asc-screenshot-resize

asc screenshot resize

Use this skill to prepare screenshots for App Store Connect. Do not rely on a hard-coded dimension table in this skill; the CLI owns the current size matrix.

Source of truth

Always discover current accepted sizes from asc first:

asc screenshots sizes --output table
asc screenshots sizes --all --output table

For local validation before upload:

asc screenshots

Common current device-type anchors:

• IPHONE_65 for the common 6.5-inch iPhone screenshot set.
• IPAD_PRO_3GEN_129 for the common 12.9/13-inch iPad screenshot set.

Run asc screenshots sizes --all when targeting other display types such as 6.9-inch iPhone, Apple TV, Mac, Vision Pro, iMessage, or Watch.

Workflow

1. Sanitize filenames

macOS screenshots can contain hidden Unicode spaces that make tools fail with "not a valid file". Sanitize before batch work:

2. Inspect dimensions and metadata

App Store Connect rejects screenshots with alpha transparency. Strip alpha by round-tripping through JPEG:

Batch-strip alpha from PNGs:

3. Resize only after choosing a target from asc

Pick a width and height from asc screenshots sizes --all. sips -z takes height first, then width:

Batch resize to a chosen target:

4. Validate outputs with asc

5. Upload only after validation

Guardrails

• Treat asc screenshots sizes --all as authoritative; Apple size requirements change.
• Do not stretch screenshots across incompatible aspect ratios unless the user accepts the visual tradeoff.
• Always output to a separate file or directory to preserve originals.
• Screenshots must be PNG or JPEG and must not include alpha transparency.
• Convert Display P3 or other color spaces to sRGB when needed:

• Prefer asc screenshots validate over visual inspection before upload.