Feature Image Generation

Generate a Google Play feature graphic (1024×500 banner) from a JSON spec (or a text description via OpenAI) using fal.ai for image generation. Optionally include the app logo and screenshots that fal.ai places inside device frames.

generate-feature-image

kappmaker generate-feature-image \
    --prompt "A cute AI mascot generator for kids" \
    --app-name "Masclet" \
    --subtitle "Generate mascots, emotions, and expressions" \
    --primary-color "#E63946"

Or from a pre-authored spec (no OpenAI key needed):

kappmaker spec-template feature-graphic --output Assets/playstore/feature-graphic-spec.json
# fill the skeleton, then:
kappmaker generate-feature-image --spec Assets/playstore/feature-graphic-spec.json \
    --logo ./Assets/logo.png --reference ./screenshots/home.png

With logo + screenshots:

kappmaker generate-feature-image \
    --prompt "AI fitness coach with daily workouts" \
    --app-name "FitTrack" \
    --subtitle "Your daily workout partner" \
    --primary-color "#FF3B30" \
    --logo ./Assets/logo.png \
    --reference ./screenshots/home.png ./screenshots/profile.png

Flow

1. A detailed banner spec (JSON) is obtained — from your --spec file, or refined by OpenAI (GPT-4.1) from the inputs (app name, subtitle, primary color, concept, reference image positions). --print-prompt prints the spec-authoring instructions and exits, so you (or an AI agent) can write the spec without any API call. --logo/--reference still apply with --spec — they control the uploaded images.
2. fal.ai generates one wide image (nano-banana-2, or nano-banana-2/edit with reference images) at 16:9.
3. sharp resizes/crops to EXACTLY 1024×500 px (Google Play feature graphic spec) via center cover.

Output

Default path follows the Fastlane Supply convention so the existing publish flow picks it up automatically:

MobileApp/distribution/android/playstore_metadata/<locale>/images/featureGraphic.png

Falls back to Assets/playstore/featureGraphic.png outside a KAppMaker project. Override with --output <path>.

Options

Flag	Description	Default
--spec <path>	Pre-authored banner spec JSON — skips OpenAI entirely	—
--print-prompt	Print the spec-authoring instructions and exit (no API calls)	—
--prompt <text>	App concept / description (required unless --spec is given)	—
--app-name <name>	App name rendered on the banner (required unless --spec is given)	—
--primary-color <hex>	Brand color in hex, e.g. #FF3B30 (required unless --spec is given)	—
--subtitle <text>	Tagline rendered below the app name	—
--logo <path>	App logo PNG; rendered pixel-faithfully on the brand panel	—
--reference <paths...>	Screenshot paths to place inside device frames (max 10)	—
--output <path>	Custom output file path	Fastlane Supply path
--resolution <res>	AI resolution (1K, 2K, 4K)	2K
--locale <code>	Play Store locale for the default output path	en-US

Requirements

Requires falApiKey (prompted and saved on first use). openaiApiKey is only needed for the --prompt-without---spec flow. imgbbApiKey is recommended when passing --logo or --reference — it speeds up uploads. Without it, the CLI falls back to inline base64 data URIs.

Tips

• The logo (image #1) is rendered exactly as-is — the model is instructed not to redraw or recolor it. Pass a clean transparent-background PNG for best results.
• Reference screenshots are placed inside modern phone device frames at a slight angle. Order matters: the first reference becomes the most prominent device on the banner.
• The primary color visibly dominates the brand panel background or accents.
• Only the app name and subtitle appear as text — no AI-generated lorem copy.