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File Requirements

Panels Store supports multiple comic file formats to give you flexibility in how you publish your work.

Supported Formats​

Archive Formats​

The following formats are simply a compressed folder containing properly named images (i.e. 001.png, 002.png, 003.png, etc). You can also choose to add an additional metadata file (ie. ComicInfo.xml).

  • ZIP - Standard zip archive
  • RAR - RAR compressed archive
  • 7zip - 7-Zip comic book archive
  • CB7 - 7-Zip comic book archive
  • CBZ - Comic Book ZIP archive
  • CBR - Comic Book RAR archive

Document Formats​

  • PDF - Portable Document Format
  • EPUB - Electronic Publication (for digital-first comics)
Recommended Format

CBZ (Comic Book ZIP) is the most widely supported format and recommended for most publishers.

File Size Guidelines​

There is no hard limit on file size, but we recommend following these best practices:

Standard Comics (20-30 pages)

  • Target: 50-150 MB
  • Maximum recommended: 300 MB

Graphic Novels (100+ pages)

  • Target: 150-400 MB
  • Maximum recommended: 800 MB

Why File Size Matters:

  • Faster uploads for you
  • Faster downloads for readers
  • Better reading experience on mobile devices
  • Reduced processing time

Optimizing File Size​

Balance Quality and Size:

  • Use appropriate image compression
  • Don't exceed necessary resolution
  • Remove unnecessary metadata
  • Optimize before archiving
warning

While there's no strict limit, extremely large files (1GB+) may experience longer upload and processing times. Aim to keep files optimized.

Image Quality Guidelines​

Resolution​

Recommended Specs:

  • Width: 1280-2048 pixels
  • DPI: 150-300 for digital reading
  • Format: JPG or PNG

Why This Resolution:

  • Looks great on modern screens
  • Supports zooming without pixelation
  • Reasonable file sizes
  • Good balance for retina displays

Image Format Inside Archives​

JPG (Recommended)

  • Smaller file sizes
  • Good quality at 85-95% compression
  • Best for most comic pages

PNG

  • Larger file sizes
  • Lossless quality
  • Good for line art or text-heavy pages
  • Use when you need transparency

Color Space​

  • RGB for digital comics (recommended)
  • Avoid CMYK (print color space)
  • sRGB color profile is ideal

File Structure​

For Archive Files (CBZ, CBR, etc.)​

Your archive should contain images in proper reading order:

comic-name.cbz
├── page_001.jpg
├── page_002.jpg
├── page_003.jpg
└── ...

Important:

  • The first image will be used for the cover
  • Name files to maintain correct page order
  • Use leading zeros (001, 002, not 1, 2)
  • Don't include folders, images should be at root level of archive
  • Remove any system files (.DS_Store, thumbs.db)

For PDF Files​

  • Pages should be in correct reading order
  • Ensure PDF is not password protected
  • Avoid excessive DRM that may interfere with our reader

Testing Your Files​

Before Publishing​

If you want to test your file before publishing, we recommend using the Panels app (iOS, iPadOS or Mac). Just import your file to the app and open it.

  • Windows: CDisplayEx, YACReader
  • Linux: Komikku, MComix
  • Android: Perfect Viewer

Common Issues and Solutions​

Issue: Pages Out of Order​

Solution:

  • Rename files with leading zeros (001, 002, 003)
  • Ensure alphabetical sorting matches reading order
  • Recreate the archive with properly named files

Issue: File Too Large​

Solution:

  • Reduce image resolution if above 2048px wide
  • Increase JPG compression to 85-90%
  • Convert PNG files to JPG if they don't need transparency
  • Use compression tools like ImageOptim or JPEGmini

Issue: Poor Image Quality​

Solution:

  • Start with higher quality source images
  • Don't over-compress JPGs (keep quality at 85% minimum)
  • Ensure images are at least 1280px wide
  • Check that images aren't being double-compressed

Issue: Archive Won't Upload​

Solution:

  • Verify file format is supported
  • Check that file isn't corrupted (try opening it locally)
  • Ensure no special characters in filename
  • Try creating a fresh archive

Best Practices​

Creating Quality Comic Files​

  1. Start with high-quality source files

    • Export from your creative software at appropriate resolution
    • Don't start with low-res images

  2. Optimize before archiving

    • Compress images appropriately
    • Remove unnecessary metadata
    • Ensure consistent dimensions across pages

  3. Use consistent naming

    • Descriptive file names help with organization
    • Sequential numbering prevents ordering issues

  4. Test before publishing

    • Always test your file in a reader before uploading
    • Check on multiple devices if possible

Next Steps​

Once you have your file ready:

  1. Learn About Comic Metadata - titles, descriptions, pricing
  2. Organize Comics into Series