Zusammenfassung
Enhances an image by changing properties such as brightness, contrast, and gamma through multiple stretch types based on statistics.
Diskussion
For more information about how this function works, see the Stretch raster function.
The referenced raster dataset for the raster object is temporary. To make it permanent, you can call the raster object's save method.
Syntax
Stretch (raster, stretch_type, min, max, num_stddev, statistics, dra, {min_percent}, max_percent, {gamma}, {compute_gamma}, sigmoid_strength_level)
Parameter | Erläuterung | Datentyp |
raster | The input raster. | Raster |
stretch_type [stretch_type,...] | Specify the type of stretch to apply to the image.
(Der Standardwert ist 0) | String |
min | Set the lowest pixel value for the output histogram. The output minimum (min) and output maximum (max) will set the range of values that will then be stretched. (Der Standardwert ist None) | Double |
max | Set the highest pixel value for the output histogram. The output maximum (max) and output minimum (min) will set the range of values that will then be stretched. (Der Standardwert ist None) | Double |
num_stddev | Specify the n value for the number of standard deviations to use. This method is used to emphasize how much feature values vary from the mean value; it is best when used on normally distributed data. (Der Standardwert ist None) | Double |
statistics [statistics,...] | By default, the statistics used are retrieved from the data; however, any statistic values you enter in this parameter will be used instead. Statistics are specified as: [[<min>, <max>, <mean>, <standardDeviation>] [<min>, <max>, <mean>, <standardDeviation>] [<min>, <max>, <mean>, <standardDeviation>]] (Der Standardwert ist None) | Double |
dra | Calculate statistics from only the pixels displayed on your screen. The statistics parameter is ignored when DRA is True.
(Der Standardwert ist None) | Boolean |
min_percent | Specify the percentage of the low values to exclude when the PercentClip stretch is specified. Valid values range from 0 through 99. (Der Standardwert ist None) | Double |
max_percent | Specify the percentage of the high values to exclude when the PercentClip stretch is specified. Valid values range from 0 through 99. (Der Standardwert ist None) | Double |
gamma | Specify gamma values for each band to apply to the image. For example, a three-band image would have three values, such as [<gamma1>, <gamma2>, <gamma3>]. (Der Standardwert ist None) | Double |
compute_gamma | Calculates the best gamma value to render the exported image based on an empirical model.
(Der Standardwert ist None) | Boolean |
sigmoid_strength_level | Determines how much of the sigmoidal function will be used in the stretch. A low value such as 1 will only use the middle portion of the curve, which tends to produce dull and faint colors. A high value such as 6 will use the entire curve, which tends to produce bold and sharp colors. The valid range is 1 through 6. (Der Standardwert ist None) | Integer |
Datentyp | Erläuterung |
Raster | The output stretched raster. |
Codebeispiel
Enhances an image by changing properties such as brightness, contrast, and gamma through multiple stretch types based on statistics.
import arcpy
Stretch_raster = arcpy.sa.Stretch(imagePath1, "PercentClip", None, None, None, None, True, 0.25, 0.75, None, None, None)