Viewing Inference Results in a Terminal

Image from the libsixel website.

Motivation

When connecting to a remote machine, normally visualizing image results is not possible or requires moving data to a local device with a GUI. The VSCode integrated terminal allows for directly rendering images. This is a short demonstration on how to use this in conjunction with ultralytics with prediction results.

The VSCode compatible protocols for viewing images using the integrated terminal are sixel and iTerm. This guide will demonstrate use of the sixel protocol.

Process

1. First, you must enable settings terminal.integrated.enableImages and terminal.integrated.gpuAcceleration in VSCode.

   "terminal.integrated.gpuAcceleration": "auto" # "auto" is default, can also use "on"
   "terminal.integrated.enableImages": false
   

1. Install the python-sixel library in your virtual environment. This is a fork of the PySixel library, which is no longer maintained.

   pip install sixel
   

2. Import the relevant libraries

   import io
   
   import cv2 as cv
   
   from ultralytics import YOLO
   from sixel import SixelWriter
   

3. Load a model and execute inference, then plot the results and store in a variable. See more about inference arguments and working with results on the predict mode page.

   from ultralytics import YOLO
   
   # Load a model
   model = YOLO("yolov8n.pt")
   
   # Run inference on an image
   results = model.predict(source="ultralytics/assets/bus.jpg")
   
   # Plot inference results
   plot = results[0].plot() #(1)!
   

   1. See plot method parameters to see possible arguments to use.

4. Now, use OpenCV to convert the numpy.ndarray to bytes data. Then use io.BytesIO to make a "file-like" object.

   # Results image as bytes
   im_bytes = cv.imencode(
       ".png", #(1)!
       plot,
       )[1].tobytes() #(2)!
   
   # Image bytes as a file-like object
   mem_file = io.BytesIO(im_bytes)
   

   1. It's possible to use other image extensions as well.
   2. Only the object at index 1 that is returned is needed.

5. Create a SixelWriter instance, and then use the .draw() method to draw the image in the terminal.

   # Create sixel writer object
   w = SixelWriter()
   
   # Draw the sixel image in the terminal
   w.draw(mem_file)
   

Example Inference Results

Full Code Example

import io

import cv2 as cv

from ultralytics import YOLO
from sixel import SixelWriter

# Load a model
model = YOLO("yolov8n.pt")

# Run inference on an image
results = model.predict(source="ultralytics/assets/bus.jpg")

# Plot inference results
plot = results[0].plot() #(3)!

# Results image as bytes
im_bytes = cv.imencode(
    ".png", #(1)!
    plot,
    )[1].tobytes() #(2)!

mem_file = io.BytesIO(im_bytes)
w = SixelWriter()
w.draw(mem_file)

1. It's possible to use other image extensions as well.
2. Only the object at index 1 that is returned is needed.
3. See plot method parameters to see possible arguments to use.

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