FLUX.2-Klein, Qwen Image, and Z-Image Turbo: an 18-run ComfyUI test

I wanted a small answer to a practical question: with the three closest image models already installed on one 24 GB laptop GPU, which one can actually make a quiet hand-painted mountain-cabin shot—and then preserve an illustrated two-character scene—without help from a LoRA?

The short answer is FLUX.2-Klein. Both of its runs produced usable, correctly sized images. The two Qwen runs wrote valid PNG files, but every pixel was black. Z-Image Turbo completed quickly, but neither image met the scene brief: the frames were very soft, oversaturated, and wandered away from the cabin scene.

That is not a leaderboard. It is a record of this machine, these installed files, and this exact test.

What was tested

The test ran on an RTX 5090 Laptop GPU with 24,463 MiB reported VRAM, ComfyUI, a 1280 × 1792 portrait canvas, UniPC with the simple scheduler, and seeds 42 and 1337. Every run was submitted one at a time. The model cache was freed before switching models, so the GPU was never asked to hold all three models at once.

No LoRA, ControlNet, IP-Adapter, or reference image was used. The prompt set was supplied by Doubao. The setup, output validation, and review below were performed in the current Codex session; the visual scores are an assistant review, not a human preference study.

The original plan named three FP8 releases. Those exact files were not installed, so this is explicitly an installed-model comparison, not a substitute for that intended FP8 benchmark:

FLUX has a model-native guidance node. Keeping the sampler CFG at 1.0 there avoids applying guidance twice; the effective requested guidance is still 3.5. Qwen and Z-Image used CFG=3.5 in the sampler.

The shared negative prompt was:

3d, cg, blender, octane render, unreal engine, photorealistic, plastic texture, glossy skin, sharp modern digital illustration, ugly, deformed, disfigured, extra limbs, bad anatomy, oversaturated colors, neon, modern anime, ai artifacts, noise artifacts, watermark, text, signature

Prompts

The test deliberately used model-adapted prompts rather than forcing one tag list on all three architectures.

FLUX.2-Klein

Studio Ghibli animation scene, Hayao Miyazaki style, young girl standing on wooden terrace of mountain cabin at dusk, long hair blown by wind, distant layered mountain forest, thin evening mist, soft warm sunset diffused light, hand-painted cel shading, subtle watercolor texture, faint fine film grain, quiet nostalgic atmosphere, cinematic wide shot

Qwen Image

Studio Ghibli animation, hand-drawn Hayao Miyazaki style. At dusk, a young girl stands on the wooden terrace of a small mountain cabin, her long hair moving in the evening wind. Layered mountain forests recede in the distance, with light evening mist in the valley. Vintage cel-painted animation texture, subtle gouache grain, faint old-film grain, soft warm diffused dusk light, a quiet nostalgic mood, cinematic wide-angle framing, and restrained colors.

Z-Image Turbo

Studio Ghibli animation-film frame, hand-drawn Hayao Miyazaki style. At dusk, a young girl stands on the terrace of a mountain cabin, her long hair lifted by the wind. Distant layered forests, thin evening mountain mist, soft warm sunset light, cel-painted coloring, a light gouache texture, faint film grain, a quiet nostalgic mood, and cinematic composition.

The six outputs

FLUX.2-Klein, seed 42

This is the stronger FLUX frame. It has a readable cabin, terrace, girl, wind-blown hair, layered mountains and valley haze. The image leans more toward a contemporary anime illustration than a literal vintage film frame, but the watercolor-like paper texture and controlled dusk palette carry the intended mood.

FLUX.2-Klein, seed 1337

This second frame changes the angle and wardrobe but still satisfies the scene. The light is warm, the proportions are stable, and the mountain depth reads immediately. It is a useful confirmation that the first result was not a one-seed accident.

Qwen Image, seed 42 and 1337

Both files decode as RGB 1280 × 1792 PNGs, but each contains exactly one RGB value: (0, 0, 0). That is a completed file operation, not an image result. The Qwen VAE and text encoder were loaded according to the ComfyUI log, and older local Qwen base smoke outputs show the same all-black failure at other resolutions and settings. I therefore marked the installed Q6 setup as invalid on this host, rather than pretending a black frame is a low score.

