Image Processing Reference
In-Depth Information
Let's have a look at the hardware prerequisites before we start on the
necessary software.
There are special high dynamic range imaging (HDRI) cameras available,
but so far they are bound and controlled by a computer. They are also very
expensive. Nevertheless, there are many digital cameras (compact as well as
digital single-lens reflex, or DSLR) that have an (auto) exposure bracketing
feature included.
As to the rendering and output on the monitor and printer, neither
the graphics board nor the monitor or printer is able to render the original
dynamic range of HDR images. These are known as low dynamic range (LDR)
media. Another step is necessary to maintain the richness in detail of an HDR
image when you're rendering and editing it. The image needs to undergo a
process called tone mapping . The overall contrast of the image is reduced to
facilitate the display on devices with lower dynamic range. The photographer,
therefore, chooses what details can be kept and which are dispensed. A loss
of detail is to be expected, yet the resulting file remains with the desired
brightness and color contrasts and can be viewed and saved. The actual result
is an LDR image, which is developed after and from the original HDR image
with the help of the tone mapping technique. The HDR image itself can be
saved separately.
3.15.2 HDR Software
To create HDR images, you need special software. GIMP can be used to edit
only images with 8 bits per channel, but there is a Python plug-in that will
create HDR images with the help of GIMP. More information and the download
can be found at
The open-source community offers Cinepaint (previously known as
FilmGIMP or Glasgow) for Linux, Windows, and Mac OS for creating HDR
images (as mentioned in section 1.5.1). You can find the download and
tutorials at the following locations:
For Linux and Mac OS, you can also use Krita (also mentioned in section
1.5.1). The program supports the OpenEXR file format. It can be used to edit
HDR images in this format. However, the programmers are still working on a
range of functions to create HDR images. Information on Krita can be found
on the following locations:
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