How to Build an OpenAI Image Generation Workflow

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How to Build an OpenAI Image Generation Workflow

These notes are based on the YouTube video by The Boring Marketer

Overview of the Workflow

The workflow for generating custom thumbnail images using the GPT-4o image generation API involves four main tools:

N8N: for building the workflow
OpenAI: for accessing the GPT-4o image generation API (also referred to as “gpt-image-1”) and generating thumbnail concepts
Apify: for scraping and transcribing YouTube videos
Google Drive: for storing the final image files

Step-by-Step Process

The process can be broken down into the following steps:

Provide an input: a link to the YouTube video for which thumbnails are to be generated
Use OpenAI to analyze the video transcript and create:
- Thumbnail concepts
- Styles
- Character descriptions
- Prompts for the character to be created in the thumbnail
Use JSON to create a dynamic prompt and style for each image, allowing for multiple variations with different angles, text, etc. Note that the exact JSON structure should match the requirements of the GPT-4o image generation API.
Convert the format from Base64 to Image
Push the generated images to Google Drive

Technical Aspects

The conversion from Base64 to Image requires some technical setup, including:

// Example JSON prompt
{
  "prompt": "Create a thumbnail for a YouTube video with a cartoon-style avatar",
  "style": "animated",
  "character": "Lego-style"
}

The exact setup and definitions will be provided in a separate document. Please ensure that the JSON prompt structure aligns with the specifications of the GPT-4o image generation API.

Prompting Strategy

To generate effective thumbnail prompts, consider the following strategy:

Identify the 5-10 most emotionally or visually compelling hooks in the video transcript
For each hook, generate multiple thumbnail prompts, each styled after a different top-performing YouTube creator’s aesthetic
Add inspiration by including various channels and summaries of what they’re doing
Make it your own and come up with great prompts for your videos

Example Use Cases

The workflow can be used to generate a variety of thumbnail styles, including:

Cartoon versions of oneself
Lego-style avatars
Hyper-realistic looks, which are currently experimental and under development. While the workflow aspires to support hyper-realistic styles, this feature is not yet fully implemented and may require further updates to the GPT-4o image generation API.

Summary

The workflow for generating custom thumbnail images using the GPT-4o image generation API offers full creative control and can save a significant amount of time. By following the step-by-step process and using the prompting strategy, users can create effective thumbnail prompts and generate high-quality images. This workflow is accurate as of August 2025 and aligns with the current capabilities of the GPT-4o image generation API.

# How to Build an OpenAI Image Generation Workflow