P: Perspective correction from Camera metadata not supported for Leica Q3

[Wilson Laidlaw]

When perspective correction is selected in camera for the Leica Q3 (I have it set to On/Off on the Q3's option button #2), this does not appear to activate in LR Classic when converting the DNG, using the camera's image metadata. Only manual perspective correction appears to be available, which makes the camera feature rather pointless. I am using LR Classic (V 13.0.1) on an M2 MacBook Air with 16GB RAM and with Sonoma 14.0 Operating System. Profile corrections does not list the Leica Q3 but only the M, R and S models. 

[johnnyw]

LRc (and LR) doesn't seem to be interpreting the auto perspective correction metadata in the Leica Q3.

With the Leica M11 you can automatically apply the perspective correction using "Guided" in the Transform panel, but this isn't working for the Q3.

Not sure if this is a bug or a feature request.

[johnrellis]

I found one thread with several people complaining they weren't able to get LR to recognize perspective corrections supposedly added by the Q3 to the DNG.

Upload a sample DNG taken with perspective correction to Dropbox, Google Drive, or similar, and post the sharing link here. I can put it under the microscope to determine authoritatively if it contains the correct metadata specifying the perspective correction (i.e. whether the problem is with LR or the camera).

[johnrellis]

Also, I couldn't find any downloaded Q3 sample DNGs that were advertised as taken with perspective correction enabled.  

At the Leica web site, I did find several downloadable sample Q3 DNGs that clearly had perspective corrections applied to them. However, when I downloaded the DNGs, their metadata indicated they been edited in LR 12.3 and had Transform > Auto applied! Transform > Guided had not been added automatically by the camera. Suspicious.

[johnrellis]

There was a previous post about this recently:

https://community.adobe.com/t5/lightroom-classic-discussions/leica-q3-auto-perspective-correction/td...

though the person never responded to my request:

"Upload a sample DNG taken with perspective correction to Dropbox, Google Drive, or similar, and post the sharing link here. I can put it under the microscope to determine authoritatively if it contains the correct metadata specifying the perspective correction (i.e. whether the problem is with LR or the camera)."

Adobe is much more likely to respond to a bug report that includes a sample photo and an analysis showing the issue is with LR and not the camera.

[Wilson Laidlaw]

Here is a Leica Q3 DNG with perspective control on https://www.dropbox.com/scl/fi/6jaj975eod346w1wmjxwj/L1000133.DNG?rlkey=wc681x7ccdy8bn29n1icn500s&dl... 

[richardplondon]

Can you please clarify more exactly - by "perspective correction" do you mean Perspective Control, or Lens Correction? Your question states "profile corrections does not list the Leica Q3" - which seems to suggest the latter.

As I understand it - not a Leica user, so please take with a pinch of salt - Perspective Control will have been already baked into a camera JPG. So far as a camera raw (camera DNG included), the camera has not transformed the Raw data or - not sure - may not even have encoded in any particular "recipe" for transforming perspective. Some proprietary metadata likely records that Perspective Control had been asked for.

LrC either then pays attention to that request or doesn't - it seems support varies by model.

AFAICT LrC would deliver any 'perspective controlled' result, if it was going to do so, by turning on its own Upright auto transform. I doubt Adobe has reverse engineered the exact proprietary means of perspective correction of each camera model. Many cameras don't offer such a feature themselves anyway.

Upright can be turned on/off manually inside LrC. Or in processing defaults, a preset, etc.If you leave Perspective Control off in-camera then both camera Raws and camera JPGs will arrive in LrC without such correction baked in. You can then set or change this correction for yourself nondestructively.

In-camera perspective adjustment  and LrC's Upright may conceivably vary depending on what analysis each one makes of the photo. The nice part about invoking this correction via Adobe adjustments, rather than obeying some fixed "recipe" coming from the camera, is that you can intervene when the default auto solution doesn't quite give what you want.

