Image Editing

FLUX.1 Kontext [pro] is a model designed for Text-to-Image generation and advanced Image Editing. This guide focuses on its Image Editing capabilities. Unlike other models, you don’t need to fine-tune or create complex workflows to achieve this - FLUX.1 Kontext [pro] handles it out of the box.

FLUX.1 Kontext’s image editing, accessed via the /flux-kontext-pro endpoint, provides the following key functionalities:

• Simple Editing: Change specific parts of an image while keeping the rest untouched
• Smart Changes: Make edits that look natural and fit with the rest of the image
• Text in Images: Add or modify text within your images

For comprehensive prompting techniques and advanced editing strategies, see our detailed Prompting Guide - Image-to-Image.

Examples of Editing

Basic Object Modifications

FLUX.1 Kontext is really good at straightforward object modification, for example if we want to change the colour of an object, we can prompt it.

For example: Change the car color to red

Before editing

After editing

Iterative Editing

FLUX.1 Kontext excels at character consistency, even after multiple edits. Starting from a reference picture, we can see that the character is consistent throughout the sequence. The prompts used for each edit are shown in the captions below each image.

Input Image

Remove the object from her face

She is now taking a selfie in the streets of Freiburg, it’s a lovely day out.

It’s now snowing, everything is covered in snow.

Text Editing

FLUX.1 Kontext can directly edit text that appears in images, making it easy to update signs, posters, labels, and more without recreating the entire image.

The most effective way to edit text is using quotation marks around the specific text you want to change:

Prompt Structure: Replace '[original text]' with '[new text]'

Example - We can see below where we have an input image with “Choose joy” written, and we replace “joy” with “BFL” - note the upper case format for BFL.

Input image

JOY replaced with BFL

Input image

Sync & Bloom changed to 'FLUX & JOY'

Using FLUX.1 Kontext API for Image Editing

This requires both a text prompt and an input image to work, with the input image serving as the base that will be edited according to your prompt.

To use Kontext for image editing, you’ll make a request to the /flux-kontext-pro endpoint:

Create Request

create_request.sh

# Install `curl` and `jq`, then run:
request=$(curl -X POST \
  'https://api.bfl.ai/v1/flux-kontext-pro' \
  -H 'accept: application/json' \
  -H "x-key: ${BFL_API_KEY}" \
  -H 'Content-Type: application/json' \
  -d '{
    "prompt": "<What you want to edit on the image>",
    "input_image": "<base64 converted image>",
}')
echo $request
request_id=$(echo $request | jq -r .id)
polling_url=$(echo $request | jq -r .polling_url)

A successful response will be a json object containing the request’s id, that will be used to retrieve the actual result.

Poll for Result

After submitting a request, you need to poll using the returned polling_url to retrieve the output when ready.

poll_result.sh

while true; do
  sleep 0.5
  result=$(curl -s -X 'GET' \
    "${polling_url}" \
    -H 'accept: application/json' \
    -H "x-key: ${BFL_API_KEY}")
  
  status=$(echo $result | jq -r .status)
  echo "Status: $status"
  
  if [ "$status" == "Ready" ]; then
    echo "Result: $(echo $result | jq -r .result.sample)"
    break
  elif [ "$status" == "Error" ] || [ "$status" == "Failed" ]; then
    echo "Generation failed: $result"
    break
  fi
done

A successful response will be a json object containing the result, and result['sample'] is a signed URL for retrieval.

Our signed URLs are only valid for 10 minutes. Please retrieve your result within this timeframe.

FLUX.1 Kontext Image Editing Parameters

For image editing, FLUX.1 Kontext tries to match the input image dimensions as closely as possible (rounded to multiples of 32). Use aspect_ratio to override this behavior if needed.

• Supported Range: Aspect ratios can range from 3:7 (portrait) to 7:3 (landscape).

List of FLUX.1 Kontext parameters for image editing via the /flux-kontext-pro endpoint:

Parameter	Type	Default	Description	Required
prompt	string		Text description of the edit to be applied.	Yes
input_image	string		Base64 encoded image to use as reference. Supports up to 20MB or 20 megapixels.	Yes
aspect_ratio	string / null	"1:1"	Desired aspect ratio (e.g., “16:9”). All outputs are ~1MP total. Supports ratios from 3:7 to 7:3.	No
seed	integer / null	null	Seed for reproducibility. If null or omitted, a random seed is used. Accepts any integer.	No
prompt_upsampling	boolean	false	If true, performs upsampling on the prompt	No
safety_tolerance	integer	2	Moderation level for inputs and outputs. Value ranges from 0 (most strict) to 6 (more permissive).	No
output_format	string	"jpeg"	Desired format of the output image. Can be “jpeg” or “png”.	No
webhook_url	string / null	null	URL for asynchronous completion notification. Must be a valid HTTP/HTTPS URL.	No
webhook_secret	string / null	null	Secret for webhook signature verification, sent in the X-Webhook-Secret header.	No