Which Tool Is Better for AI Image Detection: Undetectable AI vs Sightengine

AI-generated images are getting harder to spot. The question is whether today's detectors are keeping up.

A Nano Banana output used to be easy to clock. Something always felt off either the textures too smooth, and the details just slightly wrong in ways you couldn't quite name. 

Those days are mostly gone. 

Most modern AI image generation models have gotten good enough that the mistakes are subtle and most detectors weren't built for subtle.

That's the real test here. We ran  Undetectable AI and Sightengine through six image tests to find out which one actually delivers.

What is Undetectable AI?

Undetectable AI  built its name and brand as an AI humanizer, that's still its core product. But over time, the platform expanded into a broader AI content suite, and image detection powered by Truthscan became part of the bigger picture.

It's worth being upfront here, image detection is not Undetectable AI's main strength. 

Their primary strength is text (detecting AI and then rewriting it). Their image detection work is more accessible and creator-facing, designed for someone who needs a quick authenticity check without a technical setup with paid plans starting at a discounted price (for now) of $5 for 10,000 words.

Best for:

• Writers, marketers, and content creators
• Quick one-off image authenticity checks
• Users already in the Undetectable AI ecosystem for text tools

What is Sightengine?

Sightengine  is a different kind of product entirely. Their "genai" detection model is purpose-built for this problem. 

It analyzes pixel-level data only, meaning it doesn't rely on metadata or watermarks that can easily be stripped. 

It's been trained on millions of real and synthetic images across major generators — Midjourney, GPT-4o, Stable Diffusion, Ideogram, Flux, Bing Image Creator, and more.

The platform cites an academic benchmark from the University of Rochester and University of Kansas where Sightengine ranks as a leader in AI-generated media detection. 

For platforms screening user-uploaded content at scale, it's built exactly for that.

Best for:

• Developers and engineering teams
• Platforms moderating user-generated content at volume
• Enterprise use cases requiring API integration and compliance support

The Test Setup

For this test, we ran six images through both detectors:

• 1 image generated by ChatGPT (DALL-E)
• 1 image generated by Gemini
• 1 image generated by Midjourney
• 1 image sourced from Facebook
• 2 images taken on a personal phone camera

The goal: see how each tool handles both ends of the spectrum — obvious AI renders and authentic real-world photography.

The Actual Head to Head

Test #1: ChatGPT

Undetectable AI: Correctly flagged the image as AI generated
AI Likelihood Score: 99%

Sightengine: Correctly flagged the image as AI generated
AI Likelihood Score: 99%

Test #2: Gemini (Nano Banana)

Undetectable AI: Correctly flagged the image as AI generated
AI Likelihood Score: 99%

Sightengine: Correctly flagged the image as AI generated
AI Likelihood Score: 99%

Test #3:  Midjourney

Undetectable AI: Correctly flagged the image as AI generated
AI Likelihood Score: 99%

Sightengine: Incorrectly tagged the generated image as Real
AI Likelihood Score: 1%

Test #4: Social Media

Undetectable AI: Correctly tagged the image as Real with Digital Alterations
AI Likelihood Score: 38%

Sightengine: Correctly tagged the image as Real with 20% Face Manipulation
AI Likelihood Score: 20%

Test #5: Camera Photo 

Undetectable AI: Correctly tagged the image as Real
AI Likelihood Score: 4%

Sightengine: Correctly tagged the image as Real
AI Likelihood Score: 1%

Test #6: Phone Camera Photo (Cropped)

Undetectable AI: Incorrectly tagged the cropped image as AI generated
AI Likelihood Score: 92%

Sightengine: Correctly tagged the image as Real
AI Likelihood Score: 0%

The Score Summary

Test	Image Source	Correct?	Undetectable	Sightengine
#1	ChatGPT (AI)	✓ Both	99%	99%
#2	Gemini Nano (AI)	✓ Both	99%	99%
#3	Midjourney (AI)	✗ Sightengine	99%	1%
#4	Social Media	✓ Both	38%	20%
#5	Phone Camera)	✓ Both	4%	1%
#6	Phone Camera Cropped	✗ Undetectable	92%	0%
Average			83.3%	83.3%

Final Thoughts

Comparing these two tools directly is a bit like comparing apples and oranges. Undetectable AI is a broad AI content suite. Sightengine is a more dedicated image detection platform. 

That said, the test results speak for themselves. Both finished at 83.3% accuracy, but Sightengine got there slightly ahead. 

It gave an accurate reading on the real photos, especially the cropped image, and then stumbled on the Midjourney render. 

Undetectable AI caught that same Midjourney image no problem, but stumbled on the  cropped phone photo.

Both honestly have the kind of false positive that's hard to overlook.

If you're already using the Undetectable AI ecosystem, the image detection is a handy bonus, and if you're not,  just the number of functionality alone gives you tremendous value. 

And that value is what separates the two giving Undetectable the edge.