Could you confirm this bug please

[PutinHuilo]

Could you please confirm this bug and possibly upvote on adobe forum i've been facing this since 2023.


When using Merge to HDR and Merge to Panorama option Update embedded JPEG previw = Full Size is ignored ACR saves resulting DNG with embedeed JPEG preview only 256x256 pixels.

Even later when that Panorama / HDR image is opened back and changed in ACR preview updates only to max 256x256 pixels depsite option Update embedded JPEG previw = Full Size.

 

[thebestcpu]

Well, I tried a Merge to HDR and followed all the steps, including updating the preview sizes in the DNG, but the maximum preview dimensions were 256 pixels.

Yet the link you provided brought me to the Adobe Community page, which looked like it had no access.

So not sure what to do at this point

John Wheeler

 

[PutinHuilo]

This is correct link https://community.adobe.com/t5/came...only-256x256px-for-panorama-hdr/td-p/13769975

Hope if enough people upvote this maybe they going to fix it.

 

[thebestcpu]

I upvoted and also added my own post to the thread copied here for what its worth:

Confirmed still a problem with Photoshop 2025 and ACR 17.2


This bug has been around for a long time.


It would be great if Adobe at least acknowledged this as a bug, even if it is low on their priority list to fix.


In addition, providing an Adobe workaround would be very helpful instead of having to use a non-Adobe app to correct this problem.


I certainly hope that the length of time on the low-priority bug list would eventually bump the priority for a real fix.


Just a suggestion from a retired engineering manager which including managing software.


John Wheeler

 

[JeffK]

Maybe it's not a bug...maybe it's a feature...

 

[thebestcpu]

Maybe it's not a bug...maybe it's a feature...

There were some Photoshop bugs back in the day , when I was interfacing with an Adobe employee working with me on some PS bugs. On one of them, he used almost the exact same wording: "intended to be that way to protect the customer." Yet they fixed it in the next revision. Makes me wonder if some companies have their employees go through "gaslighting" training.

 

[PutinHuilo]

In addition, providing an Adobe workaround would be very helpful instead of having to use a non-Adobe app to correct this problem.

Is there a way to correct preview size with any non adobe app?

I mean ideally to correct once so next time when edits are made using ACR it update preview full size JPG preview, not 256x256 again.

 

[thebestcpu]

There are a variety of ways and I have not checked them all out. For batch operations, it indicates using DNG converter is most reliable. Here is the online summary:

To correct small JPEG preview sizes inside DNG files, you need to regenerate a larger embedded preview and write it back into the DNG. The problem usually occurs when software (such as Adobe Camera Raw HDR/Panorama merge) embeds only a 256×256-pixel preview even when “Full Size” is selected. Fixing it requires rebuilding the preview using one of the following methods.


Method 1: Lightroom Classic. Import or select the DNG files. In the Library module, choose “Previews” and then “Build 1:1 Previews.” This forces Lightroom to generate a full-resolution JPEG preview. If another application needs the larger preview stored inside the file, you can optionally re-export the image as DNG.


Method 2: Adobe DNG Converter. Convert the DNG to DNG again. In the preferences, enable “Embed Fast Load Data” and set “JPEG Preview: Full Size.” The converter rewrites the DNG and replaces the small preview with a larger one.


Method 3: ExifTool replacement. ExifTool cannot generate a new preview image, but it can replace the small one if you supply a full-size JPEG. First extract the existing preview using “exiftool -b -PreviewImage input.dng > preview.jpg” to confirm it is small. Then create a full-size JPEG from your processed version of the file and write it back using “exiftool -PreviewImage=fullsize.jpg input.dng”. To verify the result, read the dimensions using “exiftool -PreviewImageWidth -PreviewImageHeight input.dng.”


If a viewer continues to display the old small preview after the fix, it may be using a cached thumbnail. Closing and reopening the application or clearing its cache usually resolves that.

Hope that is helpful
John Wheeler