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Due to the wide range of image enhancement features available in XVa3, it is not always straight forward to determine what enhancement should be used when. The goal of this document is to help illustrate what several of the more popular enhancements do to image quality.
XVa3?s on-line help contains detailed information
on how to apply the various enhancements presented in this document.
The term ?brightness/contrast enhancement? is a term that is applied to a variety of image improvement operations. In general, brightness/contrast enhancement changes the brightness and the contrast of an image in order to try to improve the overall dynamic appearance of an image.
The exact brightness/contrast enhancement
required will vary from image to image.
To illustrate the effect of each of the presented brightness/contrast enhancements, the following images will be used.
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Enhancement |
Image Result |
Description |
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Real-Time B/C |
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The real-time B/C control available in XVa3 can be used to quickly modify
the appearance of an image. |
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Auto B/C |
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The Auto Brightness/Contrast feature automatically tries to determine
the optimal brightness/contrast settings for the image. |
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Equalizing |
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Equalizing is a non-linear approach to altering the brightness/contrast of an image. Note that equalizing does not always produce a usable image. Typically, this enhancement is used when dealing with very low contrast images. |
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Gamma Correction |
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Gamma correction is a very versatile tool when dealing with images that are captured by video hardware. Usually, gamma correction is used in combination with one of the other B/C enhancement tools to dramatically improve the overall appearance of an image. |
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Levels |
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Leveling adjusts the brightness/contrast of an image by shifting the image's histogram in order to increase the contrast range of the image. You have the ability to specify the level adjustment value manually, select the average value of the image or select the median intensity of the image. |
Due to the fact that most images have some degree of blurriness (from focus problems or inherent limitations in the image taking process), XVa3 offers two forms of image sharpening: Sharpening and Laplace Edge Enhancement. Each sharpening method utilizes a different approach to sharpening an image, but both methods can compensate for the blurriness in an image.
Panoral and ceph images will automatically
contain a certain degree of blurriness due to the manner in which the
images are taken.
A panoral image with sharpening applied to the image.
A ceph image with sharpening applied to the image.
From time to time, an enhancement operation may make an image appear too grainy (it enhances problems in the image from when it was taken or developed). Typically graininess can be attributed to the increased contrast between adjacent pixels in an image. The smooth operation permits you to reduce the effect of the graininess in the image.
Noise in an image can consist of any of a number of things such as dust, scratches or image static. XVa3 provides a variety of noise reduction features. The primary difference between the noise reduction operations is what each considers to be noise. Usually, median noise reduction results in the best images.
