Setting Image Layer Properties

After selecting an image layer in the Layer Manager, the Layer Properties panel will display image parameter options, including brightness, contrast, transparent color, interpolation method, display method, etc.

The system supports selecting multiple image layers simultaneously for batch property settings. However, when the selected layers contain both single-band and multi-band images, the parameters in the Display Method group cannot be set uniformly.

Display Control

The display control group organizes general parameters for layer properties. For details, please refer to Setting Layer Common Properties.

No Value

  • No Value: Refers to the pixel value in the image data that has no practical meaning. You can directly input a pixel value (or click the pick button on the right to pick from the image layer) to specify it as a No Value.
    • For a single-band image layer, directly input the pixel value.
    • For a multi-band image layer, input an RGB color value.
  • No Value Transparent: Used to set the display color for No Value areas. Checking this box means setting the No Value area to be transparent.
  • No Value Color: This option becomes available after unchecking "No Value Transparent." Once selected, choose a color value from the drop-down button on the right to use as the display color for No Value areas.
Note:

The No Value on the image dataset attribute panel is represented by an RGB decimal integer value. However, the No Value on the image dataset layer properties panel is associated with the vertex color. When the vertex color is RGB, e.g., the No Value is 96555, it will be displayed as (1,21,43) in the Layer Properties panel.

Background Value

Sets the specified pixel value as the background value to change the display color of the area covered by this background value.

  • Background Value: You can directly input a numerical value as the background value. Alternatively, use the pick button on the right to select a pixel value from the map as the background value.
    • For a single-band image layer, directly input the pixel value.
    • For a multi-band image layer, input an RGB color value.
  • Background Transparent: Checking this box means the area covered by the background value is set to be transparent. After unchecking, you can select a color value from the drop-down menu on the right as the background color.

Transparent Color

You can set the area covered by a specified pixel value in the image layer to be transparent.

  • Transparent Color: After checking this box, use the pick button on the right to select a pixel value from the map. The area covered by this pixel value will automatically be set to transparent.
  • Transparent Color Tolerance: Sets the tolerance range for the transparent color. If the original color setting is (r, g, b) and the tolerance setting is a, then the range requiring transparent display is from (r-a, g-a, b-a) to (r+a, g+a, b+a). The default value is 0, the valid range is [0, 255], and it must be an integer.

Brightness

Used to adjust the brightness of the image layer.

You can directly input the brightness value or use the spinner button on the right to set it.

Contrast

Used to adjust the contrast of the image layer.

You can directly input the contrast value or use the spinner button on the right to set it.

Interpolation Method

When zooming in or out to browse the image layer, the original image needs to be mapped to a larger or smaller set of pixels for quick browsing. Different interpolation methods determine the quality of the image display.

  • Nearest Neighbor: A relatively simple image interpolation method with fast processing speed, but the image display effect is the poorest.
  • Low Quality: This method performs pre-filtering to ensure high-quality shrinking, but the quality of the zoomed-in image display after interpolation is not good.
  • High Quality: Provides higher image display quality during zooming, but the output image time is longer.
  • High Quality Bilinear: Performs pre-filtering using the specified high-quality bilinear interpolation method to ensure high-quality display effects for scaled images.
  • High Quality Bi-cubic: Performs pre-filtering using the specified high-quality bi-cubic method to ensure the highest quality display effects for scaled images. This method yields the highest output image display quality.

Display Method

Display methods differ based on the number of bands in the image data, categorized into single-band and multi-band images. These are introduced separately below. Additionally, modifying the display method is not supported for image data with a bit depth of 32 or 24.

Single-band Image

  • Default Display: Does not perform stretch display on the image. If the image data has a color table, it is displayed using the color table; if not, it is displayed using grayscale values.
  • Stretch Display: Performs stretch display on the image based on a color scheme.
    • Color Scheme: Checking this box means stretching is performed based on the specified color scheme. If unchecked, stretching uses the image's color table (or grayscale values if no color table exists). You can select a predefined color scheme from the color drop-down menu on the right for display, or customize the display color using the edit button on the far right. Changing the color scheme is only supported for image data with a pixel format of 8-bit or 16-bit.
    • Stretch Method: Default is Percent Clip. For more method introductions, please refer to Image Stretching Methods.
  • Color Table Display: Displays the image data using the specified color scheme. You can select a predefined color scheme from the color drop-down menu on the right for display, or customize the display color using the edit button on the far right. Changing the color scheme is only supported for image data with a pixel format of 8-bit or 16-bit.
  • Grid Function Display: Displays the image according to the specified raster function, providing two methods: 3D Halo Map and Orthographic 3D Image. For more method introductions, please refer to Setting Raster Layer Properties.

