Comparing two images at the same resolution

[RoyPrasad]

LRC provides the ability to compare two images side-by-side, but the functionality would be far more useful if we can compare two images at the same target output resolution.  It makes no sense to compare an image from a Hasselblad X2D 100C (100 MP) with an image from a Leica M11 (60 MP) at actual pixels.  It would be much more valuable to see the two images with the larger image scaled down to the same resolution as the smaller image, using the long-dimension as the reference.  Or see both images scaled to a target ouput size, like 6000 pixels on the longer dimension.

If LRC already does this, I'd greatly appreciate it if someone could let me know how.  Thanks in advance.

[JohanElzenga]

I don't think you can do this in Compare view in the Library module, but you can (more or less) do it in Reference view in the Develop module, using a trick. Setup reference view, and zoom in on the active photo as far as you want. Then use Cmd-drag in the reference photo to zoom in to the same view by drawing a rectangle over the area that fits the view of the active photo.

[RoyPrasad]

Thank you for taking the time to respond.  That ddid work in terms of setting up nearly identical magnification for the two images.

Problem with it is, it's very painful to scroll.  You want to do things like compare things like sharpness, microcontrast, aberrations, etc. at different parts of the frame, like the left edges, top right corner, or on specific features in the image.  So navigating through both images is slow and painful.  It is much quicker to output two images as JPEGs, both at the same output resolution (e.g., the resolution of the smaller sensor), then import the two JPEGs as two new files into LRC.  At least, I can do the compare much more easily.  Obviously, I would not want to make any further edits to the JPEG versions, so if I needed to tweak either image, I'd have to go back to the raw file and make the edits there.  So it is clumsy, but at least, once I bring in the two JPEGs, I can easily navigate through the images to do may comparisons.

It would be a lot more efficient if LRC could provide further options within the View-->Compare function.

It would also be very useful to do things like crop either image or tweak the WB of either image, so two images can be matched in terms of their overall parameters.

Roy

[Conrad_C]

Although there’s nothing wrong with the idea, it’s unlikely that they’ll add it any time soon. Like similar photo editors from other companies, Lightroom Classic avoids previewing most output-referred adjustments such as ppi and resampling (e.g. to the same 6000 px long dimension). The only output-referred preview I can think of that Lightroom Classic does is soft-proofing.

If you need to do this soon, it will be better (although not convenient) to open the images side by side in Photoshop. You’ll be able to view both images at 1:1 (the View > 100% command), or at print size corrected for ppi (the View > Actual Size command). And you’ll be able to resample either image to whatever long dimension you want, and compare that.

Also, In Photoshop, the Hand tool and Zoom tool support synchronizing moving and zooming all open document windows. Just enable the Scroll All Windows and Zoom All Windows option in each tool’s options bar, respectively.