Feature Request: Add optional image format conversion for HTML export compatibility

Lettera Lettera feedback
1

Hi,

I noticed a browser compatibility issue when exporting Markdown documents containing HEIC images to HTML.

What happens

HEIC images display correctly inside Lettera.

When exporting the document to HTML with images embedded as Base64 data, the exported HTML also displays correctly in Safari. However, the HEIC images do not render when the same HTML file is opened in Chrome.

For example, the exported HTML may contain an embedded image like:

data:image/heic;base64,...

Safari can display it, while Chrome cannot.

This seems to be a browser compatibility issue

I understand that this is most likely related to Chrome’s lack of HEIC/HEIF support rather than a problem with Lettera’s Base64 encoding or HTML export itself.

So I don’t think preserving the original HEIC image is necessarily incorrect.

However, from a user’s perspective, this may still be unexpected. If an image displays correctly inside Lettera and the document is exported as a standalone HTML file, I would generally expect the exported result to remain visually consistent when opened in common browsers.

This becomes especially relevant when the HTML file is intended to be shared with other people, since the recipient may not be using Safari.

Feature request

Would it be possible to provide an optional image compatibility setting when exporting to HTML?

For example:

  • Preserve original image format — current behavior

  • Convert HEIC/HEIF images to WebP

  • Optionally support JPEG or PNG as alternative formats

  • Optionally provide an image quality/compression setting

WebP could be a particularly useful option because it has broad browser support while still providing relatively good compression, which is important when images are embedded directly into HTML as Base64 data.

Another possible approach would be a general “browser-compatible images” option, where Lettera automatically converts image formats that may not be supported by common browsers.

Steps to reproduce

  1. Add a HEIC image to a Markdown document.

  2. Confirm that the image displays correctly in Lettera.

  3. Export the document as HTML with images embedded as Base64.

  4. Open the exported HTML file in Safari — the HEIC image displays correctly.

  5. Open the same HTML file in Chrome — the HEIC image does not render.

I think an optional conversion setting would make HTML exports more portable while still allowing users who prefer the original image format to keep the current behavior.

Thanks!