What a board is
A board is a rectangle of pixels with a physical size attached to it. The one that opens here is 3,600 by 5,400 pixels, which is twelve inches by eighteen at 300 dots per inch — a size you can hand to any print shop without a conversation. Everything you put on it is measured in those same pixels, so zooming out to see the whole thing changes what you are looking at and nothing about what gets saved.
Each photograph you add becomes a frame: a position, a size, an angle, an opacity, a crop window onto the original, and a place in the stack. Frames overlap, and which one wins is something you decide rather than something the order of your folder decides for you. Nothing is attached to anything else and nothing reflows when you move a neighbour.
| Paper | At 300 DPI | At 200 DPI |
|---|---|---|
| 8 × 10 in | 2,400 × 3,000 | 1,600 × 2,000 |
| 12 × 18 in | 3,600 × 5,400 | 2,400 × 3,600 |
| A3 — 29.7 × 42 cm | 3,508 × 4,961 | 2,339 × 3,307 |
| 18 × 24 in | 5,400 × 7,200 | 3,600 × 4,800 |
| 24 × 36 in | 7,200 × 10,800 | 4,800 × 7,200 |
Working order
There is no sequence you have to follow, but there is one that saves time, and it starts with the board rather than the photographs. Set the size first: a frame you positioned on a square board will be in a different place on a tall one, and changing the board afterwards means doing the arrangement twice.
- Size the board. Paper size, or width and height in inches, centimetres or pixels, with the dots per inch beside them. Changing the DPI keeps the paper and moves the pixels, which is the way round that matches what a printer will ask you.
- Read the photographs in. Drag a folder onto the board, use the picker, or paste one. They land as they decode, so the third can be moved while the ninetieth is still being read.
- Block in the big ones. Two or three photographs at a decent size, placed where you want the eye to go, before the other forty arrive to fill the gaps. A board built the other way round tends to end up evenly boring.
- Straighten, or deliberately do not. Snapping pulls edges and centres into line; the rotation arm above a selected frame is free by default and steps in fifteens with Shift held. Six frames at four degrees reads as a scatter. Six at four, nine, two, eleven, three and seven reads as an accident.
- Export at the size on the readout. The line above the button gives pixels, paper size, DPI and a rough file size before you commit to it.
A hundred steps of undo cover all of it — placement, depth, imports, deletions and a grid run, which collapses to a single step however many cells it filled.
What it will open
JPG, PNG, WebP and GIF work in every browser. TIFF, BMP and ICO work in nearly all of them. HEIC — what an iPhone shoots unless it has been told otherwise — works through a decoder fetched the first time one appears, so a board that never sees one never downloads it. Up to 120 MB a file.
Some things are put right on the way in, and the tray says so under the thumbnail when they are. A sideways phone photograph is turned upright from the tag the camera wrote, checked against the browser first so it is never turned twice. A CMYK scan is converted approximately, which is fine for judging an arrangement and is not colour management — the print shop’s software is where that belongs. An animated GIF contributes its first frame. A wide-gamut photograph becomes sRGB and looks a shade flatter here than in the phone gallery. A file that will not open is named on its own and the rest of the folder carries on.
Past about thirty-two megapixels on a desktop, or sixteen on an iPhone, a photograph is offered as a lighter working copy rather than refused — on a board this size the difference never reaches the paper. Past a hundred megapixels on a desktop, or forty on an iPhone, the answer is no, and the refusal carries the number with it.
What comes off the board
An export is one flat image. Every frame is drawn in its stack order onto the board’s own pixel grid, at the full size on the readout, and nothing about the arrangement survives in the file — a photograph you buried under three others is buried for good, and the way back is the board itself rather than the export. That is why the arrangement is kept separately and the export is treated as a delivery.
Two formats come out of it, and choosing between them is a question about size rather than about quality. PNG writes every pixel exactly as drawn and charges you in megabytes for the exactness. JPEG discards the detail eyes are worst at and lands somewhere around a fifth of the weight, which matters the moment an upload form or an email has an opinion.
| File | Roughly | Worth using when |
|---|---|---|
| PNG | 40–80 MB | A print shop, an archive, anything going back on a board later |
| JPEG at 92 | 6–12 MB | An upload that refuses the PNG, with nothing visible given up |
| JPEG at 75 | 2–4 MB | A screen, a message, a proof — never paper |
The writing happens in horizontal bands rather than in one pass, which is the only reason a board of this size finishes at all on a phone: the whole canvas is never held in memory at once. A large export takes tens of seconds and says so while it works. Getting one down to a specific number of kilobytes is a separate job with separate tools, and this board does not pretend to do it.
This board holds two hundred photos. It is not a page-layout program. No text boxes, no shape tools, no trim marks beyond one margin guide. If the poster needs type, set it where you print it.
And the arrangement is what survives a reload, not the pictures. Nothing you place here is stored as pixels anywhere, so a board reopened tomorrow comes back as a set of named outlines waiting to be pointed at the same files. That is the cost of not keeping copies of your photographs, and it is the right way round.
Asked and answered
How many photographs will one board actually take?
Two hundred is the number the memory budget was drawn for, and the reason it is plausible is that the board never holds two hundred full-size decodes at once: each photograph is kept as a 256-pixel tray thumbnail and a 1,600-pixel screen copy, and the file itself is opened again only at export. Nothing refuses you past two hundred. How it feels at that count depends on the machine you are on, and the export is the part that slows first, because every original is read again at full size.
What size board do I need for a 24 by 36 inch print?
24 × 36 inches at 300 dots per inch is 7,200 × 10,800 pixels, which is a large but ordinary board here. At 200 DPI it is 4,800 × 7,200, and at the distance a poster that size is looked at, 200 is honestly hard to tell from 300. The size panel does the arithmetic both ways: change the DPI and the paper size stays put while the pixel count moves.
Can I make the photographs sit in exact rows?
Yes, two ways. The grid panel takes rows, columns, a gap and an edge margin and fills the cells in tray order — and what comes out is a set of ordinary frames, not a locked arrangement, so you can pull one out and leave the hole. Or turn on snapping and place them by hand: edges, centres and the board's own middle all pull at six screen pixels, which stays six screen pixels however far you zoom.
My phone photographs are HEIC. Will they open?
They will. A decoder for HEIC is fetched the first time one turns up and never before, so a board of JPEGs does not pay for it. Everything else a camera or a scanner produces opens too — JPG, PNG, WebP and GIF everywhere, TIFF, BMP and ICO nearly everywhere.
Why is a photograph on my board slightly soft?
Because the screen copy is capped at 1,600 pixels on the long edge and you have scaled that frame up past what it holds. It is a display decision, not a document one: the export reads the original file again at full size, so a frame that looks soft at 400 per cent on screen will be sharp in the file you save.
Does the board survive closing the tab?
The arrangement does. Board size, every frame's position, angle, crop and depth, and the name and pixel size of the photograph each one belongs to are written to this browser's own storage. The photographs themselves are not written anywhere, so a restored board comes back as named outlines and you point it at the same files to fill them in again.