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Update README with example and t_min/max format info

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2024-03-17 16:19:54 -06:00
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@@ -14,11 +14,56 @@ git clone https://github.com/ssitu/ComfyUI_restart_sampling
## Usage
Nodes can be found in the node menu under `sampling`:
The Restart sampler nodes can be found in the node menu under `sampling`.
### Nodes
|Node|Image|Description|
| --- | --- | --- |
| KSampler With Restarts | ![image](https://github.com/ssitu/ComfyUI_restart_sampling/assets/57548627/7696da21-ea8c-4263-91a9-658d0f87dc47) | Has all the inputs of a KSampler, but with an added string widget for configuring the Restart segments and a widget for the scheduler for the Restart segments. Not all samplers and schedulers from KSampler are currently supported. Restart sampling is done with ODE samplers and are not supposed to be used with SDE samplers. <br>The format for `segments` is a sequence of comma separated arrays of ${[N_{\textrm{Restart}}, K, t_{\textrm{min}}, t_{\textrm{max}}]}$. For example, [4, 1, 19.35, 40.79], [4, 1, 1.09, 1.92], [4, 5, 0.59, 1.09], [4, 5, 0.30, 0.59], [6, 6, 0.06, 0.30] would be a valid sequence. Segments may overwrite each other if their $t_{\textrm{min}}$ parameters are too close to each other. Each segment will add $(N_{\textrm{Restart}} - 1) \cdot K$ steps to the sampling process. For more information on the Restart parameters, refer to the paper. <br>The `restart_scheduler` is used as the scheduler for the denoising process during restart segments. The researchers used the Karras scheduler in their experiments, but use the same scheduler as the sampler schedule in their implementation. |
| KSampler With Restarts | ![image](https://github.com/ssitu/ComfyUI_restart_sampling/assets/57548627/7696da21-ea8c-4263-91a9-658d0f87dc47) | Has all the inputs of a KSampler, but with an added string widget for configuring the Restart segments and a widget for the scheduler for the Restart segments. Not all samplers and schedulers from KSampler are currently supported. Restart sampling is done with ODE samplers and are not supposed to be used with SDE samplers. <br>See the [Segments](#segments) section below for information how to define segments. For more information on the Restart parameters, refer to the paper. <br>The `restart_scheduler` is used as the scheduler for the denoising process during restart segments. The researchers used the Karras scheduler in their experiments, but use the same scheduler as the sampler schedule in their implementation. |
| KSampler With Restarts (Simple) | | Instead of having a restart segment scheduler, segments will use the same scheduler as the KSampler scheduler. |
| KSampler With Restarts (Advanced) | | Has all the inputs for an Advanced KSampler with all the inputs for restart sampling. It should be noted that there is a possibility for invalid segments when using it to end the denoising process early or starting it late (e.g. 20 steps, start at step 0, end at step 10) and invalid segments will be ignored. An invalid segment means that the closest $t_{\textrm{min}}$ in the noise schedule is higher than the segment's $t_{\textrm{max}}$, so the segment would have restarted the denoising process at $t_{\textrm{max}}$ then try to go to a higher noise level (when it should've gone to a lower noise level near $t_{\textrm{min}}$) which will destroy the sample. |
| KSampler With Restarts (Custom) | | Essentially the same as `KSampler With Restarts (Advanced)` but it takes a `SAMPLER` input like the built in `SamplerCustom` node. Note that it is possible to input samplers that don't work properly or are incompatible with Restart sampling like SDE samplers and UNI PC|
| KSampler With Restarts (Custom) | | Essentially the same as `KSampler With Restarts (Advanced)` but it takes a `SAMPLER` input like the built in `SamplerCustom` node. Note that it is possible to input samplers that don't work properly or are incompatible with Restart sampling like SDE and UniPC samplers.|
### Segments
The format for `segments` is a sequence of comma separated arrays of ${[N_{\textrm{Restart}}, K, t_{\textrm{min}}, t_{\textrm{max}}]}$. For example, `[4, 1, 19.35, 40.79], [4, 1, 1.09, 1.92], [4, 5, 0.59, 1.09], [4, 5, 0.30, 0.59], [6, 6, 0.06, 0.30]` would be a valid sequence. Segments may overwrite each other if their $t_{\textrm{min}}$ parameters are too close to each other. Each segment will add $(N_{\textrm{Restart}} - 1) \cdot K$ steps to the sampling process.
Both $t_{\textrm{min}}$ and $t_{\textrm{max}}$ within a segment definition may be specified in any of the following three ways:
* A positive numeric value (i.e. `1.2`) — this will be interpreted as a sigma value.
* A negative numeric value between `-0` and `-1000` — this will be interpeted as a (positive) timestep. Timesteps will be converted to integer values so if you need to specify timestep `0` you can do something like `-0.1`.
* A quoted string percentage value followed by a percent sign (i.e. `"25%"`) — note that this refers to the percentage of sampling, not the percentage of steps that have elapsed.
You may freely mix the different formats. For example, `[2, 2, -500, "10%"], [3, 2, 5.3, -3]` would be a valid sequence. Note: Random numbers used for example only, not recommended.
## Visual Example
Consider the default segments of `[3,2,0.06,0.30],[3,1,0.30,0.59]`.
1. $N_{\textrm{Restart}}=3, {K}=2, t_{\textrm{min}}=0.06, t_{\textrm{max}}=0.30$ — closer to the end of sampling, will run two restarts two times.
2. $N_{\textrm{Restart}}=3, {K}=1, t_{\textrm{min}}=0.30, t_{\textrm{max}}=0.59$ — closer to the beginning of sampling, will run two restarts one time.
Running 20 steps with normal scheduling will look something like this:
```plaintext
Step 1: sigma=10.7
Step 2: sigma=8.08
Step 3: sigma=6.2
[... elided for brevity]
Step 15: sigma=0.596
Step 16: sigma=0.474
Step 17: sigma=0.356 -- [3,1,0.30,0.59] matches here.
K=1:
restart 1, step 18
restart 2, step 19
Step 20: sigma=0.232
Step 21: sigma=0.0292 -- [3,2,0.06,0.30] matches here.
K=1:
restart 1, step 22
restart 2, step 23
K=2:
restart 1, step 24
restart 2, step 25
Step 26: sigma=0.0
```