Color Profiles and sRGB for Slack Messages

Updated August 15, 2026 · 8 min read

Colours that look vivid on your camera can look dull after upload if profiles are mishandled. Shared images live in workspace storage and get re-downloaded by every viewer, so smaller is kinder to everyone.

Recommended settings for Slack messages

SettingStarting point
FormatJPEG (WebP where accepted)
Widthabout 1600 px on the long edge
Quality78
File size500 KB or less

These are practical defaults. If the platform or form you are using publishes its own limits, follow those instead.

Color Profiles and sRGB

Most screens and browsers assume sRGB. Photos in wider profiles may shift when the profile is dropped during upload.

Browser-based compression outputs standard sRGB pixels, which is what Slack messages expects. If colours change dramatically, export from your editor in sRGB before compressing.

Step by step with TheCompressJPEG

  1. Open the compress JPEG to 500 KB tool, or the main compressor for custom settings.
  2. Drop in your image. Nothing is uploaded; it is processed in your browser.
  3. Set the maximum width to 1600 and the target size to 500 KB.
  4. Press Compress, check the result and download it.
Ready to try it? Compress your JPEG to 500 KB now. It's free and private.

Quick tips

  • Write a size limit slightly below the stated maximum to leave a margin.
  • Process private images locally rather than uploading them to unknown servers.
  • Crop out distractions so pixels go to the subject.
  • Use WebP where it is supported and you control the page.

FAQ

Is WebP accepted for e-learning courses?

It depends on the platform. JPEG is the safest choice when you are not sure.

What size should an image be for e-learning courses?

A practical default is about 1600 pixels wide and 200 KB or less, unless the destination states its own limits.

Can I compress images for e-learning courses without uploading them?

Yes. TheCompressJPEG runs entirely in your browser, so your images never leave your device.

Wrapping up

For Slack messages, the reliable recipe is simple: resize to around 1600 pixels, compress at quality 78 or to a 500 KB target, and check the result before you upload. Keep the original so you can always start again.

Related guides