{"course":{"slug":"ai-images","title":"Image Generation, in Practice","url":"https://addaly.com/learn/ai-images","level":"beginner","track":"create"},"lesson":{"slug":"what-the-image-is-for","title":"Start at the placement, not the picture","url":"https://addaly.com/learn/ai-images/what-the-image-is-for","position":12,"of":69,"minutes":8,"answer":"The final placement fixes the dimensions, the crop, the amount of detail that will ever be visible and the file format, and every one of those decisions is cheaper to make before generating than after.","keyIdea":"The final placement fixes the dimensions, the crop, the amount of detail that will ever be visible and the file format, and every one of those decisions is cheaper to make before generating than after."},"body":{"format":"markdown","text":"## \"Something for the launch\"\n\nThat is the brief you will actually receive. It contains no dimensions, no placement, no ratio and no idea of whether the thing will be seen at 400 pixels wide on a phone or at two metres on a wall. Generating against it wastes an afternoon, because the first question at review will be \"can we get it in a square for Instagram too\", and the answer will be no.\n\nThe fix is one question asked first: **where does this appear?** Everything else follows from the answer.\n\n## The numbers you will actually meet\n\nKeep these somewhere. They change slowly and they decide your generation size.\n\n- **Instagram feed portrait**: 1080 × 1350 (4:5). The single most common social deliverable.\n- **Instagram/TikTok story or reel cover**: 1080 × 1920 (9:16).\n- **Open Graph card** for a link preview on most platforms: 1200 × 630 (roughly 1.91:1). Cropped hard on both sides on some surfaces.\n- **YouTube thumbnail**: 1280 × 720 (16:9), and it will be displayed as small as 246 × 138.\n- **Website hero**: commonly 2560 wide for a desktop banner, with the height decided by the section, and a separate mobile crop.\n- **A4 page at 300 dpi**: 2480 × 3508. A5 is 1748 × 2480.\n- **A3 poster at 300 dpi**: 3508 × 4961.\n- **Roll-up banner, 850 × 2000 mm**: at 150 dpi that is 5020 × 11811, which no generator produces directly and which you reach by upscaling a correctly proportioned render.\n\nTwo of these deserve a note. The YouTube thumbnail is a 1280-pixel image that most people see at a fifth of that size, so detail below a certain scale is wasted effort and contrast is everything. And large-format print does not need 300 dpi: a roll-up banner viewed from two metres is perfectly sharp at 100 to 150 dpi, and a billboard at 30 metres is fine at 15. People generate uselessly enormous files because they learned one number and applied it everywhere.\n\n## What the placement tells you beyond size\n\n**How long it is looked at.** A story frame gets under two seconds. A poster on a wall gets thirty. That difference decides how many elements the composition can carry, and it is a stronger constraint than any style choice.\n\n**Where the type goes.** If a headline will sit across the top third, that third needs to be quiet (a plain sky, a wall, a gradient) and you should generate it that way rather than blurring it afterwards. Asking for \"negative space in the upper third for a headline\" in the prompt works surprisingly well and costs nothing.\n\n**What the format has to be.** A photographic hero delivers as JPEG or WebP. A product cut-out for a shop listing needs a transparent PNG, which no diffusion model outputs directly: it comes from generating on a plain background and cutting it out afterwards. Discovering this at delivery is an unpleasant hour.\n\n**Whether it must tile or repeat.** A background pattern has a constraint no amount of prompting fixes casually, and it needs a seamless-tiling workflow chosen at the start.\n\n## Ask these four questions\n\nBefore generating anything, you want four answers in writing. They take one message to obtain:\n\n1. What are the final pixel dimensions, and are there other sizes it must also work in?\n2. Will type sit over it, and where?\n3. Print or screen? If print, what process and what size?\n4. Does anything real have to be in it: a specific product, a named person, a building?\n\nThat fourth question is the one that saves the most time, and the next lessons in this block are largely about what to do when the answer is yes.\n\n## The limit worth stating plainly\n\nA single generated image cannot serve every placement. A 1080 × 1350 portrait crops badly to 1200 × 630, and stretching it is visible. The professional answer is to generate wider than you need and crop down, which the next lesson covers, or to generate each placement separately from a shared reference.\n\nWhat you should not do is promise one image will cover six placements before checking the ratios. It is the commonest small failure in this work, it is discovered at the worst possible moment, and it is avoided by thirty seconds of arithmetic at the start."},"check":{"question":"A client asks for a launch image for \"socials and the website\". What is the most useful first action?","options":[{"text":"Ask for the exact placements and their pixel sizes, since ratio, detail and type placement all follow from them.","correct":true},{"text":"Generate a square image, because a square is the format that crops acceptably to the widest range of social and web placements without visible distortion.","correct":false,"tempting":"A square is a compromise that satisfies nothing well; it crops badly to both 9:16 and 1.91:1, and the hedge is chosen instead of the information that would remove the need for one."},{"text":"Generate at the highest resolution the model supports so that every placement can be produced by downscaling from a single large master file later.","correct":false,"tempting":"Resolution is not the constraint; aspect ratio and crop-safe composition are, and no amount of extra pixels makes a 4:5 frame work as a 1.91:1 card."},{"text":"Begin with the visual concept and settle the technical dimensions once the client has approved a direction they are happy with.","correct":false,"tempting":"Sounds like sensible creative sequencing, but approving a composition before knowing its frame means the approved thing may be impossible to deliver in the required shape."