Am interested to upgrade with GPTImage2. But I still can't find the answer.
So far only found
A) Resolution 1k
1024x1024, 1280x720, 720x1280 (all in 96 dpi, 24 bits)
What is B) Quality Tiers?

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Google AI Overview:
GPT Image 2 — Limits & Cost
Cost scales with pixel count and quality tier. Larger sizes and higher quality use more output tokens.
A) Resolution
- 1K (e.g. 1024×1024): Fast default. Best for thumbnails, drafts, quick variations.
- 2K (e.g. 2048×2048): Standard pro output. Ideal for most social and web graphics.
- 4K (e.g. 3840×2160): Max for print or high-detail work. Slower; may show slight artifacts.
B) Quality Tiers
- Low: Fastest and cheapest. Good for exploration and drafts.
- Medium: Production standard. Strong detail and texture.
- High: Max detail for hero images, faces, fabrics, and complex backgrounds.