P: External Lens profiles can affect mosaic DNGs differently than linear/proxy DNGs.

[Guo_XM]

Title: Inconsistency in Lens Corrections for Different File Formats

The Lens Corrections results in Lightroom Classic/ACR are inconsistent across different file formats, particularly between raw files (eg.ARW) and HDR files (-HDR.dng), where Distortion Corrections and Vignetting Corrections differ, leading to imperfect alignment during further post-processing.

This issue is especially pronounced in photos taken with zoom lenses.

RAW files：

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HDR files：

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50%+50%：

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A typical example:
In the same cityscape night scene, I took a series of [bracketed exposure photos] for creating a [High Dynamic Range background] and a series of [time-lapse photos] for maximum value synthesis of [TAIL LIGHT TRAILS]. I merged the [bracketed exposure photos] to generate a -HDR.dng, made slight adjustments, and then synchronized the photo settings with the [time-lapse photos], exporting all as TIF files for manual post-synthesis.

However, when I overlapped the HDR photo with the time-lapse photo, I found that the lens corrections were not consistent, especially with noticeable deviations at the edges of the image, which prevented me from effectively using Photoshop's mask tool to delineate the areas I wanted to preserve.

This issue has been bothering me for a long time, causing my workflow to be frequently interrupted.

Is there another way to make Lightroom Classic apply the same Lens Corrections to photos of different formats?

[John R Ellis]

"I merged the [bracketed exposure photos] to generate a -HDR.dng ... However, when I overlapped the HDR photo with the time-lapse photo, I found that the lens corrections were not consistent, especially with noticeable deviations at the edges of the image"

This may be independent of lens corrections -- the brackets, the merged DNG, and the time-lapse photos may not align perfectly even with Lens Corrections disabled throughout the workflow. Two possible causes of misalignment:

- Even with a solid tripod mount, slight vibrations (including from mechanical shutters) could cause small differences in the positioning of the camera, such that the brackets and time-lapse photos don't perfectly align.

- When you select the Auto Align option of HDR Merge, LR will do a geometric transformation of the photos to align them. If the input photos are not aligned, then Merge might produce a DNG with a larger misalignment. In some quick testing, I've observed that Auto Align of a raw merged with its identical virtual copy produces a result that is unaligned with the original by a few pixels vertically and horizontally.

You can test each of those possible causes by disabling Lens Correction entirely and then comparing the brackets, the merged DNG, and the time-lapse photos for alignment. An easy way to compare is to select two or more images in Library and do Photo > Edit In > Open As Layers In Photoshop; then in PS you can zoom in and toggle the top layer off on and on in the Layers panel.

If you do these tests with Lens Correction entirely disabled and you don't observe differences in alignment, that would suggest that something else (such as raw versus DNG) is in play. To make further progress on understanding this (and to get Adobe's attention), we'd have to see a small set of original raws, along with the precise workflow steps.  You could upload the raws to Dropbox, Google Drive, or similar and post the sharing link here.

[Guo_XM]

感谢您的回复！

事实上，这个例子只是为了说明这个问题如何影响实际工作，因为有很多方法可以重现这个问题。

为了消除这些[真实世界条件]的干扰，实际上有一种特殊的方法可以只用一组原始文件来完成：

1. 右键菜单 - 创建虚拟副本
2. 折叠堆栈
3. 右键菜单 - 照片合并 - HDR...（Ctrl+H）
4. 取消选中[自动对齐]并输出HDR文件

在这种情况下，您可以生成与原始文件几乎相同的线性 HDR 文件，并且可以重现问题。

我的网络有点差，目前很难上传大文件，但在下面的示例库中，您可以轻松找到使用本主题中使用的 Sigma 24-70mm F2.8 DG DN（E 卡口）镜头拍摄的原始文件：

Sigma 24-70mm F2.8 DG DN（E 卡口）样品库 

[Guo_XM]

Thank you for your response!

In fact, this example is just to illustrate how this issue can affect actual work, as there are so many ways to reproduce this problem.

To eliminate the interference of these [real-world conditions], there is actually a special method that can be done with just one set of raw files:

1. Right-click menu - Create Virtual Copy
2. Collapse Stack
3. Right-click menu - Photo Merge - HDR... (Ctrl+H)
4. Uncheck [Auto Align] and output HDR files

In this case, you can generate a linear HDR file that is almost identical to the raw file, and the problem can be reproduced.

My internet is a bit poor, and it is currently difficult to upload large files, but in the following sample gallery, you can easily find the raw files taken with the Sigma 24-70mm F2.8 DG DN (E-mount) lens used in this topic:

Sigma 24-70mm F2.8 DG DN (E-mount) sample gallery 

[John R Ellis]

Lens-profile corrections behave differently when applied to a raw and a lossy DNG converted from that raw. But lens corrections behave the same when applied to the raw and a lossless DNG converted from the raw.  This contradicts the received wisdom that there are no perceivable differences between lossy and lossless DNGs.

To reproduce on LR 13.5 / Mac OS 14.6.1:

1. Download and open this catalog:

https://www.dropbox.com/s/rzt5qxmlzizu3v6/lens-corrections-dng-bug.2024.08.22.zip?dl=0

It contains a raw .arw and 6 perspicuously named DNGs created from the raw using Library > Convert Photo To DNG, with compatibility set to 12.4, 14.0, and 15.3, with and without lossy compression. Lens profile corrections are enabled on all 7 photos.

2. Select the .arw and the 15.lossy.dng and go to Develop.

3. Do View > Lock Zoom Position and zoom to  a corner at about 500%. Switch between the two photos and observe they are not identical, with one shifted relative the other. Repeat with the other corners.  Then zoom to the center of the photos and observe they are nearly identical.   See the attached screen recording.

4. Repeat the previous two steps with the raw and 15.no-lossy.dng. Observe that the photos are identical.

5. Repeat these steps with 14.lossy/no-lossy.dng and 12.lossy/no-lossy.dng, observing the same results.

[John R Ellis]

@Rikk Flohr: Photography, please consider moving to Bugs.  See my previous reply above for a concise bug description and recipe.

[John R Ellis]

@Guo_XM, as you've seen, the issue occurs with lossy DNGs but not lossless DNGs. Unfortunately, LR's Photo Merge and Denoise create lossy DNGs and don't provide an option to create lossless DNGs. The only workaround I can think might work is to apply lens corrections to all the raws first and convert to TIFFs, then use Photo Merge on the TIFFs. You shouldn't lose any noticeable image quality with that workflow, though it would be much slower.

[Bob Somrak]

@John R Ellis said

"In some quick testing, I've observed that Auto Align of a raw merged with its identical virtual copy produces a result that is unaligned with the original by a few pixels vertically and horizontally."

I have observed the same situation in Photoshop.  I have imported the SAME image as layers an aligned them and they are a couple pixel off.  If I do the alignment again it is sometimes correct.