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Comparing ChatGPT Image and Nano Banana Pro Across 5 Use Cases

This guide shows you how to compare Google’s Nano Banana Pro with ChatGPT’s image generation model across a consistent set of use cases.

beginner 5 steps 1 resource

Introduction

This guide shows you how to compare Google’s Nano Banana Pro with ChatGPT’s image generation model across a consistent set of use cases. You’ll build a reusable comparison matrix, run the same prompts through each model, and score the results across consistency, creativity, utility, and quality. The example test uses five use cases and generates 4 images per model.

The source comparison also includes Google’s advanced image generation tool in AI Studio as an optional test.

If you don’t have Gemini Pro, you can use Nano Banana Pro for free. Try opening an incognito browser if you have trouble.

Step-by-step 5 steps

Instructions

  1. Step 1 of 5

    Choose use cases and testing rules

    Decide which image-generation use cases you want to compare. The example comparison uses five:

    • Logo for a taco truck
    • Website graphic for a couch manufacturer
    • Social post for an energy drink brand
    • Marketing materials for a travel agency
    • An arbitrary prompt for something that is easy to identify as fake

    Outline your testing rules before you generate anything. The example rules are:

    • Use the same prompt for each model.
    • Generate 4 images per model.
    • Grade each model from 1–5.
    • Score prompt consistency: how well it followed the prompt across variations.
    • Score creativity: whether the variations are noticeably different, subtly different, or near copies.
    • Score utility: whether one or more variations could be used for the actual use case.
    • Score quality: which images look the least like AI-generated “slop.”
  3. Step 2 of 5

    Generate structured prompts

    Feed your use cases into Claude, ChatGPT, or Gemini and ask it to generate structured JSON prompts for each one.

    Prompt 
    Here’s my use cases: [use cases]

Write me a JSON prompt for each of the 5 use cases. Invent a different, fun brand for each use case. For the arbitrary image, do something detailed and easy to see if it's fake, like a crowd of sports fans at an NBA game. Include instructions to generate 4 variations per prompt in a 4x4 grid.

    If you want to test this on your own brand, ask the LLM to interview you about your brand and then write prompts for each use case.

    To save time and tokens, ask the LLM to write a prompt that generates 4 variations in a 4x4 grid.
  4. Step 3 of 5

    Create your scoring matrix

    Create a scoring matrix for your comparison.

    Use this structure: | Use Case | Model | Consistency | Creativity | Utility | Quality | Overall Rating | |---|---|---|---|---|---|---| | Use case 1 | Nano Banana (Gemini) | | | | | | | Use case 2 | ChatGPT Image | | | | | | | Use case 3 | Nano Banana Pro (Vertex) | | | | | |

  5. Step 4 of 5

    Open the image tools

    • Navigate to Gemini.
    • Click the “Create image” button to add Nano Banana.
    2_nano_banana_input
    • Navigate to ChatGPT Images.
    • Optional: Open Nano Banana Pro in AI Studio. Click the “Playground” link on the left side to open new chats.
  6. Step 5 of 5

    Generate and score the outputs

    Feed each use-case prompt into each tool and generate the images.

    Open a new chat for each use case so you clear the context between tests.

    Rate each output against the criteria in your scoring matrix.

You're done

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Overview Back to the steps

Background and context

Who This Is Useful For

  • Business owners who want to automate asset creation
  • Graphic designers using AI for designs
  • Anyone who wants to generate better AI photos

What You Will Build

You’ll create a reusable model-comparison workflow and scoring matrix that can be used for future image model tests.

  • A set of image-generation use cases
  • Structured prompts for each use case
  • A scoring matrix for consistency, creativity, utility, quality, and overall rating
  • A repeatable process for comparing ChatGPT Image, Nano Banana Pro, and optionally AI Studio
1_whatyouwillbuild

What You Need

  • Gemini Pro account
  • Free or paid ChatGPT account
  • Optional: Google Workspace account with billing enabled for AI Studio
  • Optional: Notion template for your rating matrix

Going Further

  • Try a few of the use cases with your own brand in both ChatGPT Image and Nano Banana Pro.
  • Use ChatGPT or Gemini to interview you about your brand and turn the answers into 1–3 image prompt variations.
  • Ask for variations in a 4x4 grid, then generate the best result by itself once you find one you like.