# PNG-to-ICO editorial source notes

Checked: `2026-08-12` (Asia/Calcutta)

These notes support the Windows icon and favicon distinctions in `draft.md`. They do not replace the measured LocalFlux evidence in `test-record.md`.

## Primary guidance

### Microsoft Learn: Construct your Windows app's icon

- URL: <https://learn.microsoft.com/en-us/windows/apps/design/iconography/app-icon-construction>
- Verified in current web results on `2026-08-12`.
- Used for: Windows chooses an exact icon size first and otherwise scales down the next larger asset; a practical minimum app-icon set includes 16 × 16, 24 × 24, 32 × 32, 48 × 48, and 256 × 256; packaged Windows apps use target-size and scale-specific PNG assets.
- Editorial constraint: the article does not imply that one 256-pixel ICO frame is a complete production app-icon family.

### Microsoft Learn: Icons (Win32 design basics)

- URL: <https://learn.microsoft.com/en-us/windows/win32/uxguide/vis-icons>
- Verified in current web results on `2026-08-12`.
- Used for: traditional application icons commonly include several exact sizes in one ICO and require deliberate small-size design.
- Editorial constraint: this older guidance is presented as Win32-specific context, not as the manifest contract for every modern Windows project.

### WHATWG HTML Standard: Link type `icon`

- URL: <https://html.spec.whatwg.org/multipage/links.html#rel-icon>
- Used for: a website favicon is supplied through an HTML icon relationship and may declare icon sizes; it is a separate deployment task from producing a Windows application ICO.
- Editorial constraint: the article does not prescribe one favicon format or claim universal browser behavior.

## Local editorial references

- `docs/research/localflux-next-blog-topics-2026-08.md` ranked PNG-to-ICO as the third route article and required exact frame inspection, square/non-square/photo inputs, Explorer evidence, transparency caveats, and a favicon distinction.
- `src/LocalFlux.Core/Data/routes.json` exposes `image.png-to-ico` through the ImageMagick runtime.
- `src/LocalFlux.Core/Services/ImageMagickArguments.cs` applies a default `256x256` ICO bound when no visual resize is requested.

## Claim boundaries

- No universal file-size saving, visual-quality, transparency, metadata-removal, or compatibility claim is made.
- The article explicitly identifies the tested outputs as one-frame ICO files.
- File Explorer screenshots demonstrate Windows rendering for these files; they do not prove application packaging or browser favicon behavior.
- Production icon-size guidance is attributed to Microsoft rather than inferred from the LocalFlux outputs.