Variable Image Builder

Sometimes you don't need a good image, you just need an image. Variable Image Builder makes solid-color RGB images at a size, color, and batch count you choose. It won't generate anything artistic - it's a factory for flat rectangles - and that's precisely its use: placeholder data, pipeline testing, or forcing an image input to a known state when you're debugging the plumbing around it.

The inputs are straightforward: r, g, b, a (each 0–255), width (default 512), height (default 512), and batch_size (default 1). The one output is Image, a single IMAGE tensor - which, importantly, contains batch_size copies of the color stacked together, not a list of images. If you want a list of images you'd split it downstream.

A couple of details worth knowing before you wire it up:

• The color inputs are marked so they can take a wire (defaultInput), meaning you can drive the color from another node rather than only typing it. So yes, you could build a tiny color-swatch tool by feeding it different values per batch - but note it takes single values, not lists, so a genuine color sweep still means looping at the graph level.
• The a input is alpha, and here's the quiet lie in the interface: the output is RGB, and Pillow happily accepts the 4-tuple and just drops the alpha. Setting a=0 does not give you transparency, because RGB has no alpha channel to put it in. It's harmless, but don't go hunting for a transparent image that isn't coming.

Where does a flat color image actually earn its keep? Debugging. If a workflow produces nothing and you're not sure whether the problem is your sampler or your image chain, a known solid color tells you fast whether the pipeline is even moving pixels. It's also handy for placeholder composition when you're laying out a grid and want the geometry right before you spend GPU time on real content. For the pack's grid tools, it's a way to populate Empty Images-style placeholders with a color you actually chose, rather than the auto-generated rainbow the Empty Images node cycles through.

It's a small node, and the honest review is that its usefulness is proportional to how much you debug and template workflows. Regular generation? You'll rarely touch it. Building and testing graphs? It's nice to have.

Install is the pack standard - no dependencies to pip, no models to fetch:

cd ComfyUI/custom_nodes
git clone https://github.com/M1kep/Comfy_KepListStuff

Restart ComfyUI (or install Comfy_KepListStuff via Manager) and it's under List Stuff. Pick a color, set a size, and get your flat rectangle on demand.