Generate Print-Ready Book Covers Programmatically

The Cover Problem for Self-Publishers

You've written the book. Now you need a cover. Every format needs its own — Kindle ebook, KDP paperback, hardcover, audiobook thumbnail. Each with different dimensions, different bleed requirements, different text placement. A professional designer charges $500-1,500 per cover. Canva gives you templates that look like every other self-published book on Amazon.

If you're publishing one book, you hire the designer. If you're publishing ten books a year — or running a publishing platform that handles hundreds of authors — manual design doesn't scale.

The Iteration Layer's Image Generation API generates print-ready book covers from a JSON template. Define your cover layout — background, title, author name, decorative elements, optional cover image — and generate it in one API call. Change the title, get a new cover. Change the format, get the right dimensions. No design tool, no export step, no manual work per variant.

Print Dimensions: Getting the Math Right

Print-on-demand platforms have strict dimension requirements. Amazon KDP specifies dimensions in inches at 300 DPI. The API works in pixels. The conversion is straightforward.

For a standard 6"x9" paperback front cover at 300 DPI:

Width: 6 x 300 = 1800 pixels
Height: 9 x 300 = 2700 pixels

Common book cover dimensions:

Format	Inches	Pixels at 300 DPI
KDP Paperback (6"x9")	6 x 9	1800 x 2700
KDP Paperback (5.5"x8.5")	5.5 x 8.5	1650 x 2550
Kindle Ebook	—	1600 x 2560
Audiobook Thumbnail	—	3200 x 3200
Square Social Promo	—	1080 x 1080

The same cover template can generate all of these by adjusting the composition dimensions and repositioning the layers.

A Fiction Cover Template

Here's a complete book cover for a fiction title — dark background, large serif title, author name, decorative line elements:

import { IterationLayer } from "iterationlayer";

const client = new IterationLayer({
  apiKey: "YOUR_API_KEY",
});

const result = await client.generateImage({
  dimensions: {
    width_in_px: 1800,
    height_in_px: 2700,
  },
  output_format: "png",
  fonts: [
    {
      name: "Playfair Display",
      weight: "Bold",
      style: "normal",
      file: {
        type: "url",
        name: "PlayfairDisplay-Bold.ttf",
        url: "https://cdn.example.com/fonts/PlayfairDisplay-Bold.ttf",
      },
    },
    {
      name: "Playfair Display",
      weight: "Regular",
      style: "italic",
      file: {
        type: "url",
        name: "PlayfairDisplay-Italic.ttf",
        url: "https://cdn.example.com/fonts/PlayfairDisplay-Italic.ttf",
      },
    },
    {
      name: "Lato",
      weight: "Light",
      style: "normal",
      file: {
        type: "url",
        name: "Lato-Light.ttf",
        url: "https://cdn.example.com/fonts/Lato-Light.ttf",
      },
    },
  ],
  layers: [
    {
      index: 0,
      type: "solid-color",
      hex_color: "#1C1917",
    },
    {
      index: 1,
      type: "solid-color",
      hex_color: "#A8A29E",
      position: {
        x_in_px: 200,
        y_in_px: 600,
      },
      dimensions: {
        width_in_px: 1400,
        height_in_px: 2,
      },
    },
    {
      index: 2,
      type: "solid-color",
      hex_color: "#A8A29E",
      position: {
        x_in_px: 200,
        y_in_px: 1900,
      },
      dimensions: {
        width_in_px: 1400,
        height_in_px: 2,
      },
    },
    {
      index: 3,
      type: "text",
      text: "THE LONG\nSILENCE",
      font_name: "Playfair Display",
      font_weight: "bold",
      font_size_in_px: 160,
      text_color: "#FAFAF9",
      text_align: "center",
      position: {
        x_in_px: 100,
        y_in_px: 700,
      },
      dimensions: {
        width_in_px: 1600,
        height_in_px: 600,
      },
    },
    {
      index: 4,
      type: "text",
      text: "A Novel",
      font_name: "Playfair Display",
      font_size_in_px: 48,
      text_color: "#A8A29E",
      text_align: "center",
      position: {
        x_in_px: 100,
        y_in_px: 1350,
      },
      dimensions: {
        width_in_px: 1600,
        height_in_px: 100,
      },
    },
    {
      index: 5,
      type: "text",
      text: "ELIZABETH ASHWORTH",
      font_name: "Lato",
      font_size_in_px: 52,
      text_color: "#D6D3D1",
      text_align: "center",
      position: {
        x_in_px: 100,
        y_in_px: 2000,
      },
      dimensions: {
        width_in_px: 1600,
        height_in_px: 100,
      },
    },
  ],
});

{
  "success": true,
  "data": {
    "buffer": "iVBORw0KGgoAAAANSUhEUg...",
    "mime_type": "image/png"
  }
}

The template uses three fonts: Playfair Display Bold for the title, Playfair Display Italic for the subtitle, and Lato Light for the author name. This is a classic fiction cover typography stack — a serif display font for impact, a light sans-serif for the byline.

The decorative rectangles at 2px height serve as horizontal rules, framing the title area. Simple, but they add structure to the composition.

Adding a Cover Image

Not every cover is typography-only. Many genres — thriller, romance, sci-fi — expect a photographic or illustrated cover. Add a background image using the static-image layer or image-overlay:

// Replace the solid-color with an image
{
  index: 0,
  type: "image",
  file: {
    type: "url",
    name: "mountain-landscape.jpg",
    url: "https://cdn.example.com/covers/mountain-landscape.jpg",
  },
  position: {
    x_in_px: 0,
    y_in_px: 0,
  },
  dimensions: {
    width_in_px: 1800,
    height_in_px: 2700,
  },
  should_use_smart_cropping: true,
},
// Add a dark overlay so text remains readable
{
  index: 1,
  type: "image",
  file: {
    type: "url",
    name: "dark-gradient.png",
    url: "https://cdn.example.com/overlays/dark-gradient.png",
  },
  opacity: 70,
  should_use_smart_cropping: false,
},

The static-image fills the full cover area. Smart cropping positions the focal point of the photo correctly — a mountain peak stays centered, a cityscape keeps the skyline visible. The image-overlay adds a dark gradient so white or light title text remains readable against any background photo.

