WSI: APP14 marker in JPEG bitstream

[Mathieu Malaterre]

Hi everyone,

I'm looking for some insight from the Cornerstone.js community regarding JPEG decoding behavior in web viewers.

We are having a discussion about whether the Adobe APP14 marker is necessary inside encapsulated JPEG tiles. My position is that it's redundant because the color space can be deduced directly from the SOF0 marker and DICOM metadata, but I want to ensure that removing it won't break decoding or color interpretation in web-based client loaders.

Full details are tracked in this issue:

* https://github.com/imi-bigpicture/opentile/issues/93

Any feedback from the dev team or users familiar with the underlying codecs would be greatly appreciated!

[David Clunie]

I have found that the APP14 (APPE) marker is necessary, since without it, some decoders and viewers will fail, so please do not remove it.

For a more detailed response from me, see https://github.com/imi-bigpicture/opentile/issues/93#issuecomment-4798212167

On Thursday, June 25, 2026 at 4:01:51 AM UTC-4 mathieu....@gmail.com wrote:

We are having a discussion about whether the Adobe APP14 marker is necessary inside encapsulated JPEG tiles. My position is that it's redundant because the color space can be deduced directly from the SOF0 marker and DICOM metadata, but I want to ensure that removing it won't break decoding or color interpretation in web-based client loaders.

...
* https://github.com/imi-bigpicture/opentile/issues/93

[Mathieu Malaterre]

Thank you, David. I wasn't aware of this modern requirement for APP14. I appreciate the detailed clarification and the links you provided.