A Superwhite alternative that goes beyond white
Superwhite popularised HDR logo glow and does the white case well. This tool covers the same ground and adds the parts it does not: any colour, one region, and the brightness ceiling for the colour you actually chose.
The comparison below is drawn from each product’s public material. Where we could not verify a capability, it says so rather than guessing — and the two rows where they are ahead are listed too.
Last verified 29 August 2026. Competitor features change; re-check before relying on any single row.
Free, with no account and no watermark. Your image is processed in your browser and never uploaded — read how HDR glow works.
This is a free online alternative to Superwhite and similar HDR glow tools. Where a single-purpose tool brightens white and stops, this one lets you target any colour or region, computes each colour's exact-luminance ceiling before it clips, and verifies the HDR signalling of every file it writes. It exports Rec.2100 PQ as JPEG with an ICC profile, PNG with a cICP chunk, or a tone-mapped SDR fallback, at LinkedIn's own dimensions where that matters. It is free, requires no account, adds no watermark, and processes images entirely in your browser rather than on a server.
Feature by feature
| Capability | This tool | Superwhite | Note |
|---|---|---|---|
| White HDR glow | Yes | Yes | Both tools do the core job this category exists for. |
| Any-colour selection | Yes | Not advertised | Superwhite’s public material is built around white and bright-region highlights. |
| Connected-region selection | Yes | Not advertised | Glow one object rather than every pixel sharing its colour. |
| Exact-colour brightness limit | Yes | Not advertised | Shown live for the selected colour, computed from the BT.2020 matrix. |
| Brand-safe colour mode | Yes | Not advertised | Preserve caps brightness rather than letting the hue drift. |
| Multiple glow colours at once | Yes | Not advertised | Each selection is solved against its own colour limit. |
| LinkedIn export | Yes | Yes | Both rely on a Rec.2100 PQ profile surviving LinkedIn’s JPEG path. |
| HDR PNG for self-hosting | Yes | Yes | cICP signalling, which does not survive a platform re-encode. |
| Output verification | Yes | Not advertised | Every export is read back and its signalling checked after encoding. |
| Runs in your browser | Yes | Yes | Neither tool needs your image on a server. |
| Batch processing | Not yet | Yes | A genuine gap on our side today. |
| Saved presets | Not yet | Yes | Another gap. Planned, not shipped. |
| Price | Free | Check their site | Every feature here is free, with no account, watermark or export limit. |
Where they are genuinely better today
Batch processing and saved presets. If you push dozens of assets through the same settings every week, that is a real workflow advantage and this tool does not have it yet. Worth knowing before you switch.
Where this one goes further
The category name is the tell. “Superwhite” describes white, and the tooling around it reflects that. The interesting problem is the other colours — a brand green or a saturated blue has a hard brightness ceiling that white simply does not, and hitting it without controlling the trade-off shifts the hue.
That is the work here: a colour-volume solver that computes the ceiling for your exact colour, and three modes that decide whether brightness or fidelity wins when the two conflict. Plus region selection, so one object can glow rather than every pixel that happens to share its colour.
What are the numbers?
Every figure below is either a published constant or a value this tool computes. None is an estimate, and each one is traceable to the standard beside it.
| Measurement | Value | Source |
|---|---|---|
| Diffuse white reference | 203 nits | ITU-R BT.2408 |
| PQ maximum | 10,000 nits | SMPTE ST 2084 |
| 8-bit PQ code for diffuse white | 148 | Computed |
| 8-bit PQ code for 1,600 nits | 205 | Computed |
| Rec.2020 white ceiling | 10,000 nits | Computed |
| Rec.2020 green ceiling | 6,780 nits | Computed |
| Rec.2020 red ceiling | 2,627 nits | Computed |
| Rec.2020 blue ceiling | 593 nits | Computed |
| Blue's share of Rec.2020 luminance | about 6% | Computed |
| LinkedIn logo size | 400 × 400 px | Measured |
| LinkedIn post and ad size | 1200 × 627 px | Measured |
| LinkedIn JPEG re-encode | quality 90, 4:4:4 | Measured |
| Price | Free, no account | This site |
Where do these figures come from?
This tool implements published standards rather than an in-house approximation of them. Each specification below defines part of what the exported files contain.
- ITU-R BT.2100
Defines the HDR system this tool encodes into — BT.2020 primaries with the PQ transfer function.
- ITU-R BT.2408
Sets diffuse white at 203 nits, which is the reference every brightness figure here is measured against.
- SMPTE ST 2084
The PQ transfer function itself: absolute luminance from 0 to 10,000 cd/m², independent of display.
- ITU-T H.273
The code points behind cICP 9 16 0 1 — colour primaries, transfer characteristics, matrix and range.
- W3C PNG Third Edition
Specifies the PNG cICP chunk, which is how an HDR PNG declares itself without an ICC profile.