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ausboss 13145ed881 Save Image: say a run is going, hold the last step, keep tiles off the picture

While the models load, an empty picture area says the run is going instead
of asking for a run. With steps on, the last step stays up until the saved
picture has loaded, so it no longer blinks out. Between a tiled upscale's
split and stitch (and for Ultimate SD Upscale) the step pictures are tiles:
the whole picture stays and the chip says "upscaling in tiles".

2026-10-27 08:51:40 -05:00

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Step Preview

Shows the picture while it is being made, one step at a time, with a Stop button. If the picture is going wrong (the pose, the framing, an extra arm) you can see it after the first few steps and stop the run, instead of waiting for the last step.

Put it anywhere on the canvas. It needs no wires: it shows whichever sampler in the workflow is making a picture right now, and the caption under the picture says how far it is ("step 3 of 8").

The buttons

STOP: stops this run now. Nothing after the sampler runs, so nothing is saved. The next run in the queue still starts.
STOP ALL · N: shows when more runs are waiting in the queue. It empties the queue and stops this run.

As soon as the run saves the picture, the finished picture replaces the blurry last step, and it stays on the node until the next run starts. The word at the right of the bar says how the run ended: done, stopped or failed. A stopped run keeps the last step it reached.

An upscale in tiles works on one small piece of the picture at a time. Those pieces are not shown as the picture: the node keeps the last whole picture and says "upscaling in tiles", with the steps of the piece being worked on.

Save Image and Save Video can do it too

Save Image 🆎 and Save Video 🆎 have a steps switch of their own (off by default). On, the picture area of the save node shows the steps of the picture it is about to save, with the same Stop button. Use the save node's switch when you look at the result anyway, and this node when you want a bigger view, or one view for a workflow with several samplers.

Sharper step pictures

The step pictures are small and blurry. That is enough to judge the pose and the layout. Some models have a small preview decoder (a TAESD file) that makes them sharper: put it in ComfyUI's models/vae_approx folder and ComfyUI uses it.

Technical details

ComfyUI only makes step pictures when its preview method is something other than none, and a fresh install starts with none. When a queued workflow holds this node, or a Save Image or Save Video with its steps switch on, the pack asks for the auto method for that one run.
It never overrides a choice you made: if you picked a method in ComfyUI's Live preview method setting, or started ComfyUI with --preview-method, that one is used. --preview-method none on the command line is treated as "not chosen", since it is the default.
auto uses the model's TAESD decoder from models/vae_approx when it is installed, and a quick color estimate (latent2rgb) otherwise. Some models have neither (SeedVR2, for one), and then no step pictures come.
The pictures are at most 512 px on their long side (--preview-size). They do not change the result: the same seed makes the same picture with the steps shown or not.
They cost next to nothing. Measured with Qwen Image 2.1 on one desktop: 8.50 s with the steps off and 8.40 s on for 8 steps, 17.62 s and 17.64 s for 25 steps, the same picture every time.
While previews are on, a ComfyUI sampler that sits on the top level of the workflow (not inside a box) shows the steps on its own face too, as it does whenever previews are turned on in ComfyUI. The node grows to hold the picture and keeps the last step after the run.
Runs queued from another workflow tab are not shown here.
With video models the step picture is the clip's first frame.

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