app.py

import os
import gradio as gr

from haystack.components.generators.chat import HuggingFaceAPIChatGenerator
from haystack.components.builders.chat_prompt_builder import ChatPromptBuilder
from haystack.dataclasses import ChatMessage
from haystack import Pipeline
from haystack.utils import Secret
from image_captioner import ImageCaptioner

description = """
# Captionate 📸
### Create Instagram captions for your pics!

* Upload your photo or select one from the examples
* Choose your model
* ✨ Captionate! ✨ 

It uses [Salesforce/blip-image-captioning-base](https://huggingface.co/Salesforce/blip-image-captioning-base) model for image-to-text caption generation task.

For Instagrammable captions, try different text-to-text models to see how they react to the same prompt.

Built by [Bilge Yucel](https://twitter.com/bilgeycl) using [Haystack](https://github.com/deepset-ai/haystack) 💙
"""

prompt_template =[ChatMessage.from_user("""
You will receive a descriptive text of a photo.
Try to generate a nice Instagram caption with a phrase rhyming with the text. Include emojis in the caption.
Just return one option without alternatives. Don't use hashtags.           
                                                                                 
Descriptive text: {{caption}};
Instagram Caption:
""")]

hf_api_key = os.environ["HF_API_KEY"]

def generate_caption(image_file_path, model_name):
    image_to_text = ImageCaptioner(model_name="Salesforce/blip-image-captioning-base")
    prompt_builder = ChatPromptBuilder(template=prompt_template, required_variables="*")
    generator = HuggingFaceAPIChatGenerator(
        api_type="serverless_inference_api", 
        api_params={"model": model_name}, 
        token=Secret.from_token(hf_api_key))
    
    captioning_pipeline = Pipeline()
    captioning_pipeline.add_component("image_to_text", image_to_text)
    captioning_pipeline.add_component("prompt_builder", prompt_builder)
    captioning_pipeline.add_component("generator", generator)
    
    captioning_pipeline.connect("image_to_text.caption", "prompt_builder.caption")
    captioning_pipeline.connect("prompt_builder", "generator")

    result = captioning_pipeline.run({"image_to_text":{"image_file_path":image_file_path}})
    return result["generator"]["replies"][0].text

with gr.Blocks(theme="soft") as demo:
    gr.Markdown(value=description)
    with gr.Row():
        image = gr.Image(type="filepath")
        with gr.Column():
            model_name = gr.Dropdown(
                ["deepseek-ai/DeepSeek-V3.1-Terminus", "meta-llama/Llama-3.3-70B-Instruct", "openai/gpt-oss-20b", "Qwen/Qwen3-4B-Instruct-2507"], 
                value="deepseek-ai/DeepSeek-V3.1-Terminus", 
                label="Choose your model!"
                )
            gr.Examples(["./whale.png", "./rainbow.jpeg", "./selfie.png"], inputs=image, label="Click on any example") 
    submit_btn = gr.Button("✨ Captionate ✨")
    caption = gr.Textbox(label="Caption", show_copy_button=True)
    submit_btn.click(fn=generate_caption, inputs=[image, model_name], outputs=[caption])

if __name__ == "__main__":
    demo.launch()