Image Format Selection Checklist
Complete this checklist before comparing file sizes. A compact output that loses a required property is not an optimization.
Requirements
- Where must the file open?
- Is it a master, editing intermediate, archive, or delivery copy?
- Is the content photographic, flat graphic, screenshot, scan, icon, or vector?
- Must alpha, animation, pages, layers, or paths survive?
- Are color profiles, bit depth, or metadata required?
- What dimensions and maximum bytes are allowed?
- Does untrusted content require a restrictive security policy?
Candidate scorecard
| Criterion | Required? | Candidate passes? | Evidence |
|---|---|---|---|
| Receiver support | Yes | Test import/display | |
| Required structure | Format and implementation | ||
| Visual quality | Representative sample | ||
| Byte budget | Measured output | ||
| Future editability | Master retained |
Decision rule
Eliminate candidates that fail a mandatory property. Test the remaining formats with the hardest representative asset. If the current format passes every requirement, keep it. Otherwise use the decision tree and then verify the exact route.
Final QA
- Open in the destination.
- Check dimensions and orientation.
- Inspect detail and gradients.
- Test transparency on contrasting surfaces.
- Confirm frames/pages.
- Measure actual bytes.
- Retain the source.
Team handoff
Store the completed scorecard with the asset role. Record the master location, approved outputs, encoder policy, required backgrounds, dimensions, owners, and review date. Re-evaluate when the destination changes rather than applying an old decision to a new channel.
Apply the checklist to common assets
Photograph for a website
Compatibility, acceptable visual loss, rendered dimensions, and delivery bytes usually matter more than alpha. Keep the camera or editing master, then compare supported photo-oriented outputs at the final display size. Do not declare a winner from one image because portraits, foliage, grain, and gradients stress encoders differently.
Interface screenshot
Small text, flat colors, and sharp edges make artifacts easy to see. Test PNG and suitable modern alternatives at 100% zoom. If the screenshot documents a bug or legal record, preservation requirements may outweigh delivery size.
Logo or icon
Retain the vector master when one exists. For raster delivery, specify background behavior, edge quality, exact dimensions, and platform requirements before choosing PNG, WebP, AVIF, or ICO. A smaller opaque file is not equivalent to a transparent asset.
Scan or archival image
Separate the preservation master from access copies. Check bit depth, pages, metadata, and color requirements before any conversion. A convenient web derivative should not silently replace the record copy.
Acceptance test
Test the most difficult representative file in every real destination. Record whether it opens, renders with correct orientation and color, preserves required structure, and stays within dimension and byte limits. Approve a format only after the receiving workflow passes; standards support alone is not enough.
Common mistakes
- Scoring file size before mandatory features.
- Using a delivery copy as the new master.
- Ignoring animation, pages, or vector paths.
- Assuming every implementation supports every standard feature.
- Choosing one format for photographs, screenshots, and icons.