Z-Image Turbo, seed 42

Z-Image Turbo, seed 1337

Z-Image did return non-black pixels, and it did put a long-haired figure in a green landscape. That is not enough. Both runs are visibly soft, strongly green/cyan, and include implausible bubble or lamp-like forms. The cabin terrace is not a stable subject. For this particular brief, they fail the “clean, restrained hand-painted dusk” bar.

Scores and runtime

Scores are 1–5. — means no image exists to judge. The Qwen black frames are invalid rather than “1/5 art.”

The first run for a model includes loading and warm-up, so wall time should not be read as a clean throughput benchmark. The useful operational observation is simpler: all successful model loads stayed under the 24,463 MiB card limit, but Z seed 1337 came closest at 23,633 MiB.

I2I: preserving an illustrated two-character scene

The I2I source is the user-supplied third attachment: a two-character illustration. I resized it without stretching from 960 × 1280 to 1280 × 1707, then added 42 px of neutral padding at the top and 43 px at the bottom to meet the fixed 1280 × 1792 canvas. The original file was not modified. The other four attachments were not submitted to any model; using them as extra identity references would turn this into a different, multi-reference test.

All I2I runs retained UniPC, the shared negative prompt, paired VAE, seeds 42 and 1337, and denoise=0.65. They were run one model at a time. The prompts were supplied by Doubao; output verification and the 1–5 review below are from the current Codex session.

I2I-A: style preservation

The intent was to preserve the original composition, poses, and framing while strengthening the hand-painted cel / watercolor / film-grain treatment.

FLUX keeps the broad two-person layout and gestures in both seeds, but it redraws faces, garments, and shoes. That is adequate composition preservation, not identity locking. Z keeps the rough layout yet visibly damages faces, limbs, and clothing. Qwen’s two files again decode as 1280 × 1792 RGB PNGs containing only (0, 0, 0).

I2I-B: rain-night edit

The edit prompt asked for rain, wet surfaces, and a soft night glow while keeping the original composition and poses unchanged.

At this fixed denoise=0.65, FLUX adds readable rain streaks while retaining the figures, but it does not turn the bright scene into a convincing night scene or make the floor substantially wet. That makes the edit a partial pass, not a success. Z neither makes a credible rain-night scene nor preserves clean structure.

I2I prompts

FLUX.2-Klein

I2I-A: Hayao Miyazaki Studio Ghibli, hand-painted cel animation, subtle watercolor texture, faint film grain, preserve original composition, preserve character pose, preserve camera framing

I2I-B: Hayao Miyazaki Studio Ghibli, hand-painted cel animation, rainy night, heavy rain, wet surface, night soft ambient glow, preserve original composition, preserve character pose, preserve camera framing

Qwen Image

I2I-A: Studio Ghibli and Hayao Miyazaki-inspired hand-painted animation, cel-painted coloring, a slight gouache texture, faint old-animation film grain; strictly preserve the source composition, character poses, camera angle, and object layout.

I2I-B: Studio Ghibli and Hayao Miyazaki-inspired hand-painted animation. Change the scene to a rainy night with heavy rain, wet reflective surfaces, and soft night ambient light; strictly preserve the source composition, character poses, camera angle, and object layout.

Z-Image Turbo

I2I-A: Studio Ghibli and Hayao Miyazaki-inspired hand-painted animation, cel-painted visual style, a light gouache texture, faint film grain; keep the source composition, character poses, and camera angle unchanged.

I2I-B: Studio Ghibli and Hayao Miyazaki-inspired hand-painted animation, rainy night, heavy rain, wet reflective objects, and soft night glow; keep the source composition, character poses, and camera angle unchanged.

What I would use next

For this machine and this animation-style T2I task, I would use the installed FLUX.2-Klein Q8 workflow as the working baseline. It is the only one here that produced two complete, presentable frames without added conditioning.

I would not continue tuning the installed Qwen Q6 base blindly. The black-frame behavior repeats outside this run, and a new Qwen test needs a verified working model/runtime combination before it is worth spending more GPU time. I would also not pick the current Z-Image Turbo BF16 workflow for this brief unless its prompt path or model pairing is revisited; its failure is visual, not just a missing file.

For this source at the requested fixed settings, I would use FLUX.2-Klein for style-preserving redraws. I would not present it as a reliable rain-night editor at denoise=0.65; the result needs a stronger editing path or a separately approved parameter sweep. Qwen remains blocked by the repeatable black-frame fault, and Z needs a corrected model/runtime pairing before another I2I trial.