出版用グラフィックのレンダリング

Produce publication-ready graphics that meet technical requirements for academic journals, books, presentations, and web publication. Covers DPI requirements, color space management, typography best practices, file format selection, and metadata embedding.

使用タイミング

• Preparing figures for academic journal submission
• Creating graphics for print publications (books, magazines)
• Generating high-quality assets for presentations
• Exporting visualizations for web publication with proper optimization
• Ensuring graphics meet publisher technical specifications
• Archiving graphics with proper metadata
• Creating multi-format exports from single source

入力

手順

1. Determine Output Requirements

Identify technical specifications for target publication:

# Common publication requirements

academic_journal:
  dpi: 300-600
  format: TIFF, EPS, PDF
  color_space: RGB or CMYK (check guidelines)
  max_width: 180mm (single column) or 390mm (double column)
  fonts: Embed or outline
  resolution_minimums:
    line_art: 1000 DPI
    halftone: 300 DPI
    combination: 600 DPI

web_publication:
  dpi: 72-96 (retina: 144-192)
  format: PNG, WebP, SVG
  color_space: sRGB
  max_file_size: 200KB-500KB
  optimization: Compress, progressive loading

presentation:
  dpi: 96-150
  format: PNG, PDF, SVG
  color_space: RGB
  dimensions: 16:9 or 4:3 aspect ratio
  contrast: High contrast for projectors

print_book:
  dpi: 300-600
  format: TIFF, PDF/X
  color_space: CMYK
  bleed: 3-5mm beyond trim
  fonts: Embedded

期待結果: Clear understanding of target requirements 失敗時: Contact publisher for specific guidelines, use conservative defaults

2. Set Correct DPI for Raster Graphics

Configure resolution based on output medium:

from PIL import Image

def set_dpi_pillow(image_path, output_path, target_dpi=300):
    """Set DPI metadata for PNG/TIFF."""
    img = Image.open(image_path)

    # Save with DPI metadata
    img.save(output_path, dpi=(target_dpi, target_dpi))
    print(f"Saved with {target_dpi} DPI: {output_path}")

def calculate_dimensions(width_mm, height_mm, dpi=300):
    """Calculate pixel dimensions from physical size."""
    # Convert mm to inches
    width_inches = width_mm / 25.4
    height_inches = height_mm / 25.4

    # Calculate pixels
    width_px = int(width_inches * dpi)
    height_px = int(height_inches * dpi)

    return width_px, height_px

# Example: 180mm wide figure at 300 DPI
width, height = calculate_dimensions(180, 120, dpi=300)
print(f"Required resolution: {width}x{height} pixels")
# Output: Required resolution: 2126x1417 pixels

# R ggplot2 export with proper DPI
library(ggplot2)

# Create plot
p <- ggplot(mtcars, aes(x = wt, y = mpg)) +
  geom_point() +
  theme_minimal(base_size = 12)

# Save for publication (300 DPI)
ggsave(
  filename = "figure1.png",
  plot = p,
  width = 180,
  height = 120,
  units = "mm",
  dpi = 300
)

# Save as vector for flexibility
ggsave(
  filename = "figure1.pdf",
  plot = p,
  width = 180,
  height = 120,
  units = "mm",
  device = cairo_pdf  # Better text rendering
)

期待結果: Graphics rendered at correct resolution for print quality 失敗時: Verify DPI metadata saved correctly, check file size appropriate

3. Configure Color Space

Set appropriate color profile:

from PIL import Image, ImageCms

def convert_to_cmyk(rgb_image_path, cmyk_output_path):
    """Convert RGB to CMYK for print."""
    img = Image.open(rgb_image_path)

    if img.mode != 'RGB':
        img = img.convert('RGB')

    # Convert to CMYK
    cmyk_img = img.convert('CMYK')
    cmyk_img.save(cmyk_output_path, format='TIFF', compression='tiff_lzw')
    print(f"Converted to CMYK: {cmyk_output_path}")

def apply_srgb_profile(image_path, output_path):
    """Apply sRGB profile for web."""
    img = Image.open(image_path)

    # sRGB profile (embedded in Pillow)
    srgb_profile = ImageCms.createProfile('sRGB')

    # Convert to sRGB
    img_srgb = ImageCms.profileToProfile(
        img,
        srgb_profile,
        srgb_profile,
        renderingIntent=ImageCms.Intent.PERCEPTUAL
    )

    img_srgb.save(output_path)

# ImageMagick for color space conversion
convert input.png -colorspace sRGB output_srgb.png
convert input.png -colorspace CMYK output_cmyk.tiff

