ComfyUI's standard IMAGE type is optimized for displayable images (range 0.0 ... 1.0), but many signal-processing operations (wavelet coefficients, image differences, high-pass/Sobel/Laplacian filters, ...) naturally produce signed or out-of-range values. This package introduces a lightweight SIGNED_IMAGE convention so those values can be carried through a workflow without being clipped or remapped until you actually want to look at them.

Features

SIGNED_IMAGE: a plain [B,H,W,C] tensor, nominally in -1.0 ... +1.0, zero-centered - not a wrapper type, so any node pack can produce or consume it just by using the same socket type name
Convert IMAGE ↔ SIGNED_IMAGE
Three ways to bring a SIGNED_IMAGE back to 0..1: sign-preserving clamp, magnitude-only (abs), or per-image contrast stretch (minmax)
A one-node preview (Preview Signed Image) that combines the conversion with ComfyUI's own image-preview mechanism

Included Nodes

Convert

To Signed Image
To Unsigned Image
Image Subtract
Preview Signed Image

Sample Workflow

Workflow

workflows/ImageSubtract.json blurs an image (shrink then enlarge with Upscale Image By) and subtracts the blurred version from the original with Image Subtract, producing a signed high-frequency detail map - the classic unsharp-mask setup. Displaying that difference with Preview Signed Image (abs mode here) shows the edge detail that a plain 0..1 subtraction would have clipped away on one side. Load it in ComfyUI and swap in your own image at the Load Image node.

Installation

Clone this repository into your ComfyUI custom_nodes folder.

ComfyUI/
└── custom_nodes/
    └── comfyui-signed-image/

Restart ComfyUI after installation. No extra Python dependencies are required.

SIGNED_IMAGE Data Type

IMAGE
   ↓ To Signed Image
SIGNED_IMAGE
   ↓ signal processing (this package's nodes, or another pack's - e.g. comfyui-wavelet-2d)
SIGNED_IMAGE
   ↓ To Unsigned Image
IMAGE

To Signed Image maps 0.0 ... 1.0 to -1.0 ... +1.0 linearly (signed = image * 2 - 1). To Unsigned Image maps it back, with a choice of clamp (sign-preserving, 0 stays gray), abs (magnitude only, sign discarded), or minmax (per-image contrast stretch, ignores the -1..1 convention entirely).

SIGNED_IMAGE is intentionally just a socket-type name on an ordinary tensor - other node packs (e.g. comfyui-wavelet-2d) can produce and consume it without depending on this package's code.

License

See the repository license file for details.