Sampling Methods
Different Sampling methods can create different results on the same prompt at different step values. Some may create very similar images and others won't.
We've picked k_euler_ancestral as our standard for regular resolutions up to 1024 x 1024 pixels, due to its consistent, high-quality generations in combination with NovelAI Diffusion. We highly recommend leaving this setting as is, unless you have a deeper knowledge of Image Generation.
NovelAIDiffusion Image Generation Samplers: nai_smea & nai_smea_dyn
What is nai smea?
Sinusoidal Multipass Euler Ancestral (smea) is a new sampler we have developed with the goal of improving overall coherency and quality, especially at higher resolutions. Based on the Euler ancestral sampler, we create a new sine-based schedule that interpolates between multiple passes of the regular diffusion model as sampling progresses. This approach ensures that SD attends to both local and global features. Oftentimes when sampling at higher resolutions with the conventional samplers, SD can produce repeats of the same subjects or bizarre anatomy, this is largely due to poor global attention at higher resolutions, and smea aims to solve that.
nai_smea & nai_smea_dyn are perfect for higher resolutions!
Difference between nai_smea & nai_smea_dyn The differences between the two new samplers are most obvious when higher image resolutions are used. nai_smea_dyn focuses less time on lower generations and begins to shine dynamically in the mid to high range of a generation. We've noticed slightly more refined compositions. Ultimately, the effectiveness of each sampler will depend on the specific use case and image resolution.
Pricing: Why is nai smea more expensive? nai_smea runs multiple passes of the unet during each step, it costs slightly more than the other samplers based on the increased compute cost, the increase is relative to the increased amount of time it takes the GPU to process a request.
Auto nai_smea Toggle Option
We've even added a nifty option to Auto Apply nai_smea for images over 1024x1024 and above pixels. You can toggle this setting as needed - so you still have the option to experiment to your heart's content with other samplers!
Tips:
The nai-smea & nai_smea_dyn sampler generations vary between the different Step and Scale counts.
The nai_smea & nai_smea_dyn sampler Scale values can go much higher before becoming unpredictable. You may want to increase the Scale value if you are generating at higher resolutions.
If you have a particularly short prompt that seemingly performs badly please try copy-pasting it into the prompt field repeatedly. We've noted that this can solve issues during testing.
Sometimes the sampler may focus on different aspects of your prompt that differ from the previous defaults: You can alleviate this with emphasis and de-emphasizing aspects of your prompt. (https://docs.novelai.net/image/strengthening-weakening.html)
We recommend experimentation to find your preferred values with samplers!
Nai Smea Comparison Samples
