Image to Image - Qwen i2i
Hi, I’ve been testing img2img (image-to-image) with Qwen-Image in ComfyUI and found a consistent issue:
When starting from a pure noise latent, the generation works as expected: detailed, sharp, and visually consistent.
When starting from an encoded latent (VAE Encode of an input image), the output often looks washed out / watercolor-like, and in many cases exhibits visual artifacts or partially broken images, even at higher denoise values.
This does not happen when I use the same workflow with other models (e.g., Flux), where img2img from an encoded latent preserves or improves detail without breaking.
Steps to Reproduce:
Load Qwen-Image FP8/BF16 (also tested with distilled).
Use official Qwen VAE for both encoding and decoding.
Encode a real image → VAE Encode → KSampler (img2img).
Settings tested:
Sampler: Euler / Res_multistep
Scheduler: Simple / Beta
Steps: 28–36 (FP8/BF16), 10–15 (distilled)
CFG: 1–6 (FP8/BF16), 1.0 (distilled)
Denoise: 0.25–0.6
ModelSamplingAuraFlux shift: 1–3.1
Compare outputs:
Case A: latent = pure noise (same seed) → sharp, detailed, artifact-free. :)
Case B: latent = VAE Encode of an image → watercolor-like texture and sometimes broken visuals (patchy areas, corrupted colors, loss of structure) :(
Observed Behavior:
From encoded latents:
Loss of high-frequency detail (watercolor/plastic look)
Structural artifacts (patchy regions, color corruption, distorted geometry)
Is there a known limitation or workaround for Qwen-Image when doing img2img from encoded latents?
Can you help me? Thanks in advance!
Hi, can you show your workflow?
Hi, can you show your workflow?
Hi etaooo, I attach the json
JSON = https://pastebin.com/f5WCsPdx
I also tested the MaskPaint node and it shows the same problem.
For me, MaskPaint is very important because I use it to add fine details in specific areas such as the face, eyes, hands, etc.
Regards
Hi, can you show your workflow?
Hi etaooo, I attach the json
JSON = https://pastebin.com/f5WCsPdx
I also tested the MaskPaint node and it shows the same problem.
For me, MaskPaint is very important because I use it to add fine details in specific areas such as the face, eyes, hands, etc.Regards
I did some testing with fp8 and here is the result, ( Iuse dpmpp_2s_ancestral and ddim_uniform [Normal is better for text tho] )