ChatGPT’s New Image Tool vs Gemini Nano Pro

ChatGPT recently came up with its new dedicated image tool, and I compared it directly with Google Gemini Banana Nano Pro using exactly the same prompts across a series of tests. I focused on color, speed, watermark behavior, text accuracy, repeatability, style, and incremental edits. The results surprised me in more than one place.

I used the pro version of Gemini with the nano banana pro model and matched prompts side by side. I will leave it up to you to decide which one looks more accurate in each case, but you will see consistent differences in tone, realism, and output behavior.

Category	ChatGPT image	Gemini Banana Nano Pro
Color tone	Slightly warm color tones	Greenish, cooler looking color, often more vibrant
Image generation speed	Approximately twice the time to generate	Generates more instantly
Watermark	No watermark	Always leaves its watermark
Realism in photo style	Often closer to photo realistic rendering	Can look more cartoonish or poster-like
Object replacement	Replaced deer with tiger while keeping environment consistent	Replaced animal cleanly and kept environment consistent
Orientation control	Handled horizontal and portrait changes flawlessly	Handled orientation changes as expected
Text rendering in posters	Accurate spelling and a more traditional or original poster look	Accurate spelling and added a thin line like you pulled a card
Infographic labels	Clear winner with correct spelling and crisp labels	Spelling mistakes occurred in labels
Incremental edits	Handled glowing window, smoke from chimney, adding a wooden house	Handled the same edits reliably
Repeatability	Minimal unintended changes when editing prompts	Comparable in environment consistency
Preference for direct use	Preferred due to clarity, colors, realism, and no watermark	Requires cropping or watermark removal before use

ChatGPT image vs Google Gemini Banana Nano Pro - detailed comparison

Photo realistic scene - tone and realism

On the same photo realistic scene prompt, there is a clear difference in the way both models interpret color. ChatGPT generally comes up with slightly warm color, while Gemini focuses more on greenish, colder looking color. The Gemini picture is a little more vibrant, less realistic compared to what I am seeing on the other side. I prefer the warmth and realism from ChatGPT in this scenario.

Speed and watermark behavior

ChatGPT generally takes approximately twice the time to generate an image when compared to Gemini. Gemini generates images more instantly. Gemini always leaves its watermark. In ChatGPT there is no watermark. If I really want to use a photo just out of the model, ChatGPT is the way to go, because with Gemini I either crop the watermark or remove it later.

Object replacement - deer to tiger

I asked both to replace the animal with a tiger. Gemini can easily do that, and ChatGPT also did a commendable job in replacing the deer with a tiger. The tiger one looked slightly more pale compared to the deer one, but apart from lighting and the animal, nothing got changed. That repeatability in ChatGPT is great to see.

Orientation control - horizontal and portrait

I asked both to change orientation. I asked ChatGPT to make it horizontal and asked Gemini to make it portrait. You can simply ask the AI to make necessary changes. ChatGPT implemented and did it flawlessly, and this is expected from Gemini as well.

Text on posters - “Journey Beyond the Stars”

I asked both to generate a movie poster that says Journey Beyond the Stars. Creating these posters with very accurate spelling is a milestone both have accomplished. The ChatGPT poster looks much more traditional or original compared to the Gemini result in this regard. Gemini added a thin line that looks like you pulled a card, which adds a bit of believability.

Futuristic explorer - keeping and adding a glowing orb

Prompt: a futuristic female explorer wearing a leather jacket and goggles, standing on a rocky Mars-like terrain. ChatGPT generated what I asked, but I also added a second point about an object I defined as a glowing orb, which led to two different results. Since ChatGPT did not follow both instructions together at first, I reiterated to show the explorer holding a glowing orb. Comparing both versions side by side, you can decide which looks more realistic and better. For me personally, I prefer the ChatGPT-generated images, but it could be different for you.

