# Aspect Ratio Decision Guide — Universal > **HARD RULE — every image prompt MUST explicitly declare an aspect ratio at the end.** Never leave aspect to model default. The aspect is chosen ONCE at project intake (showrunner Addım 1B) and inherited by every downstream skill — director, storyboard-builder, image-prompt-engineer, video-prompt-engineer. Per-cell aspect drift is forbidden. This guide is **project-agnostic**. It gives the decision criteria; each project picks its aspect ratio during showrunner intake and locks it in `WORKFLOW.md` → `Aspect:` field. Every prompt then inherits that aspect — no per-cell guessing, no model defaults. --- ## Why this rule exists Real production incident (2026-05-21): A documentary project's first 6+ cell prompts were written at **21:9 cinemascope** by default. The actual delivery target was **YouTube + community-event projector**, which is **16:9 native**. All 6 prompts had to be rewritten or post-letterboxed. Root cause: skill defaulted to "cinematic = 21:9" without checking the delivery target. **Lesson:** Default to **16:9**, not 21:9. Cinemascope (21:9) is **cinema-only** — theatrical release, festival, prestige HDR streaming. Everything else (YouTube, TV, web, projector, social) is 16:9 native and renders 21:9 as letterboxed bars. --- ## Decision table — delivery target → aspect ratio | Delivery target | Aspect ratio | Why this aspect | |---|---|---| | **YouTube standard video** | **16:9 widescreen** | Native player aspect. 21:9 gets letterboxed (black bars top + bottom). | | **TV broadcast** (any region) | **16:9 widescreen** | Industry standard since ~2009. | | **Web embed / corporate / event projector** | **16:9 widescreen** | All standard projectors and web players are 16:9 native. | | **Documentary delivered to community event / streaming** | **16:9 widescreen** | Plays correctly on every device without letterbox. | | **Reel / TikTok / IG Story / YouTube Shorts / vertical mobile** | **9:16 vertical** | Mobile-first social, vertical viewport. | | **IG feed post (square)** | **1:1 square** | IG feed native; older convention but still common. | | **IG portrait feed post** | **4:5 portrait** | Modern IG feed default; takes more vertical real estate than 1:1. | | **Theatrical cinema release** | **21:9 cinemascope** (2.39:1) | True cinema aspect; designed for theatre screens. | | **Film festival submission** | **21:9 cinemascope** (or 1.85:1 flat) | Festival projection standards. | | **Prestige streaming HDR cinema** (e.g. Netflix premium cinematic) | **21:9 cinemascope** | Cinema-grade delivery. | | **Magazine / print spread / editorial card** | **varies — ASK USER** | Project-specific; depends on layout. | | **Character anchor / 6-view turnaround reference sheet** | **1:1 square** | Multi-panel grid is an internal asset, independent of project aspect (see `character-designer` SKILL.md HARD RULE). | | **Character outfit variant / single-figure reference** | **inherit project aspect** | Reference is for downstream cells, so it adopts project aspect. | --- ## MOST PROJECTS = 16:9 **Default to 16:9 unless the project explicitly states one of:** - Theatrical cinema release → 21:9 - Film festival submission → 21:9 (or 1.85:1) - Prestige HDR streaming cinema → 21:9 - Mobile vertical (reel/short/story) → 9:16 - IG square feed → 1:1 If unsure → ask the user **before** writing any prompt. Never assume "cinematic look = 21:9". --- ## Per-aspect composition implications Choosing the aspect ratio changes how every shot is framed. Same scene, different aspect = different headroom, different subject sizing, different background reveal. ### 16:9 widescreen (1.78:1) — THE DEFAULT **Frame proportions:** moderate horizontal, balanced vertical. - **Wide establishing:** subject 35-50% frame width. Sky/ceiling AND ground visible. Comfortable vertical context. - **Portrait / face shots:** head and shoulders fit naturally. Small headroom at top. Eye-line on upper third. - **OTS (over-the-shoulder):** shoulder/back of head occupies meaningful vertical space. Subject sits centered-to-third. - **Macro / detail (page, hand, object):** subject centered; horizontal trim minimal. - **Lateral pan in post:** still works — crop window slides L→R inside the 16:9 frame; pan range is shorter than 21:9 but smooth. - **Best for:** documentary, YouTube, TV, web, projector, corporate, multi-platform. ### 21:9 cinemascope (2.39:1) — CINEMA ONLY **Frame proportions:** strongly horizontal, narrow vertical. - **Wide establishing:** subject 25-40% frame width. Sky and ground COMPRESSED — vertical context minimal. Landscape rules. - **Portrait / face shots:** face occupies less vertical space; needs more horizontal context around it (off-center placement common). Headroom often dropped. - **OTS:** shoulder takes more horizontal real estate; subject pushed further from center. - **Macro / detail:** strong horizontal subject (book spine, weapon, line of objects) reads well; tall narrow subjects feel cramped. - **Lateral pan in post:** native — designed for it. Sweeping vista moves. - **Best for:** theatrical, festival, prestige drama, large-format cinema. ### 9:16 vertical (0.5625:1) — MOBILE SOCIAL **Frame proportions:** strongly vertical, narrow horizontal. - **Wide establishing:** subject 50-70% frame width (subject dominates because horizontal context is squeezed). Vertical space lets you stack foreground + mid + background up the frame. - **Portrait / face shots:** face