The Art of AI Image Generation Prompts: Get High-Quality Images Faster
Struggling to get the images you want from AI? This article explains prompt writing based on the "one idea per sentence" principle. Discover practical techniques, including WebP optimization, to efficiently generate high-quality images.
Many people struggle with AI image generation, finding that the results don't match their vision or the quality isn't what they expected. Simply listing words isn't enough for AI to accurately understand your intent. In fact, designing prompts that understand AI's characteristics is the key to efficiently obtaining high-quality images.
Conclusion: Optimize Image Generation with Purpose-Driven Prompt Strategies
When creating prompts for AI image generation, the most important factor is "clarifying your objective." Do you need a realistic portrait, or an abstract landscape? The type of prompt and descriptive strategy you choose will vary significantly depending on your goal. For example, if you need detailed information, a "decomposed element type" prompt is effective. If you want to quickly try multiple ideas, a "template-based type" is useful. The ultimate goal is to maximize prompt efficiency, extracting the greatest effect with the minimal description. This approach also leads to improvements in LCP (Largest Contentful Paint) when using generated images on websites. This is because lighter prompts, free of unnecessary information, tend to result in more optimized image data generated by the AI.
3 Criteria for Choosing AI Image Generation Prompts
There are many ways to write AI image generation prompts, but the following three criteria can help you choose effective ones.
- Specificity (What do you want to draw?): Can you specifically designate the main elements, subject, background, and composition of the image you want the AI to generate? For example, instead of just "cat," describe it specifically as "a tabby cat curled up and sleeping by a sunny window."
- Information Volume (How detailed should the instructions be?): To what extent should you instruct the AI on the image's style, color scheme, lighting, and texture? Too much information can confuse the AI, while too little can lead to unintended results. Example: "A landscape painting of a starry night in the style of Van Gogh."
- Efficiency (Ease of Trial and Error): How efficiently can the prompt description facilitate the trial-and-error process? This considers whether you can try various variations with a short description, or achieve a desired image in one go with a detailed description. Example: Try various images with simple keywords like "photo, woman, beautiful, smiling, outdoors, natural light."
By considering these criteria, you can select a prompt strategy that suits your objective and generate high-quality images more efficiently.
Prompt Method/Type Comparison Chart
| Prompt Method/Type | Characteristics | Benefits | Drawbacks | Recommended For | Prompt Example |
|---|---|---|---|---|---|
| Decomposed Element Type | Describes elements individually in detail | Easy to convey intent accurately, high-quality images | Complex description, time-consuming | Those pursuing a specific image | Subject: girl, Background: cherry blossom avenue, Style: anime, Color tone: pastel, Expression: smile |
| Template-Based Type | Follows a pre-defined structure for description | Easy to write, quick trial and error | Difficult for fine-tuning | Those who want to quickly try multiple patterns | [Style] [Subject] [Background] [Lighting] [Color] |
| Free-Form Input Type | Describes freely in natural language | Intuitive, wide range of expression | Intent may not be clear | Those who want to expand ideas, abstract expressions | A mysterious creature standing in a fantastical forest, moonlight streaming through |
| Keyword List Type | Lists words and phrases | Simplest description, fast | Risk of unintended interpretation | Those who want to convey a rough image | cat, sleeping, window, sunlight, cozy |
Recommended Prompt Strategies for Different Use Cases
Now, let's introduce prompt strategies tailored to specific use cases. Choose the optimal method according to your objective.
Case 1: Generating an Image for a Website's First View
A website's first view is a crucial element that determines a visitor's first impression. It's necessary to generate a visually appealing yet lightweight image, keeping LCP (Largest Contentful Paint) in mind. Here, the "decomposed element type," which clearly specifies the subject, background, color tone, and composition, is optimal. By eliminating unnecessary elements and conveying only essential information to the AI, you can generate images that match your intent while keeping file sizes small. For example, for a corporate website, prioritize elements that convey reliability and professionalism.
