GitHub - 0plus1/oneyear: Python, memory optimised 365 square grid of photos

oneyear — A0 Square Photo Collage Generator

Generate a print-quality square mega-poster collage (e.g. “365 photos”) with:

EXIF-date sorting (DateTimeOriginal → DateTime → mtime fallback)
A configurable grid with white gutters around each photo
A configurable center title box (title + subtitle)
A fast preview mode (scaled output) for quick iteration
Print-friendly output (TIFF recommended)

Built in Python with Pillow. Managed strictly with uv.

Requirements

Python 3.10+ recommended
uv
libheif (if HEIF format is needed)

Install

Usage

The tool generates a square, print-quality mega-poster collage from a folder of photos (including HEIC), sorted by EXIF date and arranged in a grid with white gutters and a configurable center title box.

Basic command

uv run python main.py \
  --input "./in" \
  --output "./out/megaposter.tif"

Required arguments

--input
Folder containing source images. Scanned recursively.
Supported formats: JPG, JPEG, PNG, TIFF, WEBP, HEIC / HEIF.
--output
Output file path. The file extension determines the format:
.tif / .tiff (recommended for print), .png, .jpg.

Canvas & print settings

--dpi (default: 300)
Target DPI used to convert millimeters to pixels.
--square-mm (default: 841)
Size of the square canvas in millimeters.
841 corresponds to the short side of A0, allowing the square to be cut from an A0 sheet.
Use 1189 for an A0 long-side square (significantly larger).
--preview-scale (default: 1.0)
Scales the entire render for faster previews without changing layout.
Typical preview values: 0.1 – 0.2.

Grid & layout

--rows (default: auto)
Number of grid rows. If omitted, chosen automatically.
--cols (default: auto)
Number of grid columns. If omitted, chosen automatically.
--gutter (default: 10)
White gutter in pixels around each photo inside its grid cell.
--outer-margin (default: 80)
White margin in pixels around the entire grid.

Center title box

The center title box occupies a rectangular area measured in grid cells, reserved in the middle of the layout.

--center-box-h (default: 5)
Height of the center box in grid cells.
--center-box-w (default: 7)
Width of the center box in grid cells.
--box-bg (default: white)
Background color of the center box.
--text-padding (default: 80)
Padding in pixels inside the center box.
--no-text
Skip rendering title/subtitle and leave an empty center box (useful for external editing).

Text & typography

--title (default: "2025")
Main title text rendered in the center box.
--subtitle (default: "A year in photos")
Subtitle text rendered below the title.
--font (default: system font)
Path to a .ttf font file. If omitted, a system font is used.
--title-size (default: 220)
Font size in pixels for the title at full resolution.
--subtitle-size (default: 90)
Font size in pixels for the subtitle at full resolution.
--title-color (default: #111111)
Color of the title text.
--subtitle-color (default: #333333)
Color of the subtitle text.

Font sizes and padding are automatically scaled when using --preview-scale.

Examples

Fast preview (recommended while tuning layout)

uv run python main.py \
  --input "./in" \
  --output "./out/preview.png" \
  --preview-scale 0.15 \
  --title "2025" \
  --subtitle "Our year in 365 moments"

Full-resolution A0-square print master (TIFF)

uv run python main.py \
  --input "./in" \
  --output "./out/megaposter_a0square_300dpi.tif" \
  --title "2025" \
  --subtitle "Our year in 365 moments"

Custom font and colors

uv run python main.py \
  --input "./in" \
  --output "./out/megaposter.tif" \
  --font "./fonts/YourFont.ttf" \
  --title-color "#0B0B0B" \
  --subtitle-color "#444444"

Notes

Photos are sorted by EXIF DateTimeOriginal, then DateTime, with file modification time as fallback.
Images are center-cropped to fill their grid cells (no letterboxing).
The 7x5 default gives a perfect 365 photo grid; adjust these parameters and photo count to explore custom layouts.
TIFF output is recommended for professional printing.
Very large sizes (e.g. A0 long-side square at 300 DPI) may require significant RAM — use --preview-scale to iterate safely.

TODO

Face detection / subject-aware cropping
CMYK workflows (most printers accept sRGB TIFF)
Tiled rendering (quadrants) for ultra-large canvases
Optional date labels per tile
Optional “header band” instead of center box
Optional randomization within each month
“Polaroid” style borders or rounded corners