Anyone
who has ever used a camera either digital or film has experienced exposure
issues of one sort or another, such as over or under exposure. This is one
of the most common problems any photographer will go through, and since
some moments in life retaking the photo just isn't the option, you
shouldn't be stuck with poorly exposed images. One of Artizen's strong
points is it's ability to handle exposure issues in many different ways in
many different color spaces, whether it be a JPEG, a Digital Camera RAW
file or even a High Dynamic Range image. Here we will focus on dealing
with JPEG's, Digital Camera RAW files and Tone Mapped HDR files which are
usually either 8 or 16bit images.
In Artizen all of the exposure tools have been put together into what
we consider a power filter, the Exposure Filter. This is easily accessible
by simply selecting the Exposure Filter located under the menu option
Modify | Exposure...
Once loaded you will notice that you have 8
controllable options with the first 4 options focused on how the overall
exposure is adjusted and the second grouping of 4 control how the
distribution of light is handled or what is referred to as the Contrast of
the a photo.
Brightness - This option is a the most common of
Exposure tools and is found in most graphic applications. It simply
adjusts the overall brightness of a photo by uniformly adjusting the pixel
values in your image.
Reflection - Since many High Dynamic Range
photographers use Mirror Balls to produce their images, some data is lost
due to reflection. This is cause no surface is 100% reflective and so this
option enables photographers to correct this data loss.
Shift - This option shift all the luminosity values
equally across the histogram.
Contrast - This option controls how light is
distributed across a given range either 8 or 16bit color space. This
depends on which type of photo you are work with a RAW or JPEG.
Highlights - Just like Contrast this option
controls the distribution of light but only across the Highlight range.
Sometimes adjusting the Contrast option will affect parts of the photo you
don't want affected, and that this option enables you to set a different
contrast correction to just the Highlights without ever affecting the
Shadows.
Shadows - Just like Contrast this option controls
the distribution of light but only across the Shadows range. Sometimes
adjusting the Contrast option will affect parts of the photo you don't
want affected, and that this option enables you to set a different
contrast correction to just the Shadows without ever affecting the
Highlights.
White Point - This option sets all values above it
equal to white. The lower the value the brighter the image becomes.
Black Point - This option sets all values below it
equal to absolute black. The higher the value the darker the image
becomes.
Gamma - This option is the standard way of
adjusting contrast in both displays and cameras but in a non linear
method. Most Displays have a gamma level of 2.2, but since there are
differences between gamma correction from device to device it is important
to be able to adjust this option.