Is Not Null (Image)

I'll tell you the uncomfortable truth about SL_IsNotNullImage before the sales pitch, because there isn't one: as it's wired in this pack, it almost always returns True. The node's entire job is to check whether the input image is None and return a boolean - the code is literally image is not None - but ComfyUI doesn't hand out None to required inputs. If you don't wire the image port, the queue refuses to run. If you do wire it, you've connected a real image tensor, which is by definition not None. So the check is... always true.

That sounds like damning it, and for the 95% case it is. But there's a narrow world where this node is exactly what you want: ComfyUI's wildcard type (*) chains. Some packs let a node pass a None value through a wildcard output - a switch that can hand you "nothing" instead of an image. In that scenario, this node becomes a real gate: downstream logic can ask "is there actually an image here, or did a branch yield nothing?" before proceeding. That's the pattern the author was clearly aiming at - the node exists for the nullable case that ComfyUI's strict typing mostly prevents you from constructing.

Inputs and outputs:

• image (IMAGE) - the image to check. No default; it must be wired.
• Output: BOOLEAN - True if an image is present, False if it's None.

Installing it

Part of ComfyUI-SimpleLogics. Manager → search "SimpleLogics" → install → restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/danipisca07/ComfyUI-SimpleLogics

Restart, Add Node → search "Is Not Null" (menu group SimpleLogics/Logic). Zero dependencies, no models.

How to actually use it

Honestly: only inside a wildcard chain where None can genuinely flow. If your source is a normal Load Image or a sampler output, skip this node - it adds a tautology to your graph, not a condition. The sibling SL_IsNotNullText has the same limitation but worse (its text input has a default "", so it can never be None). If your goal is "did this branch produce something," the more robust pattern is to compare against a sentinel or restructure the switch logic instead of relying on null-ness that ComfyUI won't let you create.

If you came here hoping for a "check the image loaded successfully" node - the instinct is right, but this isn't quite that tool. Wire it from a wildcard source if you must; otherwise treat it as a node whose honest answer is "yes," every time.