ausboss
13145ed881
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".
69 lines
3.4 KiB
Markdown
69 lines
3.4 KiB
Markdown
# Step Preview
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Shows the picture while it is being made, one step at a time, with a
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**Stop** button. If the picture is going wrong (the pose, the framing, an
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extra arm) you can see it after the first few steps and stop the run,
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instead of waiting for the last step.
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Put it anywhere on the canvas. It needs no wires: it shows whichever sampler
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in the workflow is making a picture right now, and the caption under the
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picture says how far it is ("step 3 of 8").
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## The buttons
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- **STOP**: stops this run now. Nothing after the sampler runs, so nothing
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is saved. The next run in the queue still starts.
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- **STOP ALL · N**: shows when more runs are waiting in the queue. It
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empties the queue and stops this run.
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As soon as the run saves the picture, the finished picture replaces the
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blurry last step, and it stays on the node until the next run starts. The
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word at the right of the bar says how the run ended: done, stopped or
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failed. A stopped run keeps the last step it reached.
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An upscale in tiles works on one small piece of the picture at a time.
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Those pieces are not shown as the picture: the node keeps the last whole
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picture and says "upscaling in tiles", with the steps of the piece being
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worked on.
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## Save Image and Save Video can do it too
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Save Image 🆎 and Save Video 🆎 have a **steps** switch of their own (off by
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default). On, the picture area of the save node shows the steps of the
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picture it is about to save, with the same Stop button. Use the save node's
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switch when you look at the result anyway, and this node when you want a
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bigger view, or one view for a workflow with several samplers.
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## Sharper step pictures
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The step pictures are small and blurry. That is enough to judge the pose
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and the layout. Some models have a small preview decoder (a TAESD file)
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that makes them sharper: put it in ComfyUI's `models/vae_approx` folder and
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ComfyUI uses it.
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## Technical details
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- ComfyUI only makes step pictures when its preview method is something
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other than `none`, and a fresh install starts with `none`. When a queued
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workflow holds this node, or a Save Image or Save Video with its steps
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switch on, the pack asks for the `auto` method for that one run.
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- It never overrides a choice you made: if you picked a method in
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ComfyUI's **Live preview method** setting, or started ComfyUI with
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`--preview-method`, that one is used. `--preview-method none` on the
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command line is treated as "not chosen", since it is the default.
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- `auto` uses the model's TAESD decoder from `models/vae_approx` when it is
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installed, and a quick color estimate (latent2rgb) otherwise. Some models
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have neither (SeedVR2, for one), and then no step pictures come.
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- The pictures are at most 512 px on their long side (`--preview-size`).
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They do not change the result: the same seed makes the same picture with
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the steps shown or not.
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- They cost next to nothing. Measured with Qwen Image 2.1 on one desktop:
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8.50 s with the steps off and 8.40 s on for 8 steps, 17.62 s and 17.64 s
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for 25 steps, the same picture every time.
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- While previews are on, a ComfyUI sampler that sits on the top level of
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the workflow (not inside a box) shows the steps on its own face too, as
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it does whenever previews are turned on in ComfyUI. The node grows to
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hold the picture and keeps the last step after the run.
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- Runs queued from another workflow tab are not shown here.
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- With video models the step picture is the clip's first frame.
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