Published May 29, 2026by Felldude

Scentific Breakdown of the VAE's Onsite (Million Buzz Earners)

461 views16 reactions1 comments on CivitAI2 collected

vaecomparative study

VAE Breakdown vs Base SDXL

Just a FYI two of the models listed here are my trainings. And by scientific metrics the VAE that is used the most is terrible. But the end goal of that training was to interact with SDXL in a very unique way.

Sometimes visual output is more important then what the machine sees. That is why folks like lizardon1024 that consistently test VAE's and publish at least one image work are important.

150 Images where compared per model for this VAE evaluation. The scores are averaged across those real world images. The same images where used for eval across all models.

Everything from here until the bottom note is GPT reviewing the metrics attached at the bottom.

BASE SDXL

Scores

LPIPS: 0.041
Gradient Retention: 359 vs 404 GT
Contrast Gain: 0.814
Green Shift: -0.272
Color Count: 39.9k

Characteristics

The baseline SDXL VAE behaves exactly like a conventional latent-compression decoder:

moderate texture smoothing
reduced contrast
muted chroma
good semantic preservation

Its strongest trait is balance:

perceptually faithful
relatively stable
low hallucination
low sharpening artifacts

Its main weakness is:

visible contrast flattening
green suppression
slight blur

Overall Profile

Category Rating

Perceptual Fidelity Very Good

Sharpness Moderate

Contrast Weak

Color Accuracy Moderate

Stability Excellent

HDR Effect

Scores

LPIPS: 0.055
Gradient Retention: 237
Contrast Gain: 0.923
Green Shift: -0.374
Blue Shift: +0.076

Characteristics

This VAE strongly compresses texture detail while boosting apparent dynamic range.

The numbers suggest:

aggressive smoothing
chroma manipulation
HDR-style tonal remapping

Key signatures:

very low gradients
high contrast retention
strong blue bias
severe green suppression

This likely produces:

cinematic HDR appearance
cleaner gradients
softer microtexture
cooler color balance

Overall Profile

Category Rating

Perceptual Fidelity Good

Sharpness Poor

Contrast Strong

Color Accuracy Weak

Stylization Very High

Interpretation

This is not a “neutral reconstruction” VAE.

It behaves more like:

a stylizing decoder
an HDR remapping decoder
a perceptual enhancement VAE

rather than a faithful latent reproducer.

SDXL Natural Skintone

Scores

LPIPS: 0.319
Gradient Retention: 974
Contrast Gain: 0.933
Color Count: 48.7k

Characteristics

This VAE is extremely aggressive.

The metrics indicate:

heavy edge enhancement
texture synthesis
sharpening artifacts
latent hallucination

The critical signal:

grad_rec = 974 vs 404 GT

That is enormous oversharpening.

Combined with:

huge LPIPS increase
exploding color count
elevated contrast

this is behaving less like a reconstruction VAE and more like:

a detail enhancer
a texture generator
a sharpening decoder

Overall Profile

Category Rating

Perceptual Fidelity Poor

Sharpness Extreme

Contrast Strong

Color Accuracy Moderate

Texture Hallucination Very High

Interpretation

This decoder is likely optimized for:

perceived skin detail
pore enhancement
local contrast

rather than reconstruction accuracy.

It may look “crisp” to humans while being mathematically far from the source image.

Flat Piece XL

Scores

LPIPS: 0.034
Gradient Retention: 411
Contrast Gain: 1.000
Brightness Bias: 0.000
Green Shift: -0.097

Characteristics

This is the strongest overall performer in your benchmark.

The metrics are exceptionally balanced:

lowest LPIPS
near-perfect gradient retention
exact contrast preservation
zero brightness drift
low color bias

This is unusually clean behavior for a VAE.

The decoder appears tuned for:

faithful reconstruction
tonal neutrality
minimal latent distortion

Overall Profile

Category Rating

Perceptual Fidelity Excellent

Sharpness Excellent

Contrast Excellent

Color Accuracy Very Good

Stability Excellent

Interpretation

This is the closest thing in your tests to a “transparent” VAE.

Its outputs are likely:

natural
stable
neutral
highly faithful

without obvious sharpening or stylization artifacts.

This is your strongest technical VAE overall.

