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by Bart Arondson

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10

Are you working with RAW or JPEG? RAW will not use the in-camera correction but JPEG will.


10

The lens corrections aren't part of the firmware itself (i.e. a particular firmware doesn't mean you have a particular lens correction). They are profiles that can be stored in the camera, and you need to register them with the camera if they aren't in the default set. Canon DSLRs that support lens corrections (Peripheral Illumination and/or Chromatic ...


10

Most post-process lens corrections will cause a loss of detail, as they are not just modifying how the raw pixels are interpolated and what mathematical curves and adjustments may be applied...they change the position of pixels throughout the whole image. At the very least, you'll lose some amount of sharpness, and fine detail may be lost in some areas of ...


6

To answer the first part of your question: As wikipedia says, it is for correcting lens effects, such as barrel distortion and and perhaps more important vignetting. Basically it is data about a lens that is applied to an image, a lens that is known to have -1EV of vignetting at the edge of the photo will be corrected by applying +1EV at the edges. Or if ...


5

Disclaimer: I haven't worked in a wet darkroom and so all of this is from theory. Not really. The enlarger itself was a rather simple setup. It also works with a rather shallow depth of field (though one tends to stop down 1 to 3 stops from wide open to avoid aberrations in the enlarger lens (depending on the lens itself)). The depth of field in the ...


5

Pincussion or barrel distortion is corrected to the ideal rectilinear lens of the appropriate focal length, one that obeys the pinhole projection model perfectly (all straight lines remain straight). It's an unambiguous correction (I.e. there is one right answer). The image will be copied to a rectangle, altering the effective focal length.


5

As far as free alternatives you can try Fred's defisheye script for ImageMagick, or Fulla, which is a command line tool that comes with Hugin. Fisheye-Hemi is superior to these, though, as instead of using a standard remapping to a rectilinear projection that softens the edges and requires an aggressive crop it uses a custom mapping algorithm that preserves ...


4

I use Gimp and the MathMap plugin, together with a few scripts of mine to convert the fisheye image into whatever projection better fits the subject: either rectilinear, stereographic, or Mercator. Mercator is my favorite: it's a kind of panoramic cylindrical projection that looks quite similar to the Fisheye-Hemi projection and is free of local distortions ...


4

I've done comparisons using my Canon EF-S 17-55mm F/2.8 IS USM lens turning the profile on and off, and I can't actually notice any drop in sharpness as @jrista stated. I guess it would depend on the lens being used, but for that lens I automatically apply the lens profile on import. It gets rid of noticeable vignetting as well. I expected some slight ...


3

You got some great answers to your first question already which I'll summarize as: Lens correction attempts to compensate for lens defects. As for whether it is important or not, it depends on several factors: One is the lens in question, a perfect lens obviously would need no such correction but there are plenty of high quality lenses which get ...


3

Lens correction is based on mathematical model that describe how a ray of light moves from the ideal frame to the lens distorted frame as a function of the point's distance from the principal point (center). Note that this center is not width/2 , height/2. It needs two sets of numbers: camera matrix and distortion coefficients. Last time I looked at ...


3

If you shoot RAW, the in-camera lens correction is not directly applied to the RAW data, it is appended to the tagged data. The lens correction is applied to the in-camera preview JPEG thumbnail viewed on the camera's screen. If your selected camera output is JPEG then the in-camera lens correction is applied at the time the file is processed in camera. As ...


3

No, MS ICE does not have a lens database AFAIK. It really does not matter much since it has to distort the images to make features match and perform blending. In my experience success is generally high but not perfect. I would try straight with ICE first because any processing you do before hand always adds image quality loss. If it fails, then try it after ...


3

Lens correction is off by default - you have to check a box to turn it on for an image, or set of images. This is in the Develop view, under the Lens Corrections panel. The Enable Profile Corrections is the toggle.


2

When in Develop, there is a Lens Correction panel. Within this panel you can turn profile lens correction on or off using the Enable Profile Corrections checkbox


2

According to Canon, Digital Photo Professional writes additional information for the DLO processing to the RAW image; the result is that the RAW image file will increase in size, often significantly. It saves not only the new corrected image in RAW format but also the original image into the file - or at least the steps taken to get from the original ...


2

Actually you can check the list of supported lens profile directly to the adobe site. The contax lenses seems not yet supported. In this case you have three alternatives: Submit a request in the feedback.photoshop.com and waiting for Adobe implements in the new release of camera raw Create a lens profile by yourself using the lens profile creator by ...


2

In Lightroom there are various settings that come under the 'Lens correction' umbrella. The 'Enable Profile Corrections' flag will correct the image based on the type of lens it was taken with, so if you copy it from an image taken with a 10mm lens onto an image taken with a 20mm lens, it will correct the latter for distortions caused by the 20mm lens. If ...


2

Perspective correction is possible in a film/enlarger/paper process, by setting up the paper in a non-parallel relationship to the film. The paper is typically held by an easel which holds it flat. Propping up the easel on one side brings the paper closer to the enlarger head on that side, which in turn increases both magnification and exposure on that ...


2

Light fall-off depends on a particular lens at a certain aperture and for some focal-length. There are a number of cameras which can do this but they must be able to recognize the lens. This is a profile based approach and can usually be enabled some cameras with electronic lens mounts. A few other cameras allow to apply an amount of compensation, probably ...


1

Some cameras now have lens correction features built in, but many do not. And sometimes those corrections extend to light fall off, but not always. For example, the Pentax K-5ii and a few prior models correct for distortion and lateral chromatic aberration. The K-3 adds "Peripheral Illumination" to correct light falloff in the corners. More on this in the ...


1

If you shoot raw then YES you will need to use the lens profile option in Lightroom.


1

You can use as reference the document Calibration Chart Shooting Guide for the Adobe Lens Profile Creator. In the advanced setup you can see that it is possible to shot data for several aperture and several focal length. Of course if the data set is not complete lightroom engine will interpolate the missing data. For the supported lens supplied with ...


1

I don't know if one already exists, however you can make your own if you don't mind putting in some effort. Adobe has the "Adobe Lens Profile Creation" utility which allows you to print a black and white checkerboard grid which you can then photograph and use to build a profile. The documentation for the utility is available from Adobe's website here. The ...


1

Lightroom uses the make and the model of the lens to filter the list of displayed profiles, as determined from the EXIF data or selectable from the drop-down lists, as well as the file type (RAW or JPEG). you can see (and edit, if you are adventurous) these parameters n the .lcp files, i've successfully used a profile created for JPEG for my RAW's. (this, of ...


1

The corrections deal with a set of aberrations that the lenses have due to optical imperfections in design and production. Each aberrations are described with equations, which are used to correct the images into how the images would have looked if the lens did not have these aberrations in the first place. Reading your questions it looks like you think it ...


1

If you shoot RAW, you can let Lightroom-4 handle all the corrections, color and all flavors of lens distortion (barrel, mustache, color fringing, etc.) You can have it done automatically or tweak the settings as @dan suggested. I am very happy with the abilities in LR4. It can even correct geometry distortion typically found in architectural photos when you ...


1

There is another software (although not free) called PTlens that does the same for a wide range of lenses. See their example page to see what it does.


1

When you correct lens distortion, the rectangular image is warped into a non-rectangular shape. Since we generally want our finished images to be rectangular, the image is then cropped to a rectangle that fits inside the warped shape. This means that objects near the edge of the original image may be cropped out of the finished image. That's a trade-off that ...



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