[Wilson Laidlaw]

Basically I am not an LR user, having used C1 for the last 20 years but as Phase One advised me that they do not currently recognise Perspective Correction when turned on in camera nor do they recognise when preselecting in camera lens focal length cropping, I turned to LR, where Leica claimed they had been working with Adobe to get this data which is included with the metadata of the image, applied to the image when it was opened in LR develop module. It appears neither is being applied. The in camera perspective correction supposedly applies the keystone correction which appears as an outline in the viewfinder when taking the image. As I have no idea how Leica intended or intends this to work, as no further information has been supplied by Leica, I have tried searching through the various functions in LR to see if any of them applied a keystone correction to a pre-set level. It appears none of them do, although (as in C1) I can apply keystone correction manually. As the auto correction function does not appear to be present, I cannot comment on where if ever, it will appear. The same applies to the cropping function. 

[richardplondon]

The only focal length cropping I have experience of, is when a crop format lens is mounted on a full frame body. That's more accurately a sensor coverage issue, not a focal length issue. The camera can be set either to pass on the entire full frame image, or the designed coverage of the crop lens. I think LrC will usually respect this. So far as "digital zoom", if that is what you are referring to, that is a sensor coverage not a focal length question also. I don't think "digital zoom" has ever affected Raw data in my personal experience - which is not the widest, I am the first to admit.

Inside LrC as you've discovered there are manual transforms including for keystoning, as well as manual lens correction options. Those apply values that are repeatable onto other images. The generic distortion and vignetting would be fallbacks in the event that proper profile based lens aberration correction was not available. The transforms work with a "constrain crop" checkbox which if unchecked, allows any white corner margins to come into view as the transform alters the current main crop. Manual treansforms could be fallbacks if Guided and Upright were not found suitable. But Upright, falling back to Guided in difficult cases, are far the more productive and predictable options in my experience compared with the manual sliders.

Upright mode offers various kinds of intended correction . These work off the appearance of the photo only.  Which option you choose here might be thought of as a "preset level" of intervention - though I am unsure what you precisely mean by that form of words.

Auto is IMO excellent at getting to the best-compromise result, on balance, in one go. It is flexible not prescriptive. So if nearly parallel things will likely become fully so; but if quite convergent, that may be assumed to be intended or else that it would be too big a correction to still remain natural looking. You can instead choose a more specific Upright mode, which concentrates more single-mindedly on Level / Vertical / Full. Full tries much harder to force both what it analyses as horizontals, and verticals, orthogonal. That can often turn out to need very obvious, extreme warping to achieve. But useful for some special purposes.

And Guided upright gives you close interactive control per image.

So far as transferring onto other images, EITHER you can impose a repeat of the same Upright mode selection (with a specific transform to be analysed afresh for each target image) OR an Upright or Guided solution (repeating the same specific transform from the source image).

[johnrellis]

[This post contains formatting and embedded images that don't appear in email. View the post in your Web browser.]

I researched this issue and concluded that LR doesn't support the perspective control of the Leica Q3, though it does for other Leica cameras.

I think your best bet is to contact Leica support. As a premium high-priced brand, I think its support should be much better than Adobe's (which, like any other large corporation, is horrible with respect to detailed technical issues). Adobe is much more likely to pay attention to its business partner than to a mere LR customer.

Good luck in getting a straight answer from Leica or Adobe.

Details

When the perspective control is enabled in some Leica cameras, the camera uses its position sensors to compute a perspective correction.  It applies the correction directly to JPEGs, but for raws (DNGs) it records the correction parameters, which software like LR can use to apply the correction.  

This approach can produce superior results compared to methods like LR's Transform that look for vertical and horizontal lines in the photo.  Some photos don't have easily detected lines, and sometimes the detected lines aren't true indicators of  vertical and horizontal declinations.

The Q3 manual says:

"JPG FORMAT IMAGES

"For JPG format images, the correction occurs directly in the camera and only the corrected image is stored. Any image content outside the frame will be lost.

"DNG FORMAT IMAGES

In DNG format, the entire sensor image is stored unchanged. The data calculated by Perspective Control is written to the meta data of the image. Image correction is done later, using appropriate software like Adobe Photoshop Lightroom® or Adobe Photoshop®*. A corrected preview version of the image (thumbnail) is displayed in review mode. The same applies for automatic review directly after the image is taken."