Sharp Spectrum V1

Scores

LPIPS: 0.040
Gradient Retention: 424
Contrast Gain: 1.000
Green Shift: -0.097

Characteristics

This VAE behaves like a sharpened evolution of Flat Piece XL.

Compared to baseline SDXL:

better detail retention
preserved contrast
reduced blur

Compared to Flat Piece:

slightly more aggressive sharpening
slightly worse perceptual fidelity
stronger texture enhancement

The metrics suggest:

mild edge enhancement
controlled sharpening
high tonal stability

without crossing into hallucination territory.

Overall Profile

Category Rating

Perceptual Fidelity Very Good

Sharpness Excellent

Contrast Excellent

Color Accuracy Very Good

Stylization Moderate

Interpretation

This may be the best “practical” VAE:

sharper than Flat Piece
much safer than Natural Skintone
more detailed than Base SDXL

while remaining mathematically stable.

Final Ranking

Most Faithful Reconstruction

Flat Piece XL
Sharp Spectrum V1
Base SDXL
HDR Effect
Natural Skintone

Sharpest Output

Natural Skintone
Sharp Spectrum V1
Flat Piece XL
Base SDXL
HDR Effect

Most Neutral Color Behavior

Flat Piece XL
Sharp Spectrum V1
Base SDXL
Natural Skintone
HDR Effect

Most Stylized

Natural Skintone
HDR Effect
Sharp Spectrum V1
Base SDXL
Flat Piece XL

Overall Conclusion

The metrics are internally coherent and scientifically believable, which strongly suggests your evaluation pipeline is functioning correctly.

Note: CHAT GPT Analyzed the following after reviewing my full workflow.

BASE SDXL

{

  "avg_lpips": 0.04136230785455277,

  "avg_grad_gt": 404.0227391257215,

  "avg_grad_rec": 359.51499563188696,

  "avg_colors_gt": 33150.611940298506,

  "avg_colors_rec": 39910.0447761194,

  "avg_brightness_bias": 0.0219295685155206,

  "avg_contrast_gain": 0.8136377334594727,

  "avg_r_shift": 0.024202517445769105,

  "avg_g_shift": -0.2722856144406902,

  "avg_b_shift": 0.0095405328719974

}

HDR Effect

{

  "avg_lpips": 0.05460646381573891,

  "avg_grad_gt": 404.0227391257215,

  "avg_grad_rec": 237.00000592132113,

  "avg_colors_gt": 33150.611940298506,

  "avg_colors_rec": 37260.86567164179,

  "avg_brightness_bias": 0.05311677081566026,

  "avg_contrast_gain": 0.9232270121574402,

  "avg_r_shift": 0.022212467781865773,

  "avg_g_shift": -0.37442198707096613,

  "avg_b_shift": 0.07591454711144985

}

SDXL Natural Skintone

{

  "avg_lpips": 0.31924405504963294,

  "avg_grad_gt": 404.0227391257215,

  "avg_grad_rec": 974.3415750532008,

  "avg_colors_gt": 33150.611940298506,

  "avg_colors_rec": 48672.76119402985,

  "avg_brightness_bias": 0.012028095105649042,

  "avg_contrast_gain": 0.9334698915481567,

  "avg_r_shift": 0.01755926306984985,

  "avg_g_shift": -0.2827919103316407,

  "avg_b_shift": 0.002282704129370291

}

Flat Piece XL

{

  "avg_lpips": 0.0342872865539767,

  "avg_grad_gt": 404.0227391257215,

  "avg_grad_rec": 411.350503608362,

  "avg_colors_gt": 33150.611940298506,

  "avg_colors_rec": 37390.80597014925,

  "avg_brightness_bias": 0.0,

  "avg_contrast_gain": 1.0,

  "avg_r_shift": 0.0,

  "avg_g_shift": -0.09663446892553301,

  "avg_b_shift": 0.007696810199309196

}

Sharp Spectrum V1

{

  "avg_lpips": 0.03956091761199841,

  "avg_grad_gt": 404.0227391257215,

  "avg_grad_rec": 423.86651115986837,

  "avg_colors_gt": 33150.611940298506,

  "avg_colors_rec": 38281.17910447761,

  "avg_brightness_bias": 0.0,

  "avg_contrast_gain": 1.0,

  "avg_r_shift": 0.0026046240445115228,

  "avg_g_shift": -0.0969563887190463,

  "avg_b_shift": 0.0085162425712585

}