Resolution of M43 lenses

Started Mar 31, 2013 | Discussions thread
Anders W
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Re: Demonstration of Differences in DxO Geometric Corrections
In reply to Detail Man, Apr 2, 2013

Detail Man wrote:

Anders W wrote:

Sure. DxO crops the image to a rectangular shape. If you ask LR kindly, I think it will do the same. Or if you ask DxO kindly, it might abstain from the cropping, which from a diagnostic point of view might be even better. If additionally, you make sure that the amount of correction applied by the two converters is exactly the same, it might be an interesting comparison.

OK, magister, I have now cropped the Adoobie image down to the girlie-man size of a mere 3499x2624 pixels (seemingly all that it could handle), and gratiously lowered the DxO Optiques Prose image size to a similar puny dimension. Once again, download the Original images and display them in an image-viewer at 20% size (collapsing 5x5 pixel arrays into single, centered pixels).

Lightroom 3.6:

Note the pattern that appears to imply a single centrally placed optical correction reference point.

.

DxO Optics Pro 7.23:

Note the four circular patterns that appear to imply four separate correction reference points.

I anxiously await your refutations showing that Adobe is the embodiment of crystalline perfection.

Note: The DPReview post-display system appears to be malfunctioning. This is my 2nd and final possible edit. If images do not display, click on the Gallery Page links to download the Originals.

DM ...

I see all kinds of interesting moiré patterns depending on the magnification of the image itself as well as display magnification. But I wouldn't want to make anything out of that.

Now if you really want to test this DM, one way of actually getting somewhere without a whole lot of work would be the following: Take your test image, distort it using the one RAW converter, output it, and then try to undistort it using the other RAW converter. If the algorithm is essentially the same, you should be able to come back to square one, i.e., the pure, straight, column-row pattern that you started out with (though perhaps a bit degenerated in ways that are for present purposes a bit irrelevant). If not, then you shouldn't. For safety's sake, you might want to approach the matter from both ends, distorting with LR and undistorting with DxO, distorting with DxO and undistorting with LR.

My guess is that when you just use the main distortion slider of the respective RAW converter, they will for all practical purposes do the same job. When working on the basis of lens profiles, however, things may well stand differently. In that case, both may make use of more than a single parameter to correct more complex forms of distortion, and the parameters they use may be different.

Note: I don't know how you create the synthetic RW2 that you are playing with. But it should obviously not be such that either RAW converter tries to apply any distortion correction by default. Any distorting or undistorting should be done by you via the sliders.

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