Foto Master

Exporting the Final PMWall Mosaic

Updated Today · 3 min readIntermediate

The high-resolution mosaic is the main deliverable of a Photo Mosaic Wall event. PMWall stitches every placed tile into a single print-ready master image.

Exporting

  1. Open the Runtime tab.
  2. Click Export Hi-Res.
  3. When it finishes, click Open output folder.

The export runs from the tiles already saved on disk, so you do not need to keep the mosaic running to export it.

What You Get

A single LZW-compressed RGB TIFF, written to the Prints folder inside the event folder:

C:\PMWall\Events\{Event Name}\Prints\

The filename records the timestamp, the grid, and the tile size:

mosaic_master_20260818_143005_50x50_600x600.tif

TIFF with lossless compression is deliberate. This file is a print master, so it should not carry JPEG artefacts into large-format output.

What the Export Requires

PMWall exports only from a completely filled wall. Every cell has to contribute a tile, so:

  • Cells Left on the Runtime tab must be zero.
  • Every tile file must be present in the event's final folder.
  • Every tile must be the same pixel size.

If any of those is not true, PMWall tells you which one. See High-Resolution Mosaic Not Generating or Not Compiling Properly.

Never edit or delete anything inside the final folder for an event you still intend to export.

How Big the File Will Be

The master's pixel dimensions are simply the grid multiplied by the tile size:

width  = Columns x Cell output size
height = Rows    x Cell output size

A 50x50 grid at the default 600 px Cell output size produces a 30,000 x 30,000 pixel master. That is a large file, and the export needs both time and free disk space to build it.

To control the size, set Cell output size in the Cloud template before the event. At 300 DPI, 600 px is a 2 x 2 inch printed tile, which is the standard mosaic tile.

Tip: Decide the final print size before the event, not after. Grid and tile size are locked once the wall has tiles on it, so the export dimensions are effectively fixed the moment the event starts.

Print Resolution

The DPI written into the exported file comes from Settings > Printer > Resolution DPI, default 300. It is read at export time, so you can correct it and re-export without re-running the event.

DPI does not change the pixel dimensions. It tells the print house how large those pixels should be on paper.

Handing Off to a Print House

Send the TIFF along with:

  • The intended final print size
  • The grid, such as 50 columns x 50 rows
  • The DPI the file was exported at
  • Whether it prints as one piece or split into panels
  • Whether the print house should add bleed, crop marks, or mounting margins

Tell them not to rescale the file to fit a different size unless you have approved the new dimensions.

This export is the finished mosaic image. It is a different file from the Print Board PDF, which is the empty gridded board that physical tiles are stuck onto. See Creating a PMWall Print Board File for Your Print House.

After Exporting

Copy the export off the event computer before anything else. If Auto-delete event content is enabled under Settings > Storage, event folders are removed on a schedule, and that includes the Prints folder.

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