---
name: nature-figure-guide
description: "Figure and image preparation guide for Nature journal. Covers resolution (300+ DPI), file formats (AI, EPS, TIFF), RGB color mode, Helvetica/Arial fonts, lowercase panel labels, and image integrity requirements."
license: CC-BY-4.0
compatibility: Python 3.10+, Pillow, Matplotlib
metadata:
  authors: HITS
  version: "1.0"
---

# Nature Figure Preparation Guide

## Overview

This guide provides the complete specifications for preparing figures for submission to **Nature** and Nature Research journals. Following these guidelines ensures smooth processing and high-quality reproduction of your figures in both print and online formats.

**Official reference**: https://www.nature.com/nature/for-authors/formatting-guide

---

## Resolution Requirements

| Image Type | Minimum Resolution | Notes |
|---|---|---|
| All figures | 300 DPI | At maximum print size |
| Optimal quality | 450 DPI+ | Recommended for best online display |
| Online submission | 300 PPI max | To keep file sizes manageable |

**CRITICAL**: Do NOT artificially increase resolution (upsampling) in image editing software. This does not improve quality and may introduce artifacts.

### Verify Resolution with Python

```python
from PIL import Image

def check_nature_resolution(image_path):
    """Check if image meets Nature's resolution requirements."""
    img = Image.open(image_path)
    width_px, height_px = img.size
    dpi = img.info.get('dpi', (72, 72))

    print(f"Image: {image_path}")
    print(f"Dimensions: {width_px} x {height_px} px")
    print(f"DPI: {dpi[0]} x {dpi[1]}")

    if dpi[0] < 300 or dpi[1] < 300:
        print("WARNING: Resolution below 300 DPI minimum")
        print(f"  Need at least 300 DPI for Nature submission")
    elif dpi[0] >= 450:
        print("PASS: Meets optimal resolution (450+ DPI)")
    else:
        print("PASS: Meets minimum resolution (300+ DPI)")

    # Check file size
    import os
    size_mb = os.path.getsize(image_path) / (1024 * 1024)
    print(f"File size: {size_mb:.1f} MB")
    if size_mb > 10:
        print("WARNING: File exceeds 10 MB limit")

    return dpi[0] >= 300 and dpi[1] >= 300
```

---

## File Format

### Preferred Formats by Figure Type

| Figure Type | Preferred Format | Alternative |
|---|---|---|
| Line drawings, graphs, schematics | Adobe Illustrator (AI), EPS, PDF | Vector formats preserve editability |
| Photographs, micrographs | Photoshop (PSD), TIFF | High-quality raster |
| General purpose | JPEG (300-600 DPI) | Acceptable for most figures |
| Extended Data figures | JPEG (preferred), TIFF, EPS | |

### Also Accepted
- CorelDraw (up to version 8)
- Microsoft Word, Excel, PowerPoint

### File Size
- **Maximum**: 10 MB per figure file
- Most files should be well under this limit

### Important Rules
- Multi-panel figures must be assembled into a **single image file**
- Individual panels must NOT be uploaded separately
- Each complete figure must be a separate file upload

---

## Figure Size and Dimensions

Nature does not specify fixed column widths for initial submission, but figures should be:

- Composed as a **single image** for multi-panel figures
- Sized appropriately for the intended display
- **Not** uploaded as individual panels

### Python: Set Figure Dimensions

```python
import matplotlib.pyplot as plt

def create_nature_figure(n_panels=1, fig_type='single_column'):
    """Create a Matplotlib figure sized for Nature."""
    if fig_type == 'single_column':
        fig_width = 3.5  # inches (approx 89 mm)
    elif fig_type == 'double_column':
        fig_width = 7.0  # inches (approx 178 mm)
    else:
        fig_width = 5.0  # 1.5 column

    fig_height = fig_width * 0.75  # default aspect ratio

    fig, axes = plt.subplots(1, n_panels, figsize=(fig_width, fig_height))
    fig.set_dpi(450)

    return fig, axes
```

---

## Color Mode

- **RGB recommended** (wider color gamut; faithful reproduction of fluorescent colors online)
- CMYK also accepted (converted for print automatically)
- **Accessibility**: Use colorblind-friendly palettes

### Recommended Colorblind-Safe Palette

```python
# Nature-friendly colorblind-safe colors
NATURE_COLORS = {
    'blue':   '#0072B2',
    'orange': '#E69F00',
    'green':  '#009E73',
    'red':    '#D55E00',
    'purple': '#CC79A7',
    'cyan':   '#56B4E9',
    'yellow': '#F0E442',
    'black':  '#000000',
}
```

---

## Font Requirements

| Element | Font | Size | Style |
|---|---|---|---|
| Body text in figures | Helvetica or Arial | 5-7 pt | Regular |
| Panel labels | Helvetica or Arial | 8 pt | **Bold, lowercase** (a, b, c) |
| Amino acid sequences | Courier | — | Monospace |
| Greek characters | Symbol | — | — |

### Critical Rules
- Use **sans-serif** fonts only (Helvetica or Arial)
- **Do NOT outline text** — text must remain editable
- Embed fonts as TrueType 2 or 42 (NOT TrueType 3)
- Panel labels: **lowercase bold letters** (a, b, c — not A, B, C)