Prompt Example: Subject: business person, Background: modern office, Composition: full body shot, Color tone: blue and white contrast, Atmosphere: professional, Lighting: natural light, Style: realistic
Case 2: Creating Multiple Pattern Eye-Catching Images for Blog Articles
Eye-catching images for blog articles serve to instantly convey the article's content and encourage clicks. If you plan to use them for multiple articles and want to efficiently generate diverse variations with a consistent style, a combination of "template-based type" and "keyword list type" is effective. By creating a basic template and swapping keywords for each article, you can easily generate multiple eye-catching images. At this time, if you consider converting to WebP format, being mindful of simple compositions will facilitate later image optimization.
Prompt Example (Template): Illustration symbolizing [topic], [emotion], [color scheme], [background], Style: flat design
Usage Example: Illustration symbolizing productivity improvement, hope, green and white, desk work background, Style: flat design
Case 3: Quickly Creating Impactful Images for SNS Posts
On social media, images that quickly grab users' attention and pique their interest in the post content are required. For this purpose, the intuitive "free-form input type" or the "keyword list type" that simply conveys elements are suitable. To increase the number of trials, it's efficient to first generate multiple patterns with a prompt that conveys a rough idea, and then choose the most effective one. Giving strong instructions for color and composition can enhance visual impact.
Prompt Example: Silhouette of a dragon soaring in the night sky, vibrant aurora background, mysterious, fantastical, digital art
Key Checkpoints for Creating Successful Prompts
A common failure in prompt creation is that the AI doesn't accurately understand the intent. To avoid this, use the following checkpoints:
- Be mindful of the one-idea-per-sentence principle: Avoid stuffing multiple instructions into a single prompt. Instead, give one clear instruction per sentence. Aim for the AI to recognize "a boy playing with a dog" and "in a park" as separate elements. For example, instead of
A boy playing with a dog in a park, break down the instruction asA boy is playing with a dog. The scene is in a park.As a general guide, aim to complete one instruction within approximately "40 full-width characters" (or about 20-25 English words). - Utilize negative prompts: Clearly giving instructions like "not ~" can improve the quality of generated images. For example, specify elements to avoid concretely, such as
bad art, deformed, ugly. - Consider WebP compatibility of generated images: It's important to think about image optimization from the prompt creation stage. Especially when intending to use images on a website, consider simple compositions and color schemes that can be effectively lightened through WebP conversion. Overly complex backgrounds or too many objects can cause file sizes to inflate.
- Try multiple prompts: Don't give up if the first prompt doesn't yield the ideal image. Try generating multiple times, changing expressions or reordering elements. Prompt writing will become more refined after about 3-5 attempts.
Frequently Asked Questions
Q. How much information should I include in a prompt?
A. It depends on the complexity of the image you want to generate, but the basic principle is to clearly describe the minimum necessary information, keeping the "one idea per sentence" rule in mind. Start with the main elements, then add details as needed. Example: Start with "beautiful landscape painting," then add "beautiful landscape painting, sunset, mountains, lake, realistic."
Q. Should I write prompts in English or Japanese?
A. Many AI image generation models are optimized for English prompts. Even if you input in Japanese, it's often translated internally into English, so if you want more accurate results, English is recommended. However, some models have enhanced Japanese support, so check the characteristics of the tool you are using.
Q. I'm concerned that generated images might negatively affect LCP. What should I do?
A. By specifying simple compositions and fewer objects in the prompt, the file size will be smaller, reducing the impact on LCP. Additionally, it's essential to use image compression tools or WebP conversion services after generation for optimization. Keep image width to a maximum of around "1920px" and convert to WebP to reduce file size by an average of 70%.
Q. What should I do if I run out of prompt ideas?
A. It's effective to refer to prompt examples published by others or get inspiration by looking at galleries of AI image generation services. Practicing breaking down elements of specific photos or paintings and converting them into prompts is also useful.
Your First Step to Prompt Improvement Starts Today
Now that you understand the art of prompt design for efficiently generating high-quality AI images, you can put it into practice immediately. First, try the "decomposed element type" prompt for the image you most want to generate. Specifically, break down the desired image into five elements: "subject," "background," "style," "color tone," and "atmosphere," describing each within approximately "40 full-width characters" (or about 20-25 English words). Then, generate an image based on that prompt and evaluate the result. This first step will pave your way to becoming an AI image generation master.