design

Images, videos and settings never leave your device. The one deliberate exception: ordering a plot sends the exported SVG — the drawn lines, never your image — along with your order, and it's used solely to produce that plot.

works offline

RSTR is an installable web app — once visited, it keeps working without a connection.

settings persistence

Your settings are remembered in this browser from the moment you first edit them — until then, every visit rolls a fresh random preset.

real ink colors

The palettes behind the randomize button are sampled from real fountain-pen inks, so a random roll always lands on colors you can actually plot with. They're based on the ranges from De Atramentis, Octopus Fluids and Rohrer & Klingner.