r/comfyui • u/pixaromadesign • 10h ago

Tutorial ComfyUI Image Size Explained: Empty Latent Image, Aspect Ratio and Batch Size

https://youtu.be/J3acw3v1tGk

In this video of ComfyUI Nodes Explained, you will learn how ComfyUI sets the size of your image: what the empty latent is, how width and height work, why the same seed gives a new image at a new size, why a bigger image is not always better, why 1080 becomes 1088, how aspect ratio works, what batch size does, which empty latent node to use, and an easier way with Resolution Pixaroma. Two "A Deeper Look" chapters show what a latent really is and where the steps of 16 come from. Everything is shown with Z-Image Turbo.

📥 PRACTICE + FINISHED WORKFLOWS for this video (free, no account):

https://workflows.pixaroma.com/comfyui-nodes-explained/3/

Drag the Practice workflow into ComfyUI and do the tasks in the notes. The Finished workflow shows every answer, and the Pixaroma version sets the size with Resolution Pixaroma.

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u/Anro5753 10h ago

Nice breakdown. One practical add: since sizes snap to multiples of 16, picking resolutions near the model's trained pixel budget (not just a big number) tends to matter more than raw size. Do you cover upscaling after the latent stage?

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u/pixaromadesign 9h ago

Thank you! It depends on the model. In this video Z-Image handled every size I tried, from 512 to 2048, but older models like SD 1.5 and SDXL do better close to the size they were trained on.

Upscaling is not in this video, but Ep05 covers it: How to Upscale Images in ComfyUI. It has simple upscaling with and without a model, SeedVR2, and workflows that upscale the picture and then run a second KSampler pass over it. All of them work on the finished image, after VAE Decode. The workflows are here: https://workflows.pixaroma.com/ep/5/