# Check color profile
identify -verbose image.png | grep -i colorspace

期待結果: Color space matches publication requirements 失敗時: Verify color profile embedded, test print preview

4. Configure Typography

Ensure text is readable and properly formatted:

from PIL import ImageFont

def get_publication_fonts():
    """Load fonts appropriate for publication."""
    # Common publication-safe fonts
    fonts = {
        'serif': 'Times New Roman',
        'sans': 'Arial',
        'mono': 'Courier New'
    }

    try:
        # Load with proper size for DPI
        # At 300 DPI, 12pt = 12 * 300/72 = 50 pixels
        base_size_300dpi = 50

        font_regular = ImageFont.truetype(f"{fonts['sans']}.ttf", base_size_300dpi)
        font_bold = ImageFont.truetype(f"{fonts['sans']} Bold.ttf", base_size_300dpi)

        return {'regular': font_regular, 'bold': font_bold}
    except:
        return {'regular': ImageFont.load_default(), 'bold': ImageFont.load_default()}

# Typography guidelines
typography_specs = {
    'minimum_font_size': '8pt',  # Readable when printed
    'line_width_min': 0.5,  # Points, for print clarity
    'panel_labels': {
        'font': 'Arial Bold',
        'size': '12pt',
        'position': 'top-left',
        'style': 'A, B, C'  # Or (a), (b), (c)
    },
    'axis_labels': {
        'font': 'Arial',
        'size': '10pt'
    },
    'legend': {
        'font': 'Arial',
        'size': '9pt',
        'position': 'outside plot area'
    }
}

# R publication-quality typography
library(ggplot2)

p <- ggplot(mtcars, aes(x = wt, y = mpg)) +
  geom_point(size = 2) +
  labs(
    title = "Fuel Efficiency vs Weight",
    x = "Weight (1000 lbs)",
    y = "Miles per Gallon"
  ) +
  theme_bw(base_size = 12, base_family = "Arial") +
  theme(
    plot.title = element_text(size = 14, face = "bold"),
    axis.title = element_text(size = 12),
    axis.text = element_text(size = 10),
    legend.text = element_text(size = 10),
    panel.grid.minor = element_blank(),
    # Ensure text is black for print
    text = element_text(color = "black")
  )

期待結果: Text readable at publication size, fonts embedded properly 失敗時: Increase font sizes, check font licensing, convert text to outlines

5. Select Appropriate File Format

Choose format based on use case:

def export_multi_format(source_path, output_base, formats=['png', 'pdf', 'tiff']):
    """Export graphic in multiple formats."""
    from PIL import Image
    import cairosvg
    import os

    base, ext = os.path.splitext(output_base)

    if ext.lower() in ['.svg']:
        # SVG source - convert to rasters
        for fmt in formats:
            output = f"{base}.{fmt}"

            if fmt == 'png':
                cairosvg.svg2png(
                    url=source_path,
                    write_to=output,
                    output_width=2126,  # 180mm @ 300 DPI
                    output_height=1417   # 120mm @ 300 DPI
                )
            elif fmt == 'pdf':
                cairosvg.svg2pdf(url=source_path, write_to=output)
            elif fmt == 'tiff':
                # Convert via PNG intermediate
                temp_png = f"{base}_temp.png"
                cairosvg.svg2png(url=source_path, write_to=temp_png)
                img = Image.open(temp_png)
                img.save(output, format='TIFF', compression='tiff_lzw')
                os.remove(temp_png)

    else:
        # Raster source
        img = Image.open(source_path)

        for fmt in formats:
            output = f"{base}.{fmt}"

            if fmt == 'png':
                img.save(output, format='PNG', dpi=(300, 300), optimize=True)
            elif fmt == 'tiff':
                img.save(output, format='TIFF', compression='tiff_lzw', dpi=(300, 300))
            elif fmt == 'pdf':
                # Use img2pdf or similar for raster-to-PDF
                img.save(output, format='PDF', resolution=300.0)

    print(f"Exported in formats: {', '.join(formats)}")

# Format selection guide
format_guide = {
    'TIFF': {
        'use_for': 'Journal submission, archival',
        'benefits': 'Lossless, supports CMYK, high quality',
        'compression': 'LZW or ZIP (lossless)'
    },
    'PDF': {
        'use_for': 'Submission, print, archival',
        'benefits': 'Vector or raster, text searchable, widely accepted',
        'variants': 'PDF/A (archival), PDF/X (print)'
    },
    'PNG': {
        'use_for': 'Web, presentations, digital',
        'benefits': 'Lossless, transparency, good compression',
        'limitation': 'RGB only, larger than JPEG'
    },
    'SVG': {
        'use_for': 'Web, further editing, scalable graphics',
        'benefits': 'Vector, infinitely scalable, small file size',
        'limitation': 'Not always accepted by journals'
    },
    'EPS': {
        'use_for': 'Legacy journal requirements',
        'benefits': 'Vector format accepted by older systems',
        'limitation': 'Being phased out, use PDF instead'
    }
}

