Image Resize — Platform-Aware Image Resizer

Resize and crop any image to exact dimensions for 60+ platform presets using ImageMagick's high-quality Lanczos resampling.

Prerequisites

ImageMagick is required. If not installed:

brew install imagemagick    # macOS
sudo apt install imagemagick # Debian/Ubuntu

How to use

Run the bundled script:

bash <skill-path>/scripts/resize.sh <input-image> [OPTIONS]

Options

Flag	Description	Default
--platform NAME	Generate image for a specific platform preset	(required unless --all)
--all	Generate images for every preset	off
--category CAT	Generate all presets in a category (e.g. youtube, appstore)	—
--output DIR	Output directory	./resized/
--list	List all available platform presets and exit	—
--fit	Fit image inside target (letterbox with padding) instead of cover-crop	off (cover-crop)
--pad-color HEX	Padding color when using --fit (6-digit hex, no #)	FFFFFF
--quality N	Output quality 1-100	92

Platform presets

The script knows these categories. For the full list of preset names and exact pixel dimensions, read references/platforms.md.

Category	Presets
Web / SEO	og-image, blog-cover, notion-cover
Chrome Extension	chrome-screenshot, chrome-small-promo, chrome-marquee-promo
Ads	feed-ad, post-ad
Play Store	play-icon, play-feature, play-screenshot-5, play-screenshot-6
App Store	appstore-iphone-15-pro-max, appstore-iphone-14-plus, appstore-iphone-14-pro, appstore-iphone-14, appstore-ipad-pro, appstore-mac, appstore-watch-ultra, appstore-watch-series
YouTube	youtube-profile, youtube-cover, youtube-thumbnail
TikTok	tiktok-profile, tiktok-video, tiktok-image-ad, tiktok-square-ad
Pinterest	pinterest-profile, pinterest-board-cover, pinterest-square, pinterest-medium, pinterest-long
Substack	substack-featured, substack-logo, substack-email-banner, substack-social, substack-cover
Threads	threads-profile, threads-square, threads-carousel
Instagram	instagram-feed-square, instagram-feed-portrait, instagram-stories, instagram-reels
Twitter	twitter-one-image, twitter-two-images, twitter-cover-photo, twitter-og
Dribbble	dribbble-shot
Bluesky	bluesky-post, bluesky-cover, bluesky-cover-mobile
Product Hunt	producthunt-gallery, producthunt-thumbnail
LinkedIn	linkedin-feed, linkedin-cover-business, linkedin-cover-personal, linkedin-stories
Facebook	facebook-news-feed, facebook-stories, facebook-cover-photo, facebook-og

Examples

Single platform — OG image for a blog post:

bash <skill-path>/scripts/resize.sh hero.png --platform og-image

All YouTube sizes at once:

bash <skill-path>/scripts/resize.sh channel-art.png --category youtube --output ./youtube-assets/

Every platform preset from one source image:

bash <skill-path>/scripts/resize.sh brand-logo.png --all --output ./all-sizes/

Fit mode (letterbox instead of crop) with black padding:

bash <skill-path>/scripts/resize.sh screenshot.png --platform appstore-iphone-15-pro-max --fit --pad-color 000000

List available presets:

bash <skill-path>/scripts/resize.sh --list

How it works

The script uses a cover-crop strategy by default — the same approach image editors use for "fill" mode:

1. Scale the image so it fully covers the target rectangle (using ImageMagick's resize WxH^ with Lanczos filter)
2. Center-crop to the exact target dimensions (using -gravity center -extent WxH)

This means no distortion and no empty space — the image always fills the frame, cropping from the center if the aspect ratios differ.

With --fit, the strategy flips: the image is scaled to fit inside the target, then padded to exact dimensions with a solid color. This is useful for screenshots or images where you don't want anything cropped off.

When to pick which mode

• Banners, covers, thumbnails, OG images — default cover-crop is usually best. The subject should be centered in the source image for best results.
• App Store / Play Store screenshots — use --fit so UI elements at the edges aren't clipped.
• Icons and profile photos — cover-crop works well since these are typically square-ish crops of a centered subject.
• Pinterest long pins — if your source is landscape, --fit avoids aggressive cropping.

Supported input formats

ImageMagick handles PNG, JPEG, TIFF, GIF, BMP, WebP, HEIC, and many more. Output format matches the input (a .png stays .png, a .jpg stays .jpg).

Output naming

Files are saved as <platform-name>.<ext> in the output directory. For example:

• resized/og-image.png
• resized/youtube-thumbnail.jpg
• resized/appstore-iphone-15-pro-max.png