🐙 Kraken Empty Latent Image

The stock Empty Latent Image gives you two numbers and a prayer. 🐙 Kraken Empty Latent Image is what you use when you're tired of doing the "is 1080x1920 really 9:16, and what's that in a latent" arithmetic on every workflow. It's a drop-in latent creator with 39 aspect-ratio presets organized the way real humans think - phone screens, cinema ratios, Instagram, Full HD, 4K - plus megapixel-driven sizing, and it hands your chosen resolution out as strings you can wire into the rest of the Kraken pack's upscaling math.

It's one node in Kraken Tools (krakenunbound/comfyui-kraken-tools), and it's the front end of the pack's resolution story: it computes a size, then Kraken Preset From Image and the upscale calculator pick up that same preset_out string so your resize targets and your latent agree without you typing a resolution twice.

How it works

You pick two things and it does the math. megapixel (0.5 to 3.0, plus Custom) is the total pixel budget; preset is the aspect ratio. The node multiplies the budget by the ratio, resolves to concrete width/height, and snaps both to divisible_by - the Auto default picks a multiple appropriate for the size, or you can force 8/16/32/64/128/256. This matters more than it sounds: SDXL models were trained around 1024-ish totals, and WAN/Flux video want latents that divide cleanly for their VAEs. A latent that's off by a pixel in either dimension is a classic source of "why is my video slightly smeared" weirdness.

The presets are grouped the way you'll actually look for them: portrait (9:20, 9:16, 2:3, 3:4, 4:5), square, landscape (up to 16:9), cinematic (1.85:1, 2:1, 21:9, 2.39:1), plus named screen sizes (Android, iPhone, Full HD, 4K) and social slots (Instagram, YouTube, Facebook). For anything not in the list, flip use_custom_aspect and type custom_aspect like 7:5, then let width/height handle the fine detail.

The only inputs most people touch:

• megapixel - the total pixel budget
• preset - the aspect ratio
• divisible_by - the alignment multiple
• batch_size - how many identical latents to make (1 is normal; more is for batch/video work)

Outputs

• latent → your sampler's latent_image.
• width_out / height_out (INT) - the resolved dimensions, for any node that needs numbers.
• resolution (STRING) - e.g. "1024 x 1024", handy for text display.
• preset_out (STRING) - the same resolution as a "WxH" string, designed to feed Kraken Resolution Helper / Kraken Upscale & Tile Calc in the same pack. This is the output that makes the "empty latent → upscale calculator" chain work without retyping numbers.

There's also an enable_preview optional that renders a small placeholder image preview of the canvas (cap the size with max_preview_size) - pure UI nicety, no effect on the latent.

Install

Standard Kraken Tools install. ComfyUI Manager → search "Kraken Tools" → Install → restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/krakenunbound/comfyui-kraken-tools
cd comfyui-kraken-tools
pip install -r requirements.txt

Restart and you'll find it under the Kraken category. No extra model files - this node is pure math and Pillow.

Where people get burned

• Megapixel + ratio = chunky dimensions. 2.5MP at 21:9 is a lot of pixels on a normal card; if you're on 8GB, don't assume the preset will "just work" at high megapixels. Drop to 1.0–1.5 for cinematic ratios.
• Custom in megapixel means width/height take over. If you set megapixel to Custom you're now driving from the width/height sliders, and the preset is advisory. Easy to forget mid-workflow.
• The preview is not the image. enable_preview shows a colored placeholder rectangle, not your render. People occasionally wire the wrong output to a Save node and save a blank block of color - the actual image always comes out of the sampler, not this node.

If you generate at the same three ratios over and over, presets save you maybe ten seconds a run. If you're building upscaling chains that need resolution math flowing between nodes, preset_out is the piece that makes the whole thing coherent.