Painting with the whole screen
⛶ Fill the screen hides every control and gives the picture the entire display — around a third more image on a phone. A single faint button stays in the top corner to bring the controls back; Escape does the same on a keyboard. Where the browser also offers true fullscreen it is taken, and the rotation held, but the mode does not depend on either, so it works the same on an iPhone. ☀ keeps the screen awake, so it will not dim with a brush in your hand.
Is there a phone app?
This is it — add it to your home screen and it behaves like one. On iPhone, open this page in Safari, tap the Share button, choose Add to Home Screen, and confirm. Launch it from the new icon and it opens full screen with no address bar or browser buttons, keeps your image and settings between sessions, and works with no signal at all — useful outdoors, or anywhere your hands are wet and your data is not. On Android, choose Install app or Add to Home screen from the browser menu.
1. Frame your paper
Load a photograph, then open Crop from beneath the image in the Photo view, and enter your paper and square sizes. The whole photograph stays visible; drag the frame over it and pinch to resize it. Anything dimmed is being cropped away. The frame always matches your paper, and Swap portrait / landscape is right there if it is the wrong way round.
2. Choose what to study
Photo keeps detail. Colour finds broad wash families; place it over grayscale to see structure without competing colour, or over Paper to drop the photograph entirely and see the washes alone. The Paper and Image buttons beside Grid switch that while you work; tap Image twice to swap grayscale and colour. Notan reads value two ways: Value masses groups it into tones, and Light threshold gives one moving black-and-white split — drag that one from end to end to watch the light arrive. Contour finds the edges worth drawing with a pen once the paint is dry — its Detail slider is roughly how much of the picture becomes line, and tapping Contour again cycles Lines, a Sketch style that shades every edge by strength, and Plotter, which draws each edge as a single centreline. Plotter can add parallel Shadow hatching wherever Notan's shared Light reading is dark. Separate shadow areas receive internally consistent angles inferred from the visible light direction, with the shadow shape or a diagonal used when the cue is ambiguous. Use the SVG's separate Contour layer for the graphite guide, paint the watercolour, then re-register the sheet and plot only the Shading layer in ink. In Plotter, raise Straighten to even out nearly straight runs and Shortest to remove short marks. Tapping Notan again swaps its two readings the same way. Grid works over every view.
3. Isolate one wash
The palette strip shows Washes and Accents separately when a picture has both, and each swatch reports how much of the picture it covers. Tap a swatch to show only that colour; everything else falls back to the reference underneath, so you can see exactly where the wash belongs. Tap further swatches to add them — one green and one yellow together, nothing else — and tap any lit swatch to drop it again; turning the last one off brings the whole palette back. The first time you do this the reference switches to Paper, to show that the photograph can be taken away entirely; after that the ground stays wherever you leave it.
4. Mix a wash
Tap the image for a large sampled swatch. Colour mode samples the pure reduced colour. Photo mode averages a small area. Use it as a relative guide, then judge pigment on your paper.
5. Save a reference
Save any individual view, a 300-DPI reference sheet, or a layered plotter SVG. The SVG keeps its invisible registration frame, contour, and optional shadow hatching in separate layers. On iPhone, use the share sheet to save to Photos, Files, or print.
Grid convention
Columns read left-to-right and rows top-to-bottom. Partial cells appear at the top and right because the physical grid is ruled from the bottom-left.
Everything runs locally. Your photograph is never uploaded.