}]},"prev":{"slug":"cost-and-batching","title":"You are paying to make decisions you could make cheaply","url":"https://addaly.com/learn/ai-images/cost-and-batching"},"next":{"slug":"aspect-ratio-and-the-native-bucket","title":"The ratios the model was trained on, and what happens outside them","url":"https://addaly.com/learn/ai-images/aspect-ratio-and-the-native-bucket"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"cite":"Addaly (2026) 'Start at the placement, not the picture', in Image Generation, in Practice. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/ai-images/what-the-image-is-for (Accessed: 13 October 2026).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"Start at the placement, not the picture","courseTitle":"Image Generation, in Practice","module":{"index":2,"slug":"the-brief","title":"From a request to a specification you can generate against"},"answer":null,"keyIdea":"The final placement fixes the dimensions, the crop, the amount of detail that will ever be visible and the file format, and every one of those decisions is cheaper to make before generating than after.","hero":{"kind":"plate","image":null,"alt":null,"caption":null},"blocks":[{"t":"h2","id":"something-for-the-launch","runs":[{"text":"“Something for the launch”"}]},{"t":"p","runs":[{"text":"That is the brief you will actually receive. It contains no dimensions, no placement, no ratio and no idea of whether the thing will be seen at 400 pixels wide on a phone or at two metres on a wall. Generating against it wastes an afternoon, because the first question at review will be “can we get it in a square for Instagram too”, and the answer will be no."}]},{"t":"p","runs":[{"text":"The fix is one question asked first: "},{"text":"where does this appear?","b":true},{"text":" Everything else follows from the answer."}]},{"t":"h2","id":"the-numbers-you-will-actually-meet","runs":[{"text":"The numbers you will actually meet"}]},{"t":"p","runs":[{"text":"Keep these somewhere. They change slowly and they decide your generation size."}]},{"t":"ul","items":[[{"text":"Instagram feed portrait","b":true},{"text":": 1080 × 1350 (4:5). The single most common social deliverable."}],[{"text":"Instagram/TikTok story or reel cover","b":true},{"text":": 1080 × 1920 (9:16)."}],[{"text":"Open Graph card","b":true},{"text":" for a link preview on most platforms: 1200 × 630 (roughly 1.91:1). Cropped hard on both sides on some surfaces."}],[{"text":"YouTube thumbnail","b":true},{"text":": 1280 × 720 (16:9), and it will be displayed as small as 246 × 138."}],[{"text":"Website hero","b":true},{"text":": commonly 2560 wide for a desktop banner, with the height decided by the section, and a separate mobile crop."}],[{"text":"A4 page at 300 dpi","b":true},{"text":": 2480 × 3508. A5 is 1748 × 2480."}],[{"text":"A3 poster at 300 dpi","b":true},{"text":": 3508 × 4961."}],[{"text":"Roll-up banner, 850 × 2000 mm","b":true},{"text":": at 150 dpi that is 5020 × 11811, which no generator produces directly and which you reach by upscaling a correctly proportioned render."}]]},{"t":"p","runs":[{"text":"Two of these deserve a note. The YouTube thumbnail is a 1280-pixel image that most people see at a fifth of that size, so detail below a certain scale is wasted effort and contrast is everything. And large-format print does not need 300 dpi: a roll-up banner viewed from two metres is perfectly sharp at 100 to 150 dpi, and a billboard at 30 metres is fine at 15. People generate uselessly enormous files because they learned one number and applied it everywhere."}]},{"t":"h2","id":"what-the-placement-tells-you-beyond-size","runs":[{"text":"What the placement tells you beyond size"}]},{"t":"p","runs":[{"text":"How long it is looked at.","b":true},{"text":" A story frame gets under two seconds. A poster on a wall gets thirty. That difference decides how many elements the composition can carry, and it is a stronger constraint than any style choice."}]},{"t":"p","runs":[{"text":"Where the type goes.","b":true},{"text":" If a headline will sit across the top third, that third needs to be quiet (a plain sky, a wall, a gradient) and you should generate it that way rather than blurring it afterwards. Asking for “negative space in the upper third for a headline” in the prompt works surprisingly well and costs nothing."}]},{"t":"p","runs":[{"text":"What the format has to be.","b":true},{"text":" A photographic hero delivers as JPEG or WebP. A product cut-out for a shop listing needs a transparent PNG, which no diffusion model outputs directly: it comes from generating on a plain background and cutting it out afterwards. Discovering this at delivery is an unpleasant hour."}]},{"t":"p","runs":[{"text":"Whether it must tile or repeat.","b":true},{"text":" A background pattern has a constraint no amount of prompting fixes casually, and it needs a seamless-tiling workflow chosen at the start."}]},{"t":"h2","id":"ask-these-four-questions","runs":[{"text":"Ask these four questions"}]},{"t":"p","runs":[{"text":"Before generating anything, you want four answers in writing. They take one message to obtain:"}]},{"t":"ol","start":1,"items":[[{"text":"What are the final pixel dimensions, and are there other sizes it must also work in?"}],[{"text":"Will type sit over it, and where?"}],[{"text":"Print or screen? If print, what process and what size?"}],[{"text":"Does anything real have to be in it: a specific product, a named person, a building?"}]]},{"t":"p","runs":[{"text":"That fourth question is the one that saves the most time, and the next lessons in this block are largely about what to do when the answer is yes."}]},{"t":"h2","id":"the-limit-worth-stating-plainly","runs":[{"text":"The limit worth stating plainly"}],"role":"limit"},{"t":"p","runs":[{"text":"A single generated image cannot serve every placement. A 1080 × 1350 portrait crops badly to 1200 × 630, and stretching it is visible. The professional answer is to generate wider than you need and crop down, which the next lesson covers, or to generate each placement separately from a shared reference."}]},{"t":"p","runs":[{"text":"What you should not do is promise one image will cover six placements before checking the ratios. It is the commonest small failure in this work, it is discovered at the worst possible moment, and it is avoided by thirty seconds of arithmetic at the start."}]}],"check":{"question":[{"text":"A client asks for a launch image for “socials and the website”. 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