Infographics - water cycle with labels

Prompt: showcase the water cycle with crisp labels like evaporation, condensation, precipitation, collection, colorful icons and arrows on a clean white background. There is a difference in approach and design. I give full points to ChatGPT here. I am using the latest and greatest banana nano, and there are still mistakes where the spellings are not correct. The clear winner is ChatGPT. I did not anticipate that ChatGPT would destroy Gemini Banana Pro in this regard.

Surreal scene - melting clock over a city at sunset

Prompt: a surreal scene where a giant clock melts over a city skyline at sunset in dreamlike style, with vivid color. ChatGPT’s result is very close to photo realistic rendering. Gemini looks more cartoonish in comparison. Both did a great job producing images, but one image has slight warmth, which is ChatGPT. Gemini still needs to work on colors, which I see handled better in ChatGPT. It is possible the style was not defined, and it chose a poster look, but by default I put my money on ChatGPT here.

Incremental edits - cottage and floating island

Prompt sequence 1: a cozy cottage in a snowy forest at twilight. Then change the cottage to have a warm glowing window and smoke rising from the chimney. Both did exactly that and did a great job. If you ask me which is my favorite picture, I will go with ChatGPT.

Prompt sequence 2: a floating island in the sky with grass and a single tree. This is more of a fantasy illustration. Both look really good. In terms of realism, ChatGPT clearly beats Gemini with the kind of detail it comes up with. After generating both images, I asked to add a small wooden house on the island. Both added the house. The house from ChatGPT is slightly bigger than the house from Gemini. I do not know why this happened, but this is the case.

In the end, ChatGPT has made significant improvement in its image generation engine. It is watermark free, and it comes up with the color I really like, which is a slightly warm tone. You may prefer the right-hand images from Gemini, but that is up to you.

Features breakdown - ChatGPT image

ChatGPT image - key features

• Warm color tone that often reads more realistic to my eye
• No watermark on outputs
• Handles object replacement and incremental edits with minimal unintended changes
• Accurate spelling in posters and infographics
• Can be slower, approximately twice the time compared to Gemini
• Orientation changes handled cleanly

Gemini Banana Nano Pro - key features

• Very fast generation that feels instant
• Watermark is always present on outputs
• Cooler, greenish tone that can appear vibrant but less realistic
• Competent object replacement and incremental edits
• Poster text accurate and sometimes adds small design touches like a thin line
• Infographics had spelling mistakes in my test

Pros and Cons - ChatGPT image

ChatGPT image - pros

• Watermark free images ready for direct use
• Realistic warmth in color and tone
• Strong repeatability when making edits
• Excellent text accuracy in posters and infographics

ChatGPT image - cons

• Slower generation time compared to Gemini
• Occasionally small tonal shifts like a pale subject on replacement

Gemini Banana Nano Pro - pros

• Very fast at generating images
• Competent at subject replacement and iterative edits
• Adds stylistic touches some may like
• Vibrant output that pops

Gemini Banana Nano Pro - cons

• Watermark on every image
• Cooler, greenish tone can feel less realistic
• Spelling mistakes in infographic labels in my test
• Tendency toward a more cartoonish or poster look

Use cases - ChatGPT image

When I would choose ChatGPT image

• I need watermark free images that I can use directly
• I want warmer tones and photo realistic results
• I care about accurate text in posters and infographics
• I need consistent edits without altering the environment

When I would choose Gemini Banana Nano Pro

• I need images generated as fast as possible
• I am fine with removing or cropping out a watermark afterward
• I prefer a cooler, more vibrant look or a poster style
• I want quick iterations and small stylistic touches

Final Conclusion

Both were competent across fundamental tasks like subject replacement, orientation changes, and incremental edits. ChatGPT consistently gave me warmer, more realistic images, watermark free outputs, and better text accuracy in posters and infographics. Gemini was faster and sometimes added interesting stylistic touches, but the watermark and cooler tone held it back for my use.

If you prioritize realism, accurate text, and direct usability, go with ChatGPT image. If speed is your top priority and you are comfortable with post-processing the watermark, Gemini Banana Nano Pro will serve you well. I will move toward ChatGPT because of the clarity, colors, and realism I see in its images.