Helicon Devignetting

HeliconDevignetting_medium2

Helicon Devignetting is a professional tool for correction of peripheral shading (vignetting).

It is a program for perfectionists. It is designed to correct vignetting for specific lens at hand, not for a generic lens of this type.

The program primarily works with RAW files and saves results as DNG files (RAW-in-DNG-out workflow), which ensures that all the details, colors and extra information is left intact for the next stages of post processing.

Why to choose Helicon Devignetting?

Many modern cameras can automatically compensate vignetting, many software packages are also capable of doing so. Why bother creating your own devignetting maps?

  • Every lens copy is slightly different, which means that generic profile might not perfectly match your lens. For example, often vignetting is not symmetrical (see the screenshot above).
  • Use of lens filters, extension tubes and hoods may change vignetting profile.
  • Many 3rd party and manual lenses have no predefined vignetting profile.
  • Corrected images can be saved to DNG format, preserving all RAW information.

 

Overview of Helicon Devignetting workflow:

  • Create a set of devignetting maps, shot with your camera and lens
  • Import maps into Helicon Devigetting library
  • Apply corrections to one source file or the whole folder
  • Save results as DNG, TIFF or JPEG files

Creating devignetting maps

To create maps for your lens, you need to take pictures at different apertures and focusing distances.

shooting_dv_map

  • Fasten a sheet of paper or plastic on the window
  • Set your camera on a tripod and position it so it touches the paper sheet with the lens thread or hood
  • Focus to infinity, select RAW format, switch to aperture priority mode, focus set to manual
  • Take pictures at different apertures and zoom levels

Camera parameters for devignetting maps:

Vignetting is usually stronger at open apertures so we recommend to take more pictures with open apertures. Also vignetting depends more on aperture then on focal length, so aperture will require more samples. Here is the example of parameters to create maps for Nikkor 14-24 lens:

f2.8 f3.2 f4 f5.6 f8 f13 f22
14mm x x x x x x x
18mm x x x x x x x
24mm x x x x x x x

 

Selecting the right plastic or paper

It is important to use sheets of paper or plastic which are homogeneous.

paper_types_contrast

As you can see, office paper (1)  is not good at all - too many clumps which are hard to smooth.
Tracing paper (2) is almost perfect, very homogeneous with fine texture.
Plastic folder (3) is also very good, constant density all over.

In most cases you will need to use several sheets of paper to get rid of the gradient caused by skyline. To check this, take one image in normal position, then rotate the camera by 180 degrees and take another shot. Compare the two images by switching back and forth between them in the camera. If there is no difference then the diffusing filter is good enough.

 

Command line mode

Helicon Devignetting can be called from other applications in "silent" mode.

Command line parameters should be passed using the following convention:

HeliconDevignetting.exe -silent [-log] "source_file" [-i:N] ["-s:target_file"]

-silent = activates silent processing instead of opening of program window
-log = (optional) allows to save processing details to text file
source_file = path to source file
-i:N = (optional) intensity N [0..100] -s:target_file = (optional) target file name

Examples:

HeliconDevignetting.exe -silent "my_raw_file.nef"
Result will be saved to the same folder with the format defined in Queue window

HeliconDevignetting.exe -silent "my_raw_file.nef" "-s:с:\my_res_file.tif"
Result will be saved to с:\my_res_file.tif

HeliconDevignetting.exe -silent -log -i:20 "my_raw_file.nef" "-s:my_res_file.jpg"
Processing with intensity 20, saving result as my_res_file.jpg, log file is created

 

Downloads

Heliconn Devignetting is now in beta testing stage and you are welcome to join.

Your feedback is welcome. Active beta testers will be provided with free license.

Compatible with Windows 7, 8, 10

HeliconDevignetting.exe (82M)

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