histogram


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histogram

[′his·tə‚gram]
(statistics)
A graphical representation of a distribution function by means of rectangles whose widths represent intervals into which the range of observed values is divided and whose heights represent the number of observations occurring in each interval.
Histogramclick for a larger image
Fig. 13 Histogram. A diagrammatic representation (f=frequency) of a frequency distribution, consisting of contiguous rectangles, in which the width of each rectangle is proportional to the class interval under consideration and the area of each rectangle is proportional to the associated frequency.

histogram

a diagrammatic representation of a FREQUENCY DISTRIBUTION, consisting of contiguous rectangles displaying interval-level data (see CRITERIA AND LEVELS OF MEASUREMENT) grouped into categories. In a histogram the width of the rectangle is proportional to the class interval under consideration, and the height is the associated frequency. The area of each bar is then proportional to the frequencies for each class interval (see Fig. 13). A histogram differs from a BAR CHART in that it is the areas of the rectangles which represent the relative frequencies.

Histogram

 

a column diagram, a type of graphical representation of the statistical distributions of some quantities in quantitative terms. A histogram represents a set of contiguous rectangles constructed on a straight line. The area of each rectangle is proportional to the frequency with which the given quantity is found in the set being studied. For instance, let the measurement of the trunk diameters of 624 pine trees produce the following results:

Diameter (cm)...............14-2222-3030-3838-62
No. of trunks57232212123

The limits of the groups into which the trunks are divided by diameter are plotted along the horizontal axis, and on the segment corresponding to each group, a rectangle having an area proportional to the number of trunks within the given group is constructed as if on a foundation (Figure 1).

The granulometric composition of rocks is often depicted in the form of a histogram. In this case the percent content of the obtained groups of particles of so-called fractions is plotted on the vertical axis and the logarithms of their limiting

Figure 1

size are plotted on the horizontal axis (Figure 2). The use of logarithms is necessitated by the fact that in granulometric analysis, the particles are subdivided into fractions whose size diminishes in a geometric progression. Histograms are

Figure 2

occasionally constructed on arbitrarily chosen equal segments, regardless of the difference in the limiting size of the fractions. Then the heights of the columns are proportional to the content of the fraction sizes.

histogram

A bar graph that uses the width of the bars to represent the various classes and the height of the bars to represent their relative frequencies.

Camera Histograms
Digital camera histograms show the image's overall exposure. Using 256 vertical bars to represent brightness levels from 0 to 255, the leftmost bar is the darkest pixel level (0), and the rightmost bar is the lightest (255). The height of the bars represents the total number of pixels at that brightness level.

What is of most interest to the photographer is how the bars spread horizontally from left to right. For example, if there are no bars on the left, there are no black pixels in the image.


Light Pixels
Histograms appear on the same LCD screen used to preview the image. In this daylight example, there is an absence of dark shadows because the histogram shows no pixels on the left side (dark side).







Dark Pixels
In this example, the camera was pointed into a totally dark room, and the bars are confined entirely to the leftmost side (dark side).
References in periodicals archive ?
A popular general-purpose method of image enhancement is histogram equalization.
While our formulation is quite different due to our focus on the residual, it can nevertheless be related on a conceptual level with numerous methods that have been proposed for image contrast enhancement or segmentation problems which are based on the modification of the histogram of an input image toward a target histogram.
This will provide data ranges for our histogram and retain a link to the data.
that separates SEL's of light and heavy vehicle passing by from cumulative function of obtained representative histogram and measured proportion of heavy vehicle [H.
As previously mentioned, some analyzers only have one histogram per module to differentiate cellular elements; however, newer analyzers have the ability to access data from multiple histograms.
Using the estimated delays and creating their histogram, we shall be able to detect two histogram peaks, [[delta].
The MLP structure was trained with sampled histogram values (each 5th value was sampled) with different amount of Motion Blur (3, 6 and 9 Pix MB) and different illuminations Fig.
Feature database is created form the image database using Edge Histogram descriptor (EHD) and colour features.
Examples are Recursive Mean-Separate Histogram Equalization (RMSHE) [7], Dynamic Histogram Equalization (DHE) [8], Weighted Thresholded Histogram Equalization (WTHE) [9] and Scalable Global Histogram Equalization with Selective Enhancement (SGHESE) [10].
The cross distance formula considers the cross-correlation between histogram bins based on the perceptual similarity of the colors represented by the bins.
3D], determined by screening, makes it possible to reformulate the histogram [g.