The perspective controls on other Leicas behave similarly.

This LR Help article explains how to apply the Leica's perspective correction for supported cameras:

https://helpx.adobe.com/camera-raw/using/leica-perspective-control.html 

In LR and Camera Raw, you enable Transform > Guided. LR will automatically compute four guidelines from the correction metadata recorded in the DNG.

The article says that just three cameras are supported: M10-R, M10-P, and M10 Monochrome. I couldn't find any samples online from these cameras with perspective control enabled. However, I did find this sample from an M11 Monochrome with the control enabled:

https://www.dpreview.com/sample-galleries/0809548205/leica-m11-monochrom-sample-gallery/8351345466

In LR, clicking Transform > Guided makes a modest perspective correction to that image. Exiftool shows that the camera recorded this Leica-specific metadata:

xmlns:xmpDSA="http://leica-camera.com/digital-shift-assistant/1.0/"
xmpDSA:Version="1.0.0" 
xmpDSA:CorrectionAlreadyApplied="False" 
xmpDSA:PitchAngle="-0.4490000010" 
xmpDSA:RollAngle="1.0299999714" 
xmpDSA:FocalLength35mm="28.0000000000" 
xmpDSA:TargetAspectRatio="1.5000000000" 
xmpDSA:ScalingFactorHeight="0.9733870625" 
xmpDSA:ValidCropCorners="True" xmpDSA:ApplyAutomatically="False">
  <xmpDSA:NormalizedCropCorners>
    <rdf:Seq>
      <rdf:li>0.0059584188</rdf:li>
      <rdf:li>0.0263321400</rdf:li>
      <rdf:li>0.9823713303</rdf:li>
      <rdf:li>0.0000000000</rdf:li>
      <rdf:li>0.9908543229</rdf:li>
      <rdf:li>0.9732784033</rdf:li>
      <rdf:li>0.0208045542</rdf:li>
      <rdf:li>0.9994389415</rdf:li>
    </rdf:Seq>
  </xmpDSA:NormalizedCropCorners>

The camera has recorded the camera pitch and roll angles and the coordinates of the four corners of the "keystone" trapezoid that should be transformed to a leveled rectangle.

In addition to the Q3 sample provided above by @Wilson Laidlaw, I found lots of Q3 DNGs with perspective control enabled, e.g.

https://www.dpreview.com/sample-galleries/9356330178/leica-q3-sample-gallery/9228357800

https://www.dpreview.com/sample-galleries/9356330178/leica-q3-sample-gallery/8966924984 

https://www.dpreview.com/sample-galleries/9356330178/leica-q3-sample-gallery/9228357800

https://www.dpreview.com/sample-galleries/9356330178/leica-q3-sample-gallery/5249711965  

They all had the same metadata fields recording the camera's corrections. But when you click LR's Transform > Guided, nothing happens -- LR isn't recognizing the corrections. 

The Q3 isn't listed as a supported camera, but neither is the M11 Monochrome, which LR does support. The Help article is dated 1/12/22, long before the Q3 announcement on 5/25/23. But that alone isn't dispositive -- Adobe documentation is often out-of-date.

It should be trivial to add support for the Q3 to LR, since the correction metadata is exactly the same and there's nothing camera-dependent about the correction.

Q3 Examples

To prove that the Q3 samples contain valid perspective-correction metadata, I wrote a script (appended below) that extracts the Leica correction metadata and converts it to Transform > Guided develop settings.

Here's what the keystone correction looks like with @Wilson Laidlaw's example, before and after applying it via Guided:

This is a little bit better than Transform > Auto.

Here's another example from the list above:

The Q3's correction does a much better job than Transform > Auto at getting the grass in the lily pads vertical.

