immdebug

Visual image debugger for Python — inspect images from any running process with zoom, pan, pixel values, and colormaps.

Part of the immvision / Dear ImGui Bundle ecosystem.

Install

pip install immdebug

This installs both the client (for sending images) and the viewer (for displaying them).

Quick start

1. Start the viewer (in a terminal):

immdebug-viewer
# or: python -m immdebug

2. Send images (from your code, a script, a notebook, ...):

import numpy as np
from immdebug import immdebug

image = np.random.randint(0, 255, (480, 640, 3), dtype=np.uint8)
immdebug(image, "random noise")

The image appears in the viewer immediately.

How it works

immdebug() serializes the image to a temp directory (<tempdir>/ImmDebug/). The viewer polls this directory and displays incoming images using immvision's inspector.

This is the same protocol used by the C++ ImmDebug() function, so the Python client works with both the Python and C++ viewers.

Use with OpenCV

OpenCV uses BGR channel order. Use immdebug_bgr for correct colors:

import cv2
from immdebug import immdebug, immdebug_bgr

image = cv2.imread("photo.jpg")
immdebug_bgr(image, "original")  # BGR image from OpenCV

gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
immdebug(gray, "grayscale")  # single-channel, order doesn't matter

edges = cv2.Canny(gray, 100, 200)
immdebug(edges, "edges")

Use with PIL, matplotlib, etc.

Most other libraries (PIL/Pillow, matplotlib, stb) use RGB order. Use immdebug (the default):

from PIL import Image
from immdebug import immdebug
import numpy as np

image = np.array(Image.open("photo.jpg"))
immdebug(image, "original")

API

def immdebug(image, legend="", zoom_center=(0.0, 0.0), zoom_ratio=-1.0,
             zoom_key="", color_adjustments_key="") -> None:
    """Send an RGB image to the viewer."""

def immdebug_bgr(image, legend="", zoom_center=(0.0, 0.0), zoom_ratio=-1.0,
                 zoom_key="", color_adjustments_key="") -> None:
    """Send a BGR image (OpenCV) to the viewer."""

Features

• Non-blocking: immdebug() just writes a file and returns immediately
• Post-mortem: images persist in the temp directory for 1 hour — start the viewer after your script finishes
• Single instance: launching a second viewer brings the existing one to the front
• Cross-language: works with both the Python and C++ immdebug viewers

License

MIT