LX7 awful edge resolution due to distortion correction

Started Apr 30, 2013 | Discussions thread
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Detail Man
Detail Man Forum Pro • Posts: 16,666
Re: PTLens

technic wrote:

Detail Man wrote:

technic wrote:

I don't have experience with this combination, but in general PTLens also does a good job for distortion correction, resulting in much better corner sharpness than LR/CR or in-camera processing. Probably those more complicated distortion corrections cannot be done in-camera at the time.

Not familiar with what PTLens does either (the profile-data is collected by individual users from characteristics of their own individual units). If it uses the same process that the Panasonic image-file meta-data uses, I think that it is a fairly simple correction algorithm that proceeds from a single point located at the center of the image-frame, the identity for which is shown here:

PTLens does NOT use a simple algorithm but more complex functions which can fully correct moustache distortion (unlike the algorithms in LR/ACR and most other RAW converters and in-camera processing).


However, AFAIK it uses fixed parameters for a certain lens (focal length) normally calibrated at infinity focus, and does not correct for changes in distortion with focus distance (potentially DXO can do that, but it's not clear to me if/which of their software really uses this).

Not clear to me, either. Not so for the LX3, but for the LX5 and GH2 (becaue most Panasonic cameras do not include information estimating Focus Distance in their image-file meta-data), DxO has a control-slider for the user to input an estimated Focus Distance.

Have not seen the value of Focus Distance entered alter the Rectlinear Distortion correction. At certain specific "steps" between input Focus Distance values, the "Lens Softness" corrections cause the previewed image to shift the position of the previewed image slightly. Thus, I think that it may only be the "Lens Softness" corrections that are altered by Focus Distance estimate input by user.

Took a look at the demo here:


That looks interesting. The OP already uses LR, so that might be a more desirable option for them.

The only potential issue that I would see is that the profiles (similar to the Adobe LR/CR custom lens profiles) are derived from individual volunteer user test data submitted. Thus, they (may) not represent a good statistical sampling of the existing units (something that I assume that DxO Labs does do when creating their DxO Optical Corrections Modules). The other concern is that it is possible that those individual users (may) not have performed the testing properly.

That said, I am not trying promote DxO Optics Pro, I assume that you are not trying to promote PTLens (as it sounds like you have not yourself used it - at least in the case of the LX3, LX5, or LX7 ?), and "the proof of the pudding is in the eating" where it comes to actual results.

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