Nature Figure Preparation Guide

Overview

Resolution Requirements

Verify Resolution with 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

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

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

Python: Set Figure Dimensions

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

# 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

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

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

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

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

Key Concepts

Resolution and DPI

Vector vs Raster Formats

Image Integrity

Decision Framework

What type of figure are you preparing?
├── Graph, schematic, or diagram → Vector format (AI, EPS, PDF)
│   ├── Created in Illustrator → Export as AI or EPS
│   └── Created in Python/R → Export as PDF or EPS
├── Photograph or micrograph → Raster format (TIFF, PSD, JPEG)
│   ├── Need highest quality → TIFF at 450+ DPI
│   └── File size constrained → JPEG at 300+ DPI
└── Multi-panel composite → Single assembled file
    ├── Mixed vector + raster → Assemble in Illustrator, export as AI/PDF
    └── All raster panels → Assemble in Photoshop, export as TIFF

Best Practices

1. Export at native resolution: Always capture or generate images at the target resolution (300+ DPI). Never upsample low-resolution images in Photoshop or similar tools
2. Use colorblind-friendly palettes: Nature strongly recommends accessible color schemes. Avoid red-green combinations; use blue-orange or include pattern/shape differentiation
3. Keep text editable in vector files: Do not outline or rasterize text in AI/EPS files. Nature's production team may need to edit fonts during typesetting
4. Assemble multi-panel figures before upload: Combine all panels (a, b, c, etc.) into a single image file. Individual panel uploads will be rejected
5. Maintain separate layers for scale bars: Scale bars must remain on a separate layer from the image data so they can be repositioned during production
6. Apply adjustments uniformly: Any brightness, contrast, or color correction must be applied to the entire image, not selectively to specific regions
7. Retain original unprocessed data: Editors or reviewers may request raw image files at any stage of review or post-publication

Common Pitfalls

1. Upsampling low-resolution images: Artificially increasing DPI in image software does not add real detail and introduces blurring artifacts
   • How to avoid: Re-export from the original source (microscope, plotting software) at 300+ DPI natively
2. Submitting individual panels instead of assembled figures: Nature requires multi-panel figures as a single composite file
   • How to avoid: Assemble all panels in Illustrator or Photoshop before uploading; use lowercase bold labels (a, b, c)
3. Using uppercase panel labels: Nature uses lowercase bold (a, b, c), unlike many other journals that use uppercase
   • How to avoid: Double-check the journal's labeling convention; Nature specifically requires lowercase
4. Outlining text in vector files: Converting text to outlines makes it uneditable, which Nature prohibits
   • How to avoid: Embed fonts as TrueType 2 or 42 instead of converting to outlines
5. Submitting in CMYK color mode: While accepted, CMYK narrows the color gamut and may misrepresent fluorescence data online
   • How to avoid: Submit in RGB; Nature handles CMYK conversion for print internally
6. Exceeding the 10 MB file size limit: Large TIFF files often exceed this threshold
   • How to avoid: Use LZW compression for TIFF files or convert to high-quality JPEG (300+ DPI)

Pre-Submission Checklist

• 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/