Participating Frequently

Question

AI Denoise creates rectangular artifacts in smooth skies

Forum|Forum|27 days ago
July 19, 2026
17 replies
196 views

AI Denoise creates rectangular artifacts in smooth sky areas.

The artifacts are not limited to the Lightroom preview. They are permanently written into the generated DNG and remain visible in Photoshop and exported JPEG files.

The artifacts become much easier to see after increasing the Dehaze slider, but they are already present in the DNG.

I reproduced the issue with:

- Canon EOS R6 Mark II (CR3)
- Canon EOS R5 Mark II (CR3)
- iPhone 17 Pro Max (DNG)

The issue occurs in both Lightroom Classic and Lightroom Desktop.

Disabling GPU acceleration does not change the result.

System
Lightroom Classic 15.4.1
Camera Raw 18.4

Lightroom Desktop 9.4.1

macOS Tahoe 26.5.2

MacBook Pro 16"
Apple M4 Pro
48 GB RAM

Steps to reproduce
1. Open a RAW/DNG with a smooth blue sky.
2. Run AI Denoise with default settings.
3. Open the generated DNG.
4. Increase Dehaze to reveal the artifact more clearly.
5. Export as JPEG.
6. Open the DNG or JPEG in Photoshop.

The rectangular artifacts remain visible.

JohanElzenga

Community Expert

I’m a bit puzzled about your step 3 “Open the generated DNG”. Lightroom Classic 15 does not generate a denoised DNG anymore, it is now a non-destructive edit. This was changed in Lightroom Classic 14.4 if I remember correctly.

-- Johan W. Elzenga

D

drtonyb

Legend

@JohanElzenga

You can ignore Step 3. The issue has nothing to do with Denoise anyway. It’s Dehaze (used inappropriately) and White Balance. Read my analysis posted earlier below.

P

pjcamera

Participant

I have exactly the same problem (camera = Canon R5ii) so it’s not an isolated event (and hopefully not user error).

F

feinschdensAuthor

Participating Frequently

The problem occurres also with raws from r6 ii and the iPhone 17 pro. I would hope for a user error. Easier to fix ;)

do you have a raw to test?

F

feinschdensAuthor

Participating Frequently

Unfortunately, I couldn’t upload the RAW files directly, so I’ve provided them via WeTransfer:

https://we.tl/t-40UArdng3LwyBfTb

The download link is valid for 3 days.

Please let me know if you need any additional files or information.

johnrellis

Legend

You can attach files here, including raw files, up to 47 MB.

F

feinschdensAuthor

Participating Frequently

Thank you for the information.

31_08_25-78.CR3

D

drtonyb

Legend

@feinschdens

LrC 15.4.1/LrD 9.4.1 no longer generate an AI Denoised DNG, so this step

3. Open the generated DNG.

makes no sense.

If willing, provide your example raw file for others to test.

F

feinschdensAuthor

Participating Frequently

Thanks for your reply.

I think there was a misunderstanding. My report is not about a generated DNG.

The issue is simply this:

I open a RAW file.
I run AI Denoise.
After increasing the Dehaze slider, rectangular block artifacts become visible in smooth sky areas.
The artifacts are also present in Photoshop and in the exported JPEG, so they are not just a Lightroom preview issue.

I attached two JPEGs to the report: one without AI Denoise and one with AI Denoise. The block artifacts are visible in the denoised version.

I can also upload the original RAW file if that helps reproduce the issue.

F

feinschdensAuthor

Participating Frequently

I hope this helps

31_08_25-78.CR3

kglad

Community Expert

@feinschdens

wrong forum. use use https://www.adobe.com/products/wishform.html

F

feinschdensAuthor

Participating Frequently

Thanks for your reply.

Sorry, could you clarify what you mean by "wrong forum"?

I thought this was the Lightroom Classic bug reporting forum. Are you suggesting that this issue should be reported through the Adobe Wishform instead? If so, could you explain why?

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