ProPostRadialBlur

Sometimes you want that shallow-depth-of-field look - sharp subject, soft everything else - but you don't have a depth map handy and don't want to run one just to blur some edges. ProPostRadialBlur is the shortcut: it blurs the image based purely on distance from a point you pick, no depth estimation involved. Think of it as a fake lens, not a real one - it assumes "far from the center" means "should be blurry," which is true often enough to be genuinely useful and wrong often enough that you should know when to reach for its sibling node instead.

How it works

The node measures every pixel's distance from center_x/center_y and blurs it more the farther away it is, ramping the blur strength outward. focus_spread controls how wide the sharp zone in the middle is before the blur kicks in, and steps controls how many passes the blur takes - more steps means a smoother gradient from sharp to blurry, at the cost of speed.

This is a genuine trade against ProPostDepthMapBlur, its sibling in the pack: radial blur has no idea what's actually near or far in the scene, it only knows what's near or far from a 2D point in the frame. For a centered portrait shot that's often close enough. For anything with real depth complexity - a person off to one side, foreground objects, an interior with multiple depth planes - it'll blur things that should be sharp and vice versa, because it's working off frame position, not scene geometry.

The inputs that matter

• blur_strength (default 64.0, range 0.0–256.0) - how intense the blur gets at the edges. This is the main dial.
• center_x / center_y (both default 0.5) - where the sharp zone is centered, as a fraction of the frame. Move this to wherever your subject actually is.
• focus_spread (default 1.0, range 0.1–8.0) - how much of the image around the center stays sharp before blur ramps in. Higher values keep more of the frame in focus.
• steps (default 5) - blur quality. The README calls out one specific trick here: set steps to 1 with a high blur_strength and you get a distinct dreamy, almost double-exposure look rather than a clean gradient blur - a deliberate stylistic use of what would otherwise look like an artifact.

One image in, one IMAGE out.

Installing it

ComfyUI Manager: search propost, install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/digitaljohn/comfyui-propost.git
pip install -r requirements.txt

Full restart of ComfyUI required - not just a browser reload.

Where people get tripped up

The main trap is reaching for this when what you actually need is Depth Map Blur. If your subject isn't roughly centered, or the scene has real foreground/background separation you want respected, radial blur will fight you - it'll happily blur part of your subject just because it's off-center, and leave background clutter sharp just because it's near the middle of the frame. Recenter with center_x/center_y first; if that still doesn't get you a clean result, that's the signal to switch nodes rather than keep raising blur_strength.

The other thing worth knowing: steps past 5 or so gets slow for not much visible gain on most images - the blur gradient is already smooth by then. Save the higher step counts for large or high-resolution outputs where banding in the blur transition is actually visible.