Multi-band Image

  • Combination Display: Displays the image multiband by stretching it according to the specified vertex color.
    • Color Model: Used to set the color display mode for the image data. RGB is used by default. Descriptions of the color models are as follows:
      Color Model Description
      RGB

      R, G, B are abbreviations for Red, Green, and Blue, respectively. It mixes various colors by adjusting the values of these three primary colors.

      Primarily applied in display systems.
      CMYK

      Available when the stretch method is not Percent Clip.

      C, M, Y, K stand for Cyan, Magenta, Yellow, and Black, respectively. It mixes various color pigments by adjusting the concentration of the three basic colors: cyan, magenta, and yellow, and uses black to adjust brightness and purity.

      Primarily applied in printing systems.
      RGBA

      Available when the stretch method is not Percent Clip.

      R, G, B are abbreviations for Red, Green, and Blue, respectively, while A controls transparency.

      Primarily applied in display systems.
      CMY

      Available when the stretch method is not Percent Clip.

      C, M, Y stand for Cyan, Magenta, and Yellow, respectively. It mixes various color pigments by adjusting the concentration of these three basic colors.

      Primarily applied in printing systems.
      YIQ

      Available when the stretch method is not Percent Clip.

      Primarily applied in the North American television system (NTSC).
      YUV

      Available when the stretch method is not Percent Clip.

      Primarily applied in the European television system (PAL).
      YCC

      Available when the stretch method is not Percent Clip.

      Primarily applied in the JPEG image format.
    • Stretch Method: Default is Percent Clip. For more method introductions, please refer to Image Stretching Methods.
  • Single Band Stretch Display: Performs stretch display on a specified band based on a color scheme.
    • Bands: Specifies the band to be displayed.
    • Color Scheme: Checking this box allows you to select a predefined color scheme from the color drop-down menu on the right for display. You can also customize the display color using the edit button on the far right. Changing the color scheme is only supported for image data with a pixel format of 8-bit or 16-bit.
    • Stretch Method: Default is Percent Clip. For more method introductions, please refer to Image Stretching Methods.
  • Single Band Color Display: Displays the specified band based on a color scheme.
    • Bands: Specifies the band to be displayed.
    • Color Scheme: Select a predefined color scheme from the color drop-down menu on the right for display. You can also customize the display color using the edit button on the far right. Changing the color scheme is only supported for image data with a pixel format of 8-bit or 16-bit.
  • Single Band Grid Function Display: Displays single-band data using the specified raster function, providing two methods: 3D Halo Map and Orthographic 3D Image. For more method introductions, please refer to Setting Raster Layer Properties.

Gamma

The Gamma parameter enables non-linear brightness and contrast adjustment of the image, thereby enhancing image display details and improving the display quality of image data. The Gamma parameter value ranges from [0,10], with a numerical precision of two decimal places.

Setting the Gamma parameter is not supported when the display method is Single Band Grid Function Display or Grid Function Display. The implications of the Gamma value are as follows:

  • When the Gamma value equals 1, no gamma correction is applied to the image.

  • When the Gamma value is greater than 1, the contrast in the dark areas of the image increases, making details more prominent, but details in bright areas may be somewhat lost, and the overall image becomes brighter.

  • When the Gamma value is less than 1, the contrast in the bright areas of the image increases, making details more prominent, but details in dark areas may be somewhat lost, and the overall image becomes darker.

Figure: Gamma=1 Figure: Gamma=2
Figure: Gamma=1 Figure: Gamma=0.4


Displays the Orthorectified Image

If the dataset associated with the layer contains RPC information, this checkbox can be enabled. When checked, it displays the image after orthorectification based on elevation data; when unchecked, it displays the uncorrected image.

After checking, the following three setting methods are provided in the elevation value input box and the drop-down menu on the right:

  • Fixed Value: Displays the elevation value from the remote sensing image file by default. You can directly edit other values in the text input box.
  • SRTM V4: Uses elevation information from the remote sensing resource package. This option is available after performing Image Environment Deployment.
  • Custom: Loads elevation information by specifying DEM data. Supports four formats: Tiff/GeoTIFF, Erdas Image, PCIDSK, and ArcInfoGrid. Among these, ArcInfoGrid format data can only be obtained by clicking the Add Folder button.

Related Topics

Setting Layer Common Properties

Setting Vector Layer Properties

Setting Raster Layer Properties