期待結果: Appropriate format for publication channel 失敗時: Check publisher requirements, provide multiple formats

6. Optimize for Web

Create web-optimized versions:

def optimize_for_web(input_path, output_path, max_width=1200, quality=85):
    """Optimize image for web publication."""
    from PIL import Image

    img = Image.open(input_path)

    # Resize if too large
    if img.width > max_width:
        ratio = max_width / img.width
        new_height = int(img.height * ratio)
        img = img.resize((max_width, new_height), Image.LANCZOS)

    # Convert to RGB if needed
    if img.mode in ('RGBA', 'LA', 'P'):
        background = Image.new('RGB', img.size, (255, 255, 255))
        if img.mode == 'P':
            img = img.convert('RGBA')
        background.paste(img, mask=img.split()[-1] if 'A' in img.mode else None)
        img = background

    # Save optimized
    img.save(output_path, format='JPEG', quality=quality, optimize=True, progressive=True)

    # Check file size
    import os
    file_size_kb = os.path.getsize(output_path) / 1024
    print(f"Optimized: {file_size_kb:.1f} KB")

def create_responsive_set(input_path, output_base):
    """Create multiple resolutions for responsive web."""
    from PIL import Image

    img = Image.open(input_path)
    sizes = [
        (640, '640w'),
        (1024, '1024w'),
        (1920, '1920w')
    ]

    for width, suffix in sizes:
        if img.width >= width:
            ratio = width / img.width
            height = int(img.height * ratio)
            resized = img.resize((width, height), Image.LANCZOS)

            output = f"{output_base}_{suffix}.jpg"
            resized.save(output, format='JPEG', quality=85, optimize=True)

期待結果: Web-optimized images under 500KB, responsive sizes generated 失敗時: Reduce quality, resize further, consider WebP format

7. Embed Metadata

Add descriptive metadata for archival:

from PIL import Image
from PIL.PngImagePlugin import PngInfo

def embed_metadata(image_path, output_path, metadata):
    """Embed metadata in PNG."""
    img = Image.open(image_path)

    # Create metadata
    png_info = PngInfo()
    for key, value in metadata.items():
        png_info.add_text(key, str(value))

    # Save with metadata
    img.save(output_path, format='PNG', pnginfo=png_info)

# Example metadata
metadata = {
    'Title': 'Figure 1: Relationship between weight and fuel efficiency',
    'Author': 'Jane Doe',
    'Description': 'Scatter plot showing negative correlation',
    'Copyright': 'CC-BY 4.0',
    'Software': 'R 4.3.0, ggplot2 3.4.0',
    'Creation Date': '2026-02-16',
    'Source': 'mtcars dataset'
}

embed_metadata('figure1.png', 'figure1_with_metadata.png', metadata)

期待結果: Metadata embedded and retrievable 失敗時: Check format supports metadata (PNG, TIFF, PDF yes; JPEG limited)

バリデーション Checklist

• DPI meets publication requirements (typically 300+)
• Physical dimensions correct for publication
• Color space appropriate (RGB for web, CMYK for print)
• File format accepted by publisher
• Text is readable at publication size
• Fonts embedded or outlined
• Line widths visible when printed
• Color contrast sufficient for grayscale printing
• File size within limits
• Metadata embedded
• Tested print preview or rendering

よくある落とし穴

1. Insufficient resolution: 72 DPI web graphics cannot be printed at quality
2. Wrong color space: RGB graphics may print differently than displayed
3. Font substitution: Non-embedded fonts replaced with defaults
4. Small text: Fonts below 8pt may be illegible when printed
5. Thin lines: Lines below 0.5pt may not print clearly
6. File size: High DPI graphics can be very large, compress appropriately
7. Compression artifacts: JPEG compression unsuitable for line art or text
8. Missing bleed: Print graphics need 3-5mm bleed beyond trim
9. Transparency issues: Some formats don't preserve transparency correctly
10. Aspect ratio: Distortion from incorrect dimension calculations

関連スキル

• create-2d-composition: Creating the source graphics
• render-blender-output: 3D rendering settings for publication
• generate-quarto-report: Integrating graphics into documents