Conversion Script

Here's the Lua script I wrote that converts the Leica's XMP:NormalizedCorners metadata to LR's Transform > Guided develop settings. The script requires my plugin development framework, and unfortunately, given the small potential audience, I can't justify the effort required to produce a full-fledged, supported plugin.

local ExifTool = require "ExifTool"

local corners = ExifTool.readFieldsFromPhotos ({targetPhoto}, {"XMP:NormalizedCropCorners"})
    [targetPhoto].NormalizedCropCorners

local ulx, uly, urx, ury, lrx, lry, llx, lly = unpack (Util.arrayMap (
    Util.split (corners, ", "),
    function (s) return tonumber (s) end))

local s = targetPhoto:getDevelopSettings ()

s.PerspectiveUpright = 5
s.UprightFourSegmentsCount = 4
s.UprightFourSegments_0 = table.concat ({ulx, uly, urx, ury}, ",")
s.UprightFourSegments_1 = table.concat ({urx, ury, lrx, lry}, ",") 
s.UprightFourSegments_2 = table.concat ({llx, lly, lrx, lry}, ",") 
s.UprightFourSegments_3 = table.concat ({ulx, uly, llx, lly}, ",") 

Util.withWriteAccessDo ("", function ()
    targetPhoto:applyDevelopSettings (s)
    end)

[johnrellis]

@Rikk Flohr: Photography, please consider moving to Bugs. Adobe's partner Leica says that Lightroom will recognize perspective corrections made by its Q3 camera, but as I discuss above, LR ignores such corrections. 

[johnrellis]

Moderators, @Rikk Flohr: Photography, please merge with this thread:

https://community.adobe.com/t5/lightroom-classic-discussions/perspective-correction-from-camera-meta...

[Wilson Laidlaw]

Many thanks folks for helpful posts. I think Leica are now at the stage of running and hiding under their desks, when people raise the absence of auto correction for keystoning on the Q3 when importing a DNG image into LR with perspective correction turned on in the camera. The Leica community, where I have been a member for many years (third generation Leica user, myself for over 60 years but family for 90 years), given the price of their Leica cameras, are far from shy about letting Leica know of any perceived shortfalls on either the camera or its coupling to RAW recommended software. I will now have a go with my M10-R as you advise that is working with the guided feature in Transform on the Develop module. 

[richardplondon]

Pragmatically, until perspective support may arrive for this camera the same as for other Leica models, perhaps Vertical might be a better mode to try within LrC's own Upright panel, than Auto? If anti-keystoning is a priority.

[johnrellis]

"I will now have a go with my M10-R as you advise that is working"

Note that I wasn't able to test any of the three cameras documented by Adobe as being supported, including the M10-R, since I couldn't find any samples with perspective control enabled.  I did find such a sample from the M11 Monochrome, with which LR worked correctly. So be sure to test first, and/or post a sample here.

[Rikk Flohr: Photography]

Moving to feature requests as this is a not-yet-supported feature for this camera.

[johnrellis]

@Wilson Laidlaw, sounds like Leica needs to be informed of this authoritative information from Rikk Flohr.

[srdjanmitrovic]

Per Leica's email from August 7th, Leica engineers were working with Adobe engineers on fixing it. Note that Adobe supports LPC for all other Leica cameras that have it. Leica expected that LrC 13.0 would contain the fix (per email from October 12).

[johnrellis]

Good to share this information here, since there have been others asking too.  I'm not sure what the technical hang-up is, since I wrote the script that translates Leica correction metadata to LR corrections in about 45 mintues.

[Wilson Laidlaw]

Offer to sell your routine to Leica, so that they can pass it back to Adobe. 

[johnrellis]

"Offer to sell your routine to Leica, so that they can pass it back to Adobe."

😆 No need to sell it, the important details are visible to all.  But you could link to this thread in teh Leica forums.

[Wilson Laidlaw]

Already done. 

Wilson

[Rikk Flohr: Photography]

Support for this Leica feature is now available in Camera Raw 16.0.1 released this morning. Please refresh your Creative Cloud App to see and install the update. 

[Wilson Laidlaw]

Just to let folks know this update to Camera RAW to enable prespective correction for the Leica Q3 when in the Metadata, does not seem to appear automatically as usual. You have to refresh the updates by clicking on the "Check for Updates" button. V.16.0.1 then is offered. 

[srdjanmitrovic]

Thank you, Rikk. I can confirm that it works with ACR. Do you know when we can expect an LrC update as well?

[srdjanmitrovic]

The November 2023 Lightroom update still does not support perspective control for Q3 :(.