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12 Messages

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326 Points

Sat, Jul 23, 2011 10:02 AM

Lightroom: More lens profiles for jpegs

More lens profiles for jpeg-photos, please!

At the moment in contrast to RAW-profiles there are only few lenses for distortion correction in jpeg-photos available.

1

Responses

946 Messages

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13.8K Points

9 years ago

It's a tough problem. JPEGs can be modified by the camera in many ways, mostly unknown to the converter. What if the JPEG has already been vignette and geometry corrected by the camera? What if it's just had CA removal? What do you do about no knowing the in-camera settings?

I've posted previously how to modify any raw profile to make it work on JPEGs, and in some cases it works okay.

12 Messages

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326 Points

I don't know any DSLR that corrects optical shortcomings such as vignetting, barrel-distortion or CA so creating profiles for JPEG should be as easy (or hard) as for RAW.Actually in LR3 there are JPEG related profiles avaliable for some lenses so it seems to be possible.

946 Messages

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13.8K Points

Even if that were true, the vignetting correction is sensitive to in-camera settings like contrast.

230 Messages

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4K Points

The Canon EOS 5D MkII does correct vignetting when building a JPEG, if you tell it to do so (and yes, it's based on a lens-profile also).

Beat

Employee

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626 Messages

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11.4K Points

Unfortunately it's hard to build a robust solution for jpegs. You've already mentioned one issue, which is corrections already applied by camera (sometimes they do it, sometimes not). The file may not have metadata to indicate whether the corrections have already been done. Another problem is dealing with cropped or resized jpegs (hard to tell the difference); in other words, the physical size of a pixel is not known with jpegs, and this physical unit is necessary to apply the lens correction model (we need to relate pixels in the image to physical distances on the image circle, e.g., in mm or cm).

513 Messages

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11.1K Points

9 years ago

Kilian, the Pentax K-5 is just one example for a camera that will -- on request -- correct vignetting, barrel-distortion, and CA for certain lenses.

In any event, however, I don't understand why in-camera corrections and/or potential cropping are stumbling blocks. If they were showstoppers then no JPEG lens correction profiles should exist. Yet, they do and for a good reason, because in many cases they can be helpful. The simply request was -- as I understood it -- to place this support on a wider footing.

AFAIC, the real answer is to abandon JPEGs and shoot RAW. It has many advantages beyond the availability of lens profiles. The only reason I can think of in favour of using JPEGs is speed. If the speed requirement goes beyond burst rates of cameras then I'd suggest that LR isn't the right tool anyhow.