The Levelizer Filter is designed to compress the tonal range of images to
allow both bright and faint detail to be seen. This process is normally
done manually in Photoshop using masks and duplicate images. The Levelizer
automates the process, making the task simple and rapid, and allowing an easy
preview of the results. For more details,
Filter product page.
How the Levelizer Filter Works
The Levelizer automates the process of creating a mask to enhance faint
details in an astrophoto. The filter allows the user to control the mask
settings which determine the areas of the image to be enhanced (the faint parts)
and the areas to be left alone (the bright parts). The mask settings can
be easily altered to control how much enhancement is applied and to which parts
of the image.
Processing Images with the Levelizer Filter
Above: Original unprocessed image of the Lagoon Nebula
Begin by opening an image in Photoshop, then open the Levelizer window by
going to Filter > Starizona > Levelizer.
Above: Default settings for the Levelizer Filter
The default settings are often quite good (that's why they are the defaults,
after all), but this tutorial will show each setting individually so you can
understand their functions and how each affects the result.
Tip: You can click on the preview window at any time in order to see
the original image. This allows an easy, rapid comparison between the
original and the filtered image.
Initial Level Adjustments
These sliders control the input values of the original image. They are
the same as using the Levels adjustment in Photoshop. Assuming your
original image already looks pretty good, these need not be changed.
However, it is often desirable to change these settings after the other
adjustments have been made. Clicking on the Show Initial Levels radio
button will show the original image before the mask is applied.
Above: Selecting Show Initial Levels displays the original, unmasked
Mask Level Adjustments
These sliders control the mask that will be used to enhance the image.
The mask is extracted from the original image based on the settings of these
sliders. Changing the sliders will change the size and shape of the mask,
altering the final image. Clicking on the Show Mask Levels radio button
will display the mask image.
Above: Clicking Show Mask Levels displays the mask that will be used to
enhance the image
The White Point slider controls the brightest part of the image. This
is the slider that will have the greatest effect on the resulting image.
The mask works by selectively allowing parts of the image to be enhanced.
The bright parts of the mask will be unchanged (preserving the bright portions
of the original image). The dark areas of the mask will be enhanced, allowing the
faint parts of the original to show through.
These sliders control the attributes of the mask, after the Mask Levels have
been applied. Click on the Show Mask Settings radio button to display the
mask image. The mask has been blurred. This is the final mask that
will be used to control the selective enhancement of the image.
Above: Mask Settings
The Blur Radius slider controls the amount of blurring applied to the mask.
This has a fairly significant effect on the final image. Clicking on Show
Final Results and changing the Blur Radius slider will show the effect. In
general, a small blur radius will result in a "flatter" image that reduces much
of the large-scale structure. A large blur radius enhances the large-scale
structure, but keep in mind that a larger blur requires more computing time.
The best option is usually to choose a number that is as low as possible but
keeps the detail you want, usually around 10-15.
Above: A Blur Radius of 5 masks much of the structure in the nebula
Above: A Blur Radius of 25 preserves the structure in the nebula
The Clipping slider changes the cutoff of the mask. Setting this slider
to 0 applies the full range of brightness of the mask. Increasing the
Clipping cuts off the darkest levels of the mask, allowing more of the faint
detail to be enhanced. Again, the default setting of 20 is a good place to
Above: Setting the Clipping to 0 applies the entire mask range
Above: Setting the Clipping to 50 cuts off much of the faintest parts
of the mask, allowing more of the faint detail of the original image to come
Typically the easiest thing to do is keep the Show Final Results radio
button checked and adjust the various sliders to get the desired results.
Above: Final Lagoon Nebula image after applying the Levelizer