In computer graphics and photography, high dynamic range imaging (HDRI) is a set of techniques that allow a far greater dynamic range of exposures (i.e. a large range of values between light and dark areas) than normal digital imaging techniques.
The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to the deepest shadows.
HDRI was originally developed for use with purely computer-generated images. Later, methods were developed to produce a high dynamic range image from a set of photos taken with a range of exposures. With the rising popularity of digital cameras and easy to use desktop software, the term "HDR" is now popularly used[1] to refer to the process of tone mapping together with bracketed exposures of normal digital images, giving the end result a high, often exaggerated dynamic range. This composite technique is different from, and generally of lower quality than, the production of an image from a single exposure of a sensor that has a native high dynamic range. Tone mapping is also used to display HDR images on devices with a low native dynamic range, such as a computer screen.
Recently, CMOS image sensor producers have begun to release sensors with HDR up to 110 dB for security cameras.[2]
PHOTOMATIX
Photomatix Pro is a stand-alone program that runs on Mac OS X and Windows 98/Me/2000/XP/Vista. The Tone Mapping tool is also available separately as a plugin compatible with Photoshop CS2.
One license for Photomatix Pro costs US$99 or €75. One license for the Tone Mapping Plug-In costs US$69 or €55.
The benefits of using Photomatix Pro include:
› Saving on lighting equipment
Given that most digital cameras can auto-bracket at different exposures, you do not need to acquire expensive lighting equipment -and carry it- when shooting high contrast scenes. Just enable Auto Exposure Bracketing, and let Photomatix merge your photos into an image with extended dynamic range.
› Saving time in post-processing
Photomatix Pro is designed for productivity -- automatic blending, unlimited stacking, easy comparison of results and batch processing save hours of masking and layers work in image editing programs.
› Taking advantage of your 32-bit images
Have you created a 32-bit HDR image in Photoshop CS2 and could not get a good HDR conversion? The Photomatix Tone Mapping tool may help. See how it compares to Photoshop CS2 HDR conversion.
› Great pictures on cloudy days
Shadowless hazy sunlight or an overcast sky usually results in dull-looking photographs. The tone mapping tool of Photomatix Pro can turn them into great-looking images. Check this image as example.
› Noise reduction
The Exposure Blending functions of Photomatix Pro merge any number of bracketed photos -- this process is equivalent to image stacking, which tends to reduce noise in the resulting image.
› Well exposed panoramas
A panoramic scene is almost always a high contrast scene -- you can't limit your view to areas with the same brightness when shooting a 360° panorama. By taking views under several exposures and processing them in Photomatix Pro, you can create a panorama that will show details in both the dark and bright areas of the scene.
this is my sample picture of HDRi.
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