How to turn a low quality image into an amazing 4K photo using Gemini and NanoBanana.

My video about improving image quality went viral, and I am receiving hundreds of questions on how to do it. The truth? It is much simpler than you think. All you need is Gemini, one precise prompt, and NanoBanana to do the heavy lifting. The result: a sharp 4K image that looks like it was shot on a professional camera.

The quick guide: 4 steps to a 4K image

• Choose an image you want to upgrade (portrait, product photo, personal shot)
• Upload it to Gemini and select the Create Image option
• Enter the dedicated prompt (attached below, ready for copying)
• NanoBanana works its magic, and within seconds you have a sharp and impressive 4K image

The prompt is in English on purpose. Image generation models understand it much better in English, and the results are more consistent. Copy it as is, do not translate.

The complete prompt for image upgrading (to copy into Gemini)

Enhance the portrait while strictly preserving the subject's identity with accurate facial geometry. Do not change their expression or face shape. Only allow subtle feature cleanup without altering who they are. Keep the exact same background from the reference image. No replacements, no changes, no new objects, no layout shifts. The environment must look identical. The image must be recreated as if it was shot on a Sony A1, using an 85mm f1.4 lens, at f1.6, ISO 100, 1/200 shutter speed, cinematic shallow depth of field, perfect facial focus, and an editorial-neutral color profile. This Sony A1 + 85mm f1.4 setup is mandatory. The final image must clearly look like premium full-frame Sony A1 quality. Lighting must match the exact direction, angle, and mood of the reference photo. Upgrade the lighting into a cinematic, subject-focused style: soft directional light, warm highlights, cool shadows, deeper contrast, expanded dynamic range, micro-contrast boost, smooth gradations, and zero harsh shadows. Maintain neutral premium color tone, cinematic contrast curve, natural saturation, real skin texture (not plastic), and subtle film grain. No fake glow, no runway lighting, no oversmoothing. Render in 4K resolution, 10-bit color, cinematic editorial style, premium clarity, portrait crop, and keep the original environmental vibe untouched. Re-render the subject with improved realism, depth, texture, and lighting while keeping identity and background fully preserved. NEGATIVE INSTRUCTIONS: No new background. No background change. No overly dramatic lighting. No face morphing. No fake glow. No flat lighting. No over-smooth skin.

What the prompt actually does

If the first result is not perfect, do not give up. Run the exact same prompt one or two more times. Each run gives a different variant, and sometimes the third one is gold. Updating a single word in the prompt (for example indoor instead of studio) can change everything.

Tips for professional use of the prompt

• A source image with reasonable quality yields results 10 times better than a completely blurry image
• If it is not a portrait but a product or landscape, replace the words about facial geometry with a description of the object
• You can add specific changes you want at the end of the prompt (for example: brighter background, more contrast)
• The result preserves the person and the background, only upgrading the quality. It does not replace an image, it cleans it up

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Who this guide is most valuable for

Frequently asked questions about image upgrading with AI

NanoBanana is Google's image generation model available through Gemini. It specializes in upgrading and rewriting images with high fidelity to the source, making it the leading tool for quality improvement without changing the person or background.

Yes, image generation is also available in Gemini Free with a daily limit. In the Gemini Advanced version (paid), the limit is higher and you have access to more advanced models. For those who create many images, the investment pays off.

No, if you use this prompt. It specifically asks for real skin texture (not plastic) and emphasizes no oversmoothing and no fake glow. This is the difference between a professional upgrade and an artificial look. The negative instructions at the end of the prompt are the main reason it looks realistic.

Yes, according to Gemini's terms of use, generated images can also be used for commercial purposes. You should check the updated terms on the Google AI website as they are updated.

Yes. Replace the part about facial geometry with the product description (preserve product shape and details). The rest of the prompt (cinematic lighting, 4K resolution, no artificial glow) also works great on products, real estate, food, and any object.

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Frequently asked questions

What is NanoBanana?

NanoBanana is Google's image generation model available through Gemini. It specializes in upgrading and rewriting images with high fidelity to the source, making it the leading tool for quality improvement without changing the person or background.

Does this also work in the free version of Gemini?

Yes, image generation is also available in Gemini Free with a daily limit. In the Gemini Advanced version (paid), the limit is higher and you have access to more advanced models. For those who create many images, the investment pays off.

Will the image look like drawn AI art?

No, if you use this prompt. It specifically asks for real skin texture (not plastic) and emphasizes no oversmoothing and no fake glow. This is the difference between a professional upgrade and an artificial look. The negative instructions at the end of the prompt are the main reason it looks realistic.

Can this be used commercially?

Yes, according to Gemini's terms of use, generated images can also be used for commercial purposes. You should check the updated terms on the Google AI website as they are updated.

Can the same method be applied to product images?

Yes. Replace the part about facial geometry with the product description (preserve product shape and details). The rest of the prompt (cinematic lighting, 4K resolution, no artificial glow) also works great on products, real estate, food, and any object.

Where can you learn more tricks like this?

In the AI Master club you learn to build by yourself: no-code landing pages, automations, and AI agents even without a technical background. In addition, there is a weekly live session with Amichai Shekel on new tools and workflows, comprehensive lessons and guides on Claude, Cowork, and Claude Code, a prompts and skills library, and an active community of business owners. 47 NIS per month, subscription renews automatically. One-click cancellation anytime.