HDR history
As a precursor, let me reiterate, these blogs are for intelligent people with a university background and courses in mathematics, engineering, physics and other of the hard sciences.
The first HDR image was the result of the independent work of Prof. Paul Debevec, U.C., and Gregory Ward Larson, JPL.
Prof. Debevec developed an algorithm to composite several images into one. His work was published in a research paper still available online. In the back of the paper is a Matlab script of the algorithm. Matlab is published by Mathworks, Inc, and is the foremost mathematics laboratory, Matlab is widely used by scientists and professionals in a science related field.
One of the unknown benefits in HDR is the ability two construct an HDR image with only two exposures (images) if the same film is used for several images. Prof. Debevec derived an additional algorithm for determining the film character and using that data to reduce the number of images needed for a HDRI (High Dynamic Range Image) to two, widely spaced in shutter speed and a constant aperture.
The aperture remains constant since the depth of field changes with aperature. The focus changes and the range and extent of blurring changes.
A program was developed and made freely available for non-commercial use. That was HDRShop, a take off on the name "Photoshop'. The software was and is research oriented, therefore, very sophisticated. Amateur digital photographers can use the s/w (software) readily, but there is much more available to those with a knowledge of the physics and mathematics of light and photography.
HDRShop can take a series of digitized or digital images and construct a HDR image, making automatic adjustments and categorizing the images by exposure level without user interaction.
The images can be used to construct a set of characterization curves that make construction of future images from the same camera, simpler by using only two images instead of the initial four-to-seven.
The standard compressor associated with HDRShop is Eric Reinhardt's 'Tonemap', an embodiment of Alfred Eisenstadt and company's 'Zone Method' still in use today. Tonemap is the most popular and unarguably, the best general purpose compressor available. The term 'Tonemap' is generic and refers to one of several methods in use.
Gregory Ward Larson developed a software suite named 'Radiance'. Radiance is an architectural daylight rendering engine. Give the software some data and an image portraying realistic effects of daylight will be created an stored. There are different kinds of image formats. Most are for conventional computer displays and therefore of limited use. Radiance comes equipped with what was then, a new concept. An image containing more information than a display monitor could place on the screen. The computer image created by Radiance was the closest thing yet to portraying real light in a scene. Greg Larson developed an image format (way of storing image data) for the expanded images. The format was composed of 32-bit floating point numbers where existing images were composed of integers. He gave the new format the extension '.hdr', as in 'living_room.hdr'. While he adapted other formats such as .tiff and .png to 32-bit floating point storage, the .hdr format is that most clodely associated with the technology.
This was in the mid-90's. As time passed, the combination became synonymous with HDR.
The technology developed over the years but the algorithms from Debevec and Larson are the foundation and have changed little. The compressor, however, has 'evolved' with dozens of approaches implemented in software. Each one accompanied by a research publication explaining the theory behind each.
Many programs have copied their work but have improved it little. Most elaborate the methods with conveniences, 'bells and whistles' if you will.
Even Adobe implemented a version in their Photoshop program.
HDR imaging is quite common now and is widely used, and abused, in the phtography and movie industry.
The first HDR image was the result of the independent work of Prof. Paul Debevec, U.C., and Gregory Ward Larson, JPL.
Prof. Debevec developed an algorithm to composite several images into one. His work was published in a research paper still available online. In the back of the paper is a Matlab script of the algorithm. Matlab is published by Mathworks, Inc, and is the foremost mathematics laboratory, Matlab is widely used by scientists and professionals in a science related field.
One of the unknown benefits in HDR is the ability two construct an HDR image with only two exposures (images) if the same film is used for several images. Prof. Debevec derived an additional algorithm for determining the film character and using that data to reduce the number of images needed for a HDRI (High Dynamic Range Image) to two, widely spaced in shutter speed and a constant aperture.
The aperture remains constant since the depth of field changes with aperature. The focus changes and the range and extent of blurring changes.
A program was developed and made freely available for non-commercial use. That was HDRShop, a take off on the name "Photoshop'. The software was and is research oriented, therefore, very sophisticated. Amateur digital photographers can use the s/w (software) readily, but there is much more available to those with a knowledge of the physics and mathematics of light and photography.
HDRShop can take a series of digitized or digital images and construct a HDR image, making automatic adjustments and categorizing the images by exposure level without user interaction.
The images can be used to construct a set of characterization curves that make construction of future images from the same camera, simpler by using only two images instead of the initial four-to-seven.
The standard compressor associated with HDRShop is Eric Reinhardt's 'Tonemap', an embodiment of Alfred Eisenstadt and company's 'Zone Method' still in use today. Tonemap is the most popular and unarguably, the best general purpose compressor available. The term 'Tonemap' is generic and refers to one of several methods in use.
Gregory Ward Larson developed a software suite named 'Radiance'. Radiance is an architectural daylight rendering engine. Give the software some data and an image portraying realistic effects of daylight will be created an stored. There are different kinds of image formats. Most are for conventional computer displays and therefore of limited use. Radiance comes equipped with what was then, a new concept. An image containing more information than a display monitor could place on the screen. The computer image created by Radiance was the closest thing yet to portraying real light in a scene. Greg Larson developed an image format (way of storing image data) for the expanded images. The format was composed of 32-bit floating point numbers where existing images were composed of integers. He gave the new format the extension '.hdr', as in 'living_room.hdr'. While he adapted other formats such as .tiff and .png to 32-bit floating point storage, the .hdr format is that most clodely associated with the technology.
This was in the mid-90's. As time passed, the combination became synonymous with HDR.
The technology developed over the years but the algorithms from Debevec and Larson are the foundation and have changed little. The compressor, however, has 'evolved' with dozens of approaches implemented in software. Each one accompanied by a research publication explaining the theory behind each.
Many programs have copied their work but have improved it little. Most elaborate the methods with conveniences, 'bells and whistles' if you will.
Even Adobe implemented a version in their Photoshop program.
HDR imaging is quite common now and is widely used, and abused, in the phtography and movie industry.
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