Image Stretching

Feature Description

During the acquisition of remote sensing imagery, factors such as sensor characteristics and atmospheric conditions often result in an unfavorable brightness dynamic range distribution of source data, causing insufficient contrast and difficulty in distinguishing details during direct display. Image stretching, through mathematically transforming pixel values, mainly achieves the following two core purposes:

  • Optimize visual effects: By adjusting the distribution and contrast of pixel values, the spectral or texture differences of different ground objects are visually enhanced.
  • Realize bit depth conversion: For example, converting high bit depth data (e.g., 16-bit) to a lower bit depth format more suitable for storage, transmission, or display (e.g., 8-bit), while preserving key information and minimizing pixel loss through stretching methods.

Parameter Description

Parameter Name Parameter Interpretation Parameter Type

Image File List

Manage image files to be stretched.

  • Add Image: Set the image to be stretched. Supports *.tiff, *.tif, *.img, *.pix formats.
    • Add File: Select one or more image files from a local directory.
    • Add Folder: Select a folder from a local directory, and all images in this folder and its subfolders will be automatically obtained.
    • Add List: Select a manifest file (*.csv) from a local directory, and images will be obtained based on the image name and path information in the manifest file.
    • Add Mosaic Data: Select a mosaic dataset from the current workspace.
  • Select All: Select all files in the list.
  • Select Reverse: Reverse the selection status of all files in the list.
  • Delete: Remove the selected records from the list.
 DatasetImage
Output Directory Set the storage path for the result image. String
File Type Set the storage type of the result image. Provides four options: Not Set, Tiff/GeoTIFF, Erdas Image, and PCIDSK, with the default being Tiff/GeoTIFF. When Not Set is selected, the original storage type of the image is used for output. FileType
Compression Method Set the compression method for the output image. Only available when the output format is Tiff/GeoTIFF. Default is NONE. CompressMethod
Pixel Format Set the pixel bit depth of the processed output channel. Available options include:
  • 8-bit Unsigned (default): Unsigned 8-bit integer.
  • 16-bit Unsigned: Unsigned 16-bit integer.
  • 16-bit: 16-bit signed integer.
  • 32-bit: 32-bit signed integer. This option is not available when the file type is PCIDSK.
 PixelFormat
Stretch Method

Set the method for image stretching. Default isPercent Clip, and also provides Gaussian, Gamalashin, Histogram Equalization, and Logarithmic Stretch. For more method details, please refer to Image Stretching Methods.

 ImageStretchingType
Minimum Value Available when the Stretch Method is Percent Clip. Default value is 1. Double
Maximum Value Available when the Stretch Method is Percent Clip. Default value is 99. Double
Gaussian Standard Deviation Coefficient Available when the Stretch Method is Gaussian. Default value is 3. Integer
Gamalashin Coefficient Available when the Stretch Method is Gamalashin. Default value is 0.5. Double
No Data Value Set the value for the no-data area of the image. Default is  0. Double
Index Set the index to export. The correspondence is between sequence number and band value.
Boolean

Output Result

Output the result image data to a local folder.