NB2 Smart Region

NB2 Crop wants a rectangle. Florence-2 and SAM give you an organic blob. NB2 Smart Region is the adapter: it takes a semantic mask - from NB2Florence2RegionSelector, NB2SAM3ImageSegmenter, kijai's Florence2Run, or any segmentation node - and fits the tightest Nano Banana-sized rectangle around it, expanding, padding, and aspect-correcting so the downstream crop and stitch stay in lockstep.

It's the node you reach for when you want the convenience of "click a semantic region, let the model find it" but still want to run the manual NB2 crop/stitch path. The README's recommended flow puts it right in the middle:

NB2Florence2RegionSelector or Florence2Run (kijai) -> mask
    -> NB2 Smart Region -> NB2 Crop -> Nano Banana 2 Edit -> NB2 Stitch

Inputs

Required: image, region_mask (the semantic mask), and the shape controls:

• aspect_ratio - defaults to auto, which is the interesting one. In auto mode the node first checks the Florence region metadata (via region_info) for a shape hint - face → 1:1, glasses → 16:9, full body → 9:16 - and falls back to the mask's bounding box if there's no hint. Otherwise you can force 16:9 / 9:16 / 1:1.
• resolution (1K, 2K, 4K) - generation budget, and it needs to match what you set on NB2 Crop.
• padding_percent (default 8) - expands the detected region before rectangle fitting, so the model gets breathing room around the object. Faces want more (10–18 per the README), small objects less (5–12).
• crop_scale (1.0–4.0) - an extra scale multiplier applied after the aspect fit. Handy when you want to zoom the crop out further than padding alone.
• depad_florence (default True) - here's a real trap worth understanding. Florence-2 letterboxes images to a square internally before processing, which shifts the detected bbox on non-square images. Keep this True when the mask came from Florence (Florence2Run / this pack's selector) to correct for that. Set it False only when your mask is already at exact source resolution - a hand-drawn mask or a SAM output, for example.
• region_info - optional, the info string from the selector. Feed it in and aspect_ratio = auto can use the region's shape hint.

Outputs: mask (the fitted rectangle, into NB2 Crop), nb2_width/nb2_height, preview_image (source with the rectangle drawn on - wire it to a Preview node, it's your sanity check), plus center_x/center_y/crop_width/crop_height and info for scripting.

The depad trap in practice

Most "why is my crop off to one side?" reports in this pack trace back to depad_florence. If you run Florence-2 locally via kijai's pack, the mask arrives with the internal square padding baked in, and without depadding the rectangle lands shifted - the README explicitly calls this out. Keep the default True for Florence masks, flip to False for SAM or hand-drawn ones, and the rectangle lands where the region actually is.

Install

One pack, all nodes:

cd ComfyUI/custom_nodes
git clone https://github.com/amortegui84/comfyui-inpaint-cropstitch-nb2

or search comfyui-inpaint-cropstitch-nb2 in ComfyUI Manager, restart. This node itself is local and keyless - the selector upstream (if you use this pack's FAL one) and the edit node downstream are the parts that need FAL_KEY.