/comfyui-node-outputs

name: comfyui-node-outputs
description: ComfyUI node output types - NodeOutput, UI outputs, PreviewImage, PreviewMask, SavedImages, PreviewAudio, PreviewText, PreviewVideo. Use when returning results from nodes, displaying previews, or saving output files.

ComfyUI Node Outputs

Nodes return data through `io.NodeOutput`. V3 provides built-in UI helpers for previews and file saving.

Basic Output

class SimpleNode(io.ComfyNode):
    @classmethod
    def define_schema(cls):
        return io.Schema(
            node_id="SimpleNode",
            display_name="Simple Node",
            category="example",
            inputs=[io.Float.Input("a"), io.Float.Input("b")],
            outputs=[
                io.Float.Output("SUM"),
                io.Float.Output("PRODUCT"),
            ],
        )

    @classmethod
    def execute(cls, a, b):
        # Values must match output order
        return io.NodeOutput(a + b, a * b)

Output Configuration

io.Schema(
    outputs=[
        io.Image.Output("IMAGE"),                    # basic output
        io.Int.Output("COUNT"),                      # integer output
        io.Float.Output("VALUE", display_name="Result"),  # custom display name
        io.String.Output("TEXT", tooltip="The processed text"),
        io.Image.Output("FRAMES", is_output_list=True),  # outputs a list
    ],
)

NodeOutput Variants

# Data only
return io.NodeOutput(image_tensor, mask_tensor)

# UI only (output node with no data outputs)
return io.NodeOutput(ui=ui.PreviewImage(images, cls=cls))

# Data + UI
return io.NodeOutput(image_tensor, ui=ui.PreviewImage(images, cls=cls))

# No output
return io.NodeOutput()

# Block execution
return io.NodeOutput(block_execution="Reason for blocking")

# Node expansion (positional args are outputs, not result= keyword)
return io.NodeOutput(output_ref, expand=graph.finalize())

UI Preview Helpers

Import `ui` from `comfy_api.latest`:

from comfy_api.latest import io, ui

PreviewImage

Display image previews on the node. Saves to temp directory automatically.

# Constructor: PreviewImage(image, animated=False, cls=None)
class PreviewNode(io.ComfyNode):
    @classmethod
    def define_schema(cls):
        return io.Schema(
            node_id="PreviewNode",
            display_name="Preview Image",
            category="image",
            is_output_node=True,
            inputs=[io.Image.Input("images")],
            outputs=[],
            hidden=[io.Hidden.prompt, io.Hidden.extra_pnginfo],
        )

    @classmethod
    def execute(cls, images):
        return io.NodeOutput(ui=ui.PreviewImage(images, cls=cls))

PreviewMask

# Constructor: PreviewMask(mask, animated=False, cls=None)
# Auto-converts mask to 3-channel grayscale for display
return io.NodeOutput(ui=ui.PreviewMask(masks, cls=cls))

PreviewAudio

# Constructor: PreviewAudio(audio, cls=None)
# Saves as FLAC to temp directory
return io.NodeOutput(ui=ui.PreviewAudio(audio, cls=cls))

PreviewVideo

# Constructor: PreviewVideo(values: list[SavedResult | dict])
return io.NodeOutput(ui=ui.PreviewVideo(saved_video_results))

PreviewText

Display text output:

return io.NodeOutput(ui=ui.PreviewText(value))

PreviewUI3D

Display 3D model preview:

return io.NodeOutput(ui=ui.PreviewUI3D(
    model_file=saved_result,   # SavedResult for the 3D file
    camera_info=camera_dict,   # camera position/target/zoom
    bg_image=image_tensor,     # optional background image (via **kwargs)
))

PreviewUI3DAdvanced

3D preview that also carries per-model transforms (used by the Preview3DAdvanced node):

return io.NodeOutput(ui=ui.PreviewUI3DAdvanced(
    model_file=saved_result,
    camera_info=camera_dict,       # supports extended CameraInfo (quaternion/fov/near/far/frustum)
    model_3d_info=transforms,      # list[Model3DTransform]: position/quaternion/scale per model
))

Saving Images

Using ImageSaveHelper

The `ui.ImageSaveHelper` class provides static methods for various image formats:

# Save as PNG (returns list[SavedResult])
results = ui.ImageSaveHelper.save_images(
    images,                              # tensor [B,H,W,C]
    filename_prefix="ComfyUI",
    folder_type=io.FolderType.output,    # output, temp, or input
    cls=cls,                             # node class (for metadata)
    compress_level=4,
)

# Save and get UI object directly (saves to output folder)
saved_ui = ui.ImageSaveHelper.get_save_images_ui(images, "ComfyUI", cls=cls)
return io.NodeOutput(ui=saved_ui)

# Save animated PNG
result = ui.ImageSaveHelper.save_animated_png(
    images, "anim", io.FolderType.output, cls=cls, fps=12.0, compress_level=4
)

# Save animated PNG and get UI
saved_ui = ui.ImageSaveHelper.get_save_animated_png_ui(images, "anim", cls=cls, fps=12.0, compress_level=4)

# Save animated WebP
result = ui.ImageSaveHelper.save_animated_webp(
    images, "anim", io.FolderType.output, cls=cls,
    fps=12.0, lossless=False, quality=80, method=4
)

# Save animated WebP and get UI
saved_ui = ui.ImageSaveHelper.get_save_animated_webp_ui(
    images, "anim", cls=cls, fps=12.0, lossless=False, quality=80, method=4
)

**Simple save node example:**

class SaveImageNode(io.ComfyNode):
    @classmethod
    def define_schema(cls):
        return io.Schema(
            node_id="SaveImageNode",
            display_name="Save Image",
            category="image",
            is_output_node=True,
            inputs=[
                io.Image.Input("images"),
                io.String.Input("filename_prefix", default="ComfyUI"),
            ],
            outputs=[],
            hidden=[io.Hidden.prompt, io.Hidden.extra_pnginfo],
        )

    @classmethod
    def execute(cls, images, filename_prefix):
        saved = ui.ImageSaveHelper.get_save_images_ui(images, filename_prefix, cls=c