### Python: Apply Nature Font Settings

```python
import matplotlib.pyplot as plt

def set_nature_fonts():
    """Configure Matplotlib for Nature figure fonts."""
    plt.rcParams.update({
        'font.family': 'sans-serif',
        'font.sans-serif': ['Helvetica', 'Arial'],
        'font.size': 7,
        'axes.labelsize': 7,
        'axes.titlesize': 7,
        'xtick.labelsize': 6,
        'ytick.labelsize': 6,
        'legend.fontsize': 6,
        'figure.titlesize': 8,
    })
```

---

## Labeling Conventions

### Figure Numbering
- Sequential: Figure 1, Figure 2, Figure 3, etc.
- All figures must be cited in the text in order

### Panel Labels
- **Lowercase bold letters**: a, b, c, d, ...
- Font size: **8 pt bold**
- Position: top-left corner of each panel

### Axes and Legends
- Include **units in parentheses** on all axes
- Scale bars must be on **separate layers** (not flattened into the image)
- Figure legends placed on a separate manuscript page after References

### Example Panel Labeling

```python
import matplotlib.pyplot as plt
import string

def add_nature_panel_labels(fig, axes):
    """Add Nature-style lowercase bold panel labels."""
    if not hasattr(axes, '__iter__'):
        axes = [axes]

    for i, ax in enumerate(axes):
        label = string.ascii_lowercase[i]
        ax.text(-0.1, 1.1, label,
                transform=ax.transAxes,
                fontsize=8,
                fontweight='bold',
                va='top',
                ha='right',
                fontfamily='Arial')
```

---

## Image Integrity and Manipulation Policy

### Prohibited
- Flattening scale bars into the image layer
- Outlining text (must remain editable)
- Adding gridlines, patterns, or drop shadows
- Using colored text in graphs
- Publishing copyrighted images without permission

### Permitted (with transparency)
- Linear brightness/contrast adjustments applied **uniformly to the entire image**
- Color balance corrections applied to the **whole image**

### Best Practices
- Keep scale bars on separate layers for editability
- Avoid busy backgrounds behind text
- Remove superfluous decorative elements
- Obtain permissions for all copyrighted figures

---

## Python Quick Start: Full Validation

```python
from PIL import Image
import os

def validate_nature_figure(image_path):
    """Full validation of a figure against Nature requirements."""
    img = Image.open(image_path)
    issues = []

    # 1. Resolution check
    dpi = img.info.get('dpi', (72, 72))
    if dpi[0] < 300 or dpi[1] < 300:
        issues.append(f"Resolution too low: {dpi[0]}x{dpi[1]} DPI (need 300+)")

    # 2. Color mode check
    if img.mode == 'CMYK':
        issues.append("Color mode is CMYK; RGB is recommended for Nature")
    elif img.mode not in ('RGB', 'RGBA'):
        issues.append(f"Unexpected color mode: {img.mode}; use RGB")

    # 3. File size check
    size_mb = os.path.getsize(image_path) / (1024 * 1024)
    if size_mb > 10:
        issues.append(f"File size {size_mb:.1f} MB exceeds 10 MB limit")

    # 4. Format check
    fmt = img.format
    accepted = ['TIFF', 'JPEG', 'PNG', 'EPS', 'PDF']
    if fmt and fmt.upper() not in accepted:
        issues.append(f"Format '{fmt}' may not be accepted; prefer TIFF or JPEG")

    # Report
    print(f"=== Nature Figure Validation: {os.path.basename(image_path)} ===")
    print(f"Dimensions: {img.size[0]} x {img.size[1]} px")
    print(f"DPI: {dpi[0]} x {dpi[1]}")
    print(f"Color mode: {img.mode}")
    print(f"Format: {fmt}")
    print(f"File size: {size_mb:.1f} MB")

    if issues:
        print(f"\nISSUES FOUND ({len(issues)}):")
        for issue in issues:
            print(f"  - {issue}")
    else:
        print("\nAll checks PASSED")

    return len(issues) == 0
```

---

## Pre-Submission Checklist

Before submitting figures to Nature, verify:

- [ ] Resolution is at least 300 DPI (450+ DPI preferred)
- [ ] File format is AI, EPS, TIFF, PSD, or high-quality JPEG
- [ ] Each file is under 10 MB
- [ ] Multi-panel figures assembled as a single image file
- [ ] Color mode is RGB (not CMYK)
- [ ] Colorblind-accessible palette used
- [ ] Fonts are Helvetica or Arial, 5-7 pt body, 8 pt bold panel labels
- [ ] Panel labels are lowercase bold (a, b, c)
- [ ] Text is NOT outlined (remains editable)
- [ ] Fonts embedded as TrueType 2 or 42
- [ ] Scale bars on separate layers (not flattened)
- [ ] No gridlines, patterns, or drop shadows
- [ ] Axes include units in parentheses
- [ ] All image adjustments applied uniformly to entire image
- [ ] Original unprocessed data retained for editor/reviewer requests
- [ ] Copyright permissions obtained for any third-party images

---

## References

- Nature Formatting Guide: https://www.nature.com/nature/for-authors/formatting-guide
- Nature Final Submission: https://www.nature.com/nature/for-authors/final-submission
- Nature Research Figure Guide: https://research-figure-guide.nature.com/figures/preparing-figures-our-specifications/