ROS Package bob_flux2

The bob_flux2 package provides a ROS 2 node for generating images using the FLUX.2 model. It supports both pure text-to-image (TTI) and image-to-image (ITTI) generation, optimized for memory efficiency by sequentially loading model components.

Features

• Memory Efficient: Loads and unloads the text encoder and transformer sequentially to stay within VRAM limits.
• High Quality: Quantized 4-bit support for high-quality generation on consumer GPUs.
• Flexible Filenaming: Automatic filename generation with counters and random suffixes.
• Image Publishing: Publishes generated images directly to the generated_image topic using cv_bridge.
• GPU Optimized: Specifically optimized for consumer GPUs with 24GB VRAM (e.g., NVIDIA RTX 4090), ensuring smooth execution within these hardware limits.

Setup and Installation

1. Clone the Repository

Navigate to your ROS 2 workspace src directory and clone the package:

cd ~/ros2_ws/src
git clone https://github.com/bob-ros2/bob_flux2.git

2. Install Dependencies

It is highly recommended to use a Python virtual environment (venv) to avoid library version conflicts and maintain a clean system environment.

Once your environment is active, install the required packages:

pip install -r requirements.txt

Note

Ensure cv_bridge and sensor_msgs are present in your ROS 2 environment. These are usually included in the desktop installation or can be installed via apt install ros-<distro>-cv-bridge.

3. Build the Package

From the root of your ROS 2 workspace:

colcon build --packages-select bob_flux2
source install/setup.bash

Parameters

Parameter	Type	Default	Env Variable	Description
repo_id	string	diffusers/FLUX.2-dev-bnb-4bit	FLUX2_REPO_ID	The Hugging Face repository ID.
model_dir	string	./models	FLUX2_MODEL_DIR	Directory to cache models.
device	string	cuda:0	FLUX2_DEVICE	Torch device to use (e.g., cuda:0 or cpu).
prompt	string	''	FLUX2_PROMPT	Initial prompt to run at startup.
input_image	string	''	FLUX2_INPUT_IMAGE	Path or URL to an input image for ITTI.
once	bool	false	FLUX2_ONCE	If true, the node exits after one generation.
image_path	string	''	FLUX2_IMAGE_PATH	Save path. Ends with auto for autogeneration.
seed	int	-1	FLUX2_SEED	Seed for generation (-1 for random).
image_counter_start	int	1	FLUX2_IMAGE_COUNTER_START	Starting value for the filename counter.

Topics

Subscribed Topics

• prompt (std_msgs/String): Receives text prompts for image generation.

Published Topics

• generated_image (sensor_msgs/Image): Publishes the generated image.

Usage

Using the Example Configuration

The package includes a sample configuration file at config/tti.yaml. This is the easiest way to start the node with customized settings.

ros2 run bob_flux2 flux2_node --ros-args --params-file src/bob_flux2/config/tti.yaml

Command Line Examples

Simple Text-to-Image

ros2 run bob_flux2 flux2_node --ros-args -p prompt:="A futuristic city in the style of cyberpunk"

Save with Auto-filenaming

Setting image_path to a path ending in auto will generate files like auto_0001_rtRfTDrt.png.

ros2 run bob_flux2 flux2_node --ros-args \
    -p image_path:=/path/to/output/auto \
    -p image_counter_start:=1

Image-to-Image (ITTI)

ros2 run bob_flux2 flux2_node --ros-args \
    -p input_image:=/path/to/input.png \
    -p prompt:="Make it look like a oil painting"