Image to Image

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Overview

• Image + Text-to-Image (Editing): Provide an image and use text prompts to add, remove, or modify elements, change the style, or adjust the color grading.
• Multi-Image to Image (Composition & Style Transfer): Use multiple input images to compose a new scene or transfer the style from one image to another.
• Iterative Refinement: Engage in a conversation to progressively refine your image over multiple turns, making small adjustments until it’s perfect.
• High-Fidelity Text Rendering: Accurately generate images that contain legible and well-placed text, ideal for logos, diagrams, and posters.

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Supported inputs & outputs :

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Authentication

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Request Body

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Image to Image

curl -X POST "https://gptproto.com/v1/chat/completions" \
  -H "Authorization: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "messages": [
    {
      "role": "user",
      "content": "Two people standing together",
      "experimental_attachments": [
        {
          "contentType": "image/png",
          "url": "https://mgszhhytxjyitifbalro.supabase.co/storage/v1/object/public/chat-attachments/uploads/guakmauqtr.png"
        },
        {
          "contentType": "image/jpeg",
          "url": "https://mgszhhytxjyitifbalro.supabase.co/storage/v1/object/public/chat-attachments/uploads/3ox9ikxbcxc.jpeg"
        }
      ],
  	  "model": "gemini-2.5-flash-image"
    }
  ]
}'

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Response

{
  "candidates": [
      {
          "content": {
              "role": "model",
              "parts": [
                  {
                      "inlineData": {
                          "mimeType": "image/png",
                          "data": "base64"
                      }
                  }
              ]
          },
          "finishReason": "STOP"
      }
  ],
  "usageMetadata": {
      "promptTokenCount": 1302,
      "candidatesTokenCount": 1290,
      "totalTokenCount": 2592,
      "thoughtsTokenCount": 0,
      "promptTokensDetails": [
          {
              "modality": "IMAGE",
              "tokenCount": 1290
          },
          {
              "modality": "TEXT",
              "tokenCount": 12
          }
      ]
  },
  "modelVersion": "gemini-2.5-flash-image"
}

{
  "error": {
    "message": "Invalid signature",
    "type": "401"
  }
}

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Request Example

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Adding and removing elements

curl --location 'https://gptproto.com/v1/chat/completions' \
--header 'Authorization: sk-xxxx' \
--header 'Content-Type: application/json' \
--data '{
  "messages": [
    {
      "role": "user",
      "content": "Using the provided image of my cat, please add a small, knitted wizard hat on its head. Make it look like it's sitting comfortably and not falling off.",
      "experimental_attachments": [
        {
          "contentType": "image/png",
          "url": "image_url"
        }
      ],
  	  "model": "gemini-2.5-flash-image-preview"
    }
  ]
}'

Input	Output
A photorealistic picture of a fluffy ginger cat…	Using the provided image of my cat, please add a small, knitted wizard hat…

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Advanced composition: Combining multiple images

curl --location 'https://gptproto.com/v1/chat/completions' \
--header 'Authorization: sk-xxxx' \
--header 'Content-Type: application/json' \
--data '{
  "messages": [
    {
      "role": "user",
      "content": "Create a professional e-commerce fashion photo. Take the blue floral dress from the first image and let the woman from the second image wear it. Generate a realistic, full-body shot of the woman wearing the dress, with the lighting and shadows adjusted to match the outdoor environment.",
      "experimental_attachments": [
        {
          "contentType": "image/png",
          "url": "image_url_1"
        },{
          "contentType": "image/png",
          "url": "image_url_2"
        }
      ],
  	  "model": "gemini-2.5-flash-image-preview"
    }
  ]
}'

Input1	Input2	Output
A professionally shot photo of a blue floral summer dress…	Full-body shot of a woman with her hair in a bun…	Create a professional e-commerce fashion photo…

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Best Practices

• Be Hyper-Specific: The more detail you provide, the more control you have. Instead of “fantasy armor,” describe it: “ornate elven plate armor, etched with silver leaf patterns, with a high collar and pauldrons shaped like falcon wings.”
• Provide Context and Intent: Explain the purpose of the image. The model’s understanding of context will influence the final output. For example, “Create a logo for a high-end, minimalist skincare brand” will yield better results than just “Create a logo.”
• Iterate and Refine: Don’t expect a perfect image on the first try. Use the conversational nature of the model to make small changes. Follow up with prompts like, “That’s great, but can you make the lighting a bit warmer?” or “Keep everything the same, but change the character’s expression to be more serious.”
• Use Step-by-Step Instructions: For complex scenes with many elements, break your prompt into steps. “First, create a background of a serene, misty forest at dawn. Then, in the foreground, add a moss-covered ancient stone altar. Finally, place a single, glowing sword on top of the altar.”
• Use “Semantic Negative Prompts”: Instead of saying “no cars,” describe the desired scene positively: “an empty, deserted street with no signs of traffic.”
• Control the Camera: Use photographic and cinematic language to control the composition. Terms like wide-angle shot, macro shot, low-angle perspective.

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Limitations

• For best performance, use the following languages: EN, es-MX, ja-JP, zh-CN, hi-IN.
• Image generation does not support audio or video inputs.
• The model won’t always follow the exact number of image outputs that the user explicitly asks for.
• The model works best with up to 3 images as an input.
• When generating text for an image, Gemini works best if you first generate the text and then ask for an image with the text.
• Uploading images of children is not currently supported in EEA, CH, and UK.