imagen-4-fast Portrait Prompt Reference: Realistic and Artistic Dual Styles

A prompt reference entry for developers, demonstrating two portrait styles on imagen-4.0-fast using the same subject: a realistic route pursuing believable texture, and an artistic route leaning toward painterly and stylized rendering. It only uses the text inputs declared by the author's route: prompt, aspect_ratio, an optional negative_prompt, and seed. This piece uses a 3:4 vertical format, suited to portrait composition; negative_prompt is used to suppress common realistic defects (over-smoothed skin, plastic-looking skin, distorted hands), and seed makes it easy to reproduce the same result. The realistic prompt focuses on concrete, verifiable photographic elements: lens focal length, light source direction and hardness, skin tone and skin texture descriptions, and low-interference treatment of the background. The artistic prompt, in turn, focuses on formal language: brushwork or stylized rendering, a restricted color palette, and treatment of contours and highlights. Use cases: serving as a comparison baseline when writing portrait prompts for image generation APIs; comparing how the realistic and stylized orientations respond to the same subject when tuning parameters; and also serving as an example of internal team prompt standards. The model has improved at generating text within images, but this entry focuses on portraits and does not involve text layout. Note that this model only supports text input and cannot take images as reference input.