Creating a poster usually starts with a blank canvas. Then come the decisions: what to say, where to place it, which image to use, and how to make the whole thing feel consistent.
An AI poster generator can remove much of that setup. Instead of writing a long image prompt, you give Sharper's AI image generator a short design brief, choose a few visual settings, and receive a finished image you can download.
This walkthrough uses one simple example: a grand-opening poster for a fictional neighborhood coffee shop. You can reproduce it without uploading a logo, product photo, or brand guide.
The finished poster
Here is the result from the example in this guide:
The finished 4:5 marketing poster created from a two-line brief.
The poster has a clear reading order:
- Brand: Luma Coffee
- Event: Grand Opening
- Visual: A latte and pastry inside a warm neighborhood cafe
- Offer: Free pastry with every coffee on opening day
That is enough information for a useful promotional design without crowding the image.
How to create the poster in Sharper
1. Start a Design task
Open Sharper, select Design, and choose Marketing poster.
Choose Marketing poster to open a structured design brief instead of starting from a blank prompt.
Sharper also supports product images, graphic assets, and brand and packaging work. Marketing poster is the easiest place to begin because it can produce a complete result from only a subject and one visual idea.
2. Fill in the brief
Use these two fields:
- What are you promoting?
Luma Coffee grand opening - What should stand out?
A warm neighborhood cafe and a free pastry with every coffee on opening day
For Poster text, select Write it for me. Sharper will turn the brief into concise copy that fits the design.
The brief keeps content and design choices visible before generation begins.
You can also write the exact poster text yourself. That is useful when dates, prices, addresses, or approved campaign language must appear exactly as provided.
3. Choose the design settings
For this example, use:
- Ratio: 4:5
- Visual direction: Illustration
- Model: GPT Image 2.5 Flare
- Appearance: Auto
- Quality: Balanced
The 4:5 ratio works well for a portrait poster and social-media feed. Illustration gives the example a warm, crafted feel while keeping the offer easy to read.
Sharper also offers photography, line art, geometric, pixel-art, and text-only directions. You do not need to describe those styles inside the prompt; select the direction in the brief.
4. Generate and review
Select Done, check the summarized brief, and submit the task. Sharper prepares the visual direction, generates the image, checks the poster copy, and delivers the finished file in the task.
Before downloading, check three things:
- Is every required line present and spelled correctly?
- Can you understand the poster in a few seconds?
- Does the image support the offer instead of competing with it?
If something needs changing, continue in the same task with a direct instruction such as:
Make the offer larger and simplify the background, but keep the same warm illustrated style.
A reusable prompt for your own poster
You do not need to copy the coffee-shop concept. Replace the bracketed text below:
Create a marketing poster for [product, event, or topic]. Highlight [the main selling point or visual idea].
Good briefs are short and specific. Name one subject and one thing that should stand out. Add exact copy only when the wording matters.
For example:
- A weekend farmers market; highlight local produce and live music.
- A new running club; highlight a friendly first 5K for beginners.
- A seasonal skincare set; highlight the three products and gift-ready packaging.
When to add reference images
This example uses no uploads, but reference images are helpful when the result must preserve something real:
- Upload a logo when it must appear in the design.
- Upload a subject image when the product or person must remain recognizable.
- Upload a style reference when you already have an approved visual direction.
You can assign each image a role, so Sharper knows whether it is the subject, a logo, or inspiration for the style.
Why use a structured design brief?
A single free-form prompt often mixes content, layout, style, file format, and model settings into one paragraph. That makes omissions easy.
Sharper separates those decisions. The brief keeps the subject, selling point, poster text, reference images, aspect ratio, visual direction, model, appearance, and quality visible before the task runs. You can change one choice without rewriting everything else.
The result is still generated work and should be reviewed before publication, especially when a design includes prices, dates, addresses, regulated claims, or brand assets. But you begin with a coherent artifact instead of an empty canvas.
If the campaign needs more than one poster, build the visual system first. The AI graphic generator guide shows how to create reusable patterns and accents, while the AI packaging design guide carries the same colors and motifs onto physical products. For an ecommerce campaign, you can also create coordinated listing and lifestyle shots with the AI product photography guide.
Ready to try it? Open Sharper, choose Design → Marketing poster, and create your first poster from the reusable brief above.
FAQ
Can Sharper write the poster text?
Yes. Select Write it for me and Sharper will draft concise copy from the subject and selling point. You can enter exact text instead when the wording must be fixed.
Can I upload a logo or product image?
Yes. Add PNG, JPEG, WebP, or SVG reference images and identify how each should be used, such as subject, style reference, or logo.
Which poster sizes are available?
The design brief includes an aspect-ratio control. This example uses 4:5 for a portrait poster. Choose the ratio that matches where the design will appear.
Can I change the result after it is generated?
Yes. Continue in the same task and describe the revision you want, such as changing the emphasis, simplifying the background, or adjusting the visual direction.