fills most of frame; close framing is the default. Headroom often increased to leave space for text overlays at top. - **OTS:** rare — vertical aspect doesn't suit OTS. Prefer direct close-up or POV. - **Macro / detail:** vertical subjects (face, body, tall objects) read well; horizontal subjects feel cropped at edges. - **Lateral pan in post:** awkward — vertical frame doesn't support horizontal motion. Vertical pan / tilt works better. - **Best for:** Reels, TikTok, YouTube Shorts, IG Story, mobile-first social. ### 1:1 square (1:1) — IG FEED + REF SHEETS **Frame proportions:** equal both axes. - **Wide establishing:** subject 40-50% frame width. Symmetrical compositions work best. - **Portrait / face shots:** head + shoulders fit; eye-line center or upper third. - **OTS:** works but feels static; both subjects roughly equal weight. - **Multi-panel grid (6-view reference sheet):** ideal — 2x3 or 3x2 panel layouts fit naturally in 1:1. - **Best for:** IG feed posts, character reference sheets, symmetrical compositions. ### 4:5 portrait (0.8:1) — IG PORTRAIT FEED **Frame proportions:** slightly vertical, near-square. - **Wide establishing:** similar to 1:1 but with extra vertical breathing room. - **Portrait / face shots:** excellent for single-figure portraits — face capture is generous, body extends down into frame. - **Macro:** vertical objects read well. - **Best for:** IG portrait feed posts, magazine portrait editorial. --- ## How to declare aspect ratio in a prompt Every image prompt ends with an explicit aspect declaration. Model-specific syntax: | Model | Syntax | |---|---| | **Midjourney v7** | `--ar 16:9` (parameter) | | **Flux Pro / SD 3.5** | `aspect_ratio: "16:9"` (API param) + sentence in prompt: "Aspect ratio: 16:9 widescreen." | | **Nano Banana 2 / Nano Banana Pro** | Sentence in prompt: "Aspect ratio: 16:9 widescreen." | | **GPT-Image-2** | `size: "1792x1024"` (API param — closest preset to declared aspect) + sentence in prompt: "Aspect ratio: 16:9 widescreen." | | **Imagen 4** | `aspectRatio: "16:9"` (API param) + sentence in prompt | | **Ideogram v3** | `aspect_ratio: "16:9"` (API param) + sentence in prompt | | **Recraft v3** | `size: "1820x1024"` (closest preset) + sentence in prompt | **Universal rule:** ALWAYS declare aspect in BOTH the API parameter AND a final sentence in the prompt text. Some models ignore one or the other; declaring both is the only reliable way. **Sentence template (paste verbatim at end of prompt):** ``` Aspect ratio: <16:9 widescreen / 21:9 cinemascope / 9:16 vertical / 1:1 square / 4:5 portrait>. ``` --- ## Decision workflow (apply BEFORE writing any prompt) ``` Step 1: Read WORKFLOW.md → Aspect: field ↓ Step 1a: Is the aspect field present? - YES → use it. Done. - NO → STOP. Ask user: "What's the delivery target? (YouTube → 16:9 / Cinema → 21:9 / Reel → 9:16 / IG square → 1:1 / Other → tell me)" ↓ Step 2: Write prompt with the declared aspect. - End the prompt with: "Aspect ratio: ." - Set the API parameter to match. ↓ Step 3: Verify after writing — does the aspect declaration appear in the final prompt? If missing → add it before delivering. ``` --- ## Common errors to avoid ### Error 1 — "Cinematic = 21:9" assumption "Cinematic" is a **visual style** (anamorphic look, controlled lighting, film stock), NOT an aspect ratio. A 16:9 documentary can absolutely be "cinematic." Do not equate cinema look with cinema aspect. ### Error 2 — Defaulting to model preset GPT-Image-2 defaults to 1024x1024 (1:1). Midjourney defaults to 1:1. If you don't declare aspect, you get the model's preset — often wrong for the project. ### Error 3 — Per-cell aspect drift Every cell in a project MUST use the same aspect. If Cell 1 is 16:9 and Cell 2 is 21:9, they cannot be cut together. Aspect is a project-level decision, not a per-cell decision. ### Error 4 — Forgetting the API parameter Declaring aspect in the prompt text alone is unreliable — some models ignore prompt aspect and use the API parameter only. Always set BOTH. ### Error 5 — Choosing aspect to match the location "This is a wide landscape, so 21:9." NO. Aspect is chosen by delivery target, not by scene content. A wide landscape in a YouTube documentary is still 16:9 — just frame the landscape to read inside 16:9. ### Error 6 — Mid-project aspect change Once aspect is locked in `WORKFLOW.md`, all already-generated assets (character refs, location refs, cells) are tied to it. Changing aspect mid-project means re-generating everything or post-cropping (with loss). Lock the aspect at intake, not later. --- ## Cross-references - **Showrunner intake:** `showrunner/SKILL.md` → Addım 1B captures aspect ratio as the second project-level question. - **Image prompt writing:** `image-prompt-engineer/SKILL.md` → "Davranış qaydaları" → Aspect ratio HARD RULE. - **Storyboard cell inheritance:** `storyboard-builder/SKILL.md` → every cell prompt inherits project aspect, no per-cell override. - **Director shot composition:** `director/SKILL.md` → framing decisions adapt to declared aspect. - **Image validation:** `image-validator/knowledge/prompt-consistency-checks.md` → F-16 checks aspect ratio match against project standard. - **Character reference sheet exception:** `character-designer/SKILL.md` → 6-view turnaround stays 1:1 regardless of project aspect. --- *Version: 1.0 | Created: 2026-05-21 | Trigger: real production incident — project defaulted to 21:9 when delivery was 16:9 YouTube/event.*