Font Handling for Publishing

Typography makes or breaks a book cover. The API accepts TTF, OTF, WOFF, and WOFF2 font files via the fonts array. Each font entry specifies the family name, weight, and style — so you can use bold for titles and light for bylines from the same family.

Genre conventions matter here. Literary fiction tends toward serif display fonts — Playfair Display, Cormorant, EB Garamond. Thrillers go bold and condensed — Oswald, Bebas Neue, Impact. Romance leans into scripts and elegant serifs. Non-fiction often uses clean sans-serifs — Inter, Montserrat, Source Sans.

The key advantage of programmatic generation: once you've chosen your typography for a series, every book in the series gets the same fonts, the same spacing, the same weight. Consistency you'd otherwise enforce through a brand guide and hope your designer follows.

Series Consistency

When you're publishing a series, visual consistency across covers sells books. Same font, same layout, same color scheme — different title and maybe a different accent color per book.

const seriesBooks = [
  {
    title: "THE LONG\nSILENCE",
    accentColor: "#A8A29E",
    number: 1,
  },
  {
    title: "THE DEEP\nCURRENT",
    accentColor: "#7C9885",
    number: 2,
  },
  {
    title: "THE LAST\nWITNESS",
    accentColor: "#9B8B7A",
    number: 3,
  },
];

const covers = await Promise.all(
  seriesBooks.map(async (book) => {
    const result = await client.generateImage({
      dimensions: {
        width_in_px: 1800,
        height_in_px: 2700,
      },
      output_format: "png",
      fonts: [/* same font config for the series */],
      layers: [
        {
          index: 0,
          type: "solid-color",
          hex_color: "#1C1917",
        },
        {
          index: 1,
          type: "solid-color",
          position: {
            x_in_px: 200,
            y_in_px: 600,
          },
          dimensions: {
            width_in_px: 1400,
            height_in_px: 2,
          },
          hex_color: book.accentColor,
        },
        {
          index: 2,
          type: "solid-color",
          position: {
            x_in_px: 200,
            y_in_px: 1900,
          },
          dimensions: {
            width_in_px: 1400,
            height_in_px: 2,
          },
          hex_color: book.accentColor,
        },
        {
          index: 3,
          type: "text",
          text: `**${book.title}**`,
          position: {
            x_in_px: 100,
            y_in_px: 700,
          },
          dimensions: {
            width_in_px: 1600,
            height_in_px: 600,
          },
          font_name: "Playfair Display",
          font_weight: "bold",
          font_size_in_px: 160,
          text_color: "#FAFAF9",
          text_align: "center",
          vertical_align: "center",
          is_splitting_lines: true,
        },
        {
          index: 4,
          type: "text",
          text: "ELIZABETH ASHWORTH",
          position: {
            x_in_px: 100,
            y_in_px: 2000,
          },
          dimensions: {
            width_in_px: 1600,
            height_in_px: 100,
          },
          font_name: "Lato",
          font_weight: "light",
          font_size_in_px: 52,
          text_color: "#D6D3D1",
          text_align: "center",
          vertical_align: "center",
        },
      ],
    });

    return {
      title: book.title,
      number: book.number,
      buffer: Buffer.from(result.data.buffer, "base64"),
    };
  })
);

Three covers, same template, same typography, different titles and accent colors. The series looks cohesive on a bookshelf — digital or physical.

Multi-Format Generation

A single book needs multiple cover formats. The Kindle version needs 1600x2560. The paperback needs 1800x2700. The audiobook square needs 3200x3200. A social media promo card needs 1080x1080.

Same template logic, different dimension parameters. You can build a function that takes a book's metadata and a format spec, then generates the appropriate cover:

const formatSpecs = [
  {
    name: "kindle",
    width_in_px: 1600,
    height_in_px: 2560,
    titleSize: 140,
  },
  {
    name: "paperback",
    width_in_px: 1800,
    height_in_px: 2700,
    titleSize: 160,
  },
  {
    name: "audiobook",
    width_in_px: 3200,
    height_in_px: 3200,
    titleSize: 220,
  },
  {
    name: "social",
    width_in_px: 1080,
    height_in_px: 1080,
    titleSize: 80,
  },
];

For each format, adjust the font size and layer positions proportionally to the canvas dimensions. The audiobook square needs a larger title to fill the space. The social card needs everything compressed into a smaller area.

Why Not Canva or AI Image Generators

Canva templates work for one-off covers. But they don't integrate into a publishing pipeline. You can't call Canva from your book management system, pass in the title and author, and get back a cover image. Every cover requires manual clicks.

AI image generators (Midjourney, DALL-E) produce impressive visuals, but they don't produce print-ready covers. You can't control typography precisely — the title might be misspelled, the font won't match your series, and the dimensions won't be exact. You'd still need to composite the AI art with your text in a design tool.

The API gives you pixel-level control over layout and typography while accepting any image — stock photos, AI-generated art, illustrations — as input layers. You get the creative flexibility of a design tool with the automation of an API.

Get Started

Check the docs for the full layer reference, font configuration, and output format options. The TypeScript and Python SDKs handle authentication and response parsing.

Sign up for a free account — no credit card required. Generate your first cover and see how it compares to your current workflow.

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