An image service can be displayed and rendered in many ways based on the type of metadata it contains and how the service was prepared. Based on the quality of the image and your workflow task, you may want to improve the appearance of your imagery. The display tools allow you to apply common display settings to your imagery and change the order of your imagery to gain the most value out of each pixel.
Image Display tool
The Image Display tool allows you to use renderers, change band combinations, and apply common settings such as dynamic range adjustment (DRA) and gamma to your imagery.
Apply a renderer
Image services can be displayed, or rendered, in many ways. Rendering is the process of displaying your data. Some image services have predefined templates associated with them. If an image service contains predefined renderers, they are available in the renderer drop-down menu with the top-most renderer selected as the default. If the image service does not contain a predefined renderer, the renderer drop-down menu is set to User Defined Renderer.
To change the image service renderer, complete the following steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Image Display.
- In the Renderer drop-down list, choose a renderer.
- Predefined renderer—Any renderer in the list other than User Defined Renderer. When you choose a predefined renderer, no additional user-defined settings can be set.
- User defined renderer—Available for all image services. When you choose a user-defined renderer, you can apply user-defined settings such as DRA and gamma.
Once you choose a renderer, it is automatically applied to the image service.
Transparency
Changing the transparency, or opacity, of the image layer allows you to see more, or less, of the underlying basemap. The transparency of the image layer can be adjusted from 0 percent to 100 percent. The more transparent the layer is, the less visible it appears on the map.
To change the Image Layer Transparency, follow these steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Image Display.
- Use the Transparency slider to select the transparency level.
The imagery will dynamically change when transparency is applied.
Compression
There are tradeoffs between performance and image quality because they are inversely related. Higher-quality images will be larger files and will affect performance speed. Performance is also dependent on your connection speed.
To change the Image Layer Compression, follow these steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Image Display.
- Use the Compression slider to select the compression level.
- Performance - Compresses into a JPEG format at 50 percent quality.
- Balance - Compresses into a PNG32 format when there are NoData pixels present in the current view and compresses into a JPEG format at 75 percent quality when there are no transparent pixels.
- Quality - Compresses into a PNG32 format when there are NoData pixels present in the current view and creates a JPEG compression at 95 percent quality when there are no transparent pixels.
The imagery will dynamically change when compression is applied.
Apply DRA settings
Dynamic range adjustment enhances the image by dynamically stretching the image based only on the pixel values in the display, not all pixels in the service.
To apply DRA, complete the following steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Image Display.
- In the Available Renderers drop-down list, choose User Defined.
- Under Quick Enhancements, click DRA. You will notice a change in the pixels of your image in the current view.
Note:
DRA requires a stretch type to be applied. When DRA is toggled on, a minimum and maximum stretch type is automatically applied to the imagery service. This stretch type can be changed using the Enhancements tool.
Apply gamma settings
Gamma enhances an image by dynamically stretching the middle values in an image while keeping the extreme high and low values constant.
To apply gamma, complete the following steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Image Display.
- In the Available Renderers drop-down list, choose User Defined.
- Under Quick Enhancements, click Gamma. You will notice a change in the pixels of your image in the current view.
Apply band combinations
The band combination setting allows you to specify which bands are displayed using the red, green, and blue color composite scheme. Using different color combinations, you can display your imagery with various color effects. You can use natural color (red, green, and blue), which displays the layer as you would normally see it. Other color combinations can highlight vegetation, urban areas, water, and other features.
The band combination setting is only available when User Defined Renderer is chosen and the image service is a multiband service.
To change the multi-spectral band combinations that display, complete the following steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Image Display.
- In the Renderer drop-down list, choose User Defined Renderer.
- For the Set Custom RGB Renderer, click the band selection drop-down
arrow and choose band numbers for red,
green, and blue.
Note:
If the image service is a single-band service, this option will not be visible.
- Click the Apply Bands button to apply the RGB composite.
- Optionally click the Reset Bands button to return to the default combination.
Image Order tool
Image services contain one or more images that are mosaicked on-the-fly and behave like a single image when you browse the service. The image order tool can help determine the image order and how to resolve overlapping areas. This specifically becomes useful when there are multiple images over the same area.
To access the image order tool, complete the following steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Image Order Tool.
- Update the display priority of your choice using the following options. Only one option can be applied at a time.
- By Attribute - orders imagery based on values of a numeric or date attribute. The reverse order of the selected attribute can also be set on this option.
- Center - orders image centers closest in distance to the center of the screen display on top.
- Nadir - images with their nadir point closest in distance to the center of the screen are displayed on top.
- Northwest - orders images based on the center of each image's distance to the northwest corner of the collection of all images in the layer.
The Map Focus Panel will dynamically change when the order changes.
Note:
The tool is disabled when the view is set to display a specific set of selected images from an imagery layer.
- Click Reset to Default Order to revert to the original image order.
Enhancements tool
The Enhancements tool helps improve the quality of the image. The stretch enhancements changes an image's brightness, contrast, and gamma through stretch types. The filter enhancements help filter the pixels in the image so it can be used to sharpen, blur, or detect edges within an image. The enhancements tools are disabled when the renderer in the Image Display Tool is set to a non-User Defined renderer.
Change resampling
Resampling is the process of interpolating the pixel values while transforming your raster dataset. This is used when the input and output do not line up exactly, when the pixel size changes, when the data is shifted, or a combination of these. To change resampling, click the dropdown menu to choose from:
- Bilinear - Determines the new value of a cell based on a weighted distance average of the four nearest input cell centers. It is useful for continuous data.
- Cubic Convolution - Determines the new value of a cell based on fitting a smooth curve through the 16 nearest input cell centers. It is appropriate for continuous data, but may result in the output raster containing values outside the range of the input raster.
- Majority - Determines the new value of the cell based on the most popular values within the filter window. It is mainly used with discrete data.
- Nearest Neighbor - Fastest interpolation method and primarily used for discrete data. It will not change the values of the cells.
Stretch
To apply stretch enhancements to your imagery, complete the following steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Enhancements.
- Under Apply Functions, click the Stretch tab, and choose from the list of options:
- No Stretch
- Histogram Equalization
- Min Max
- Percent Clip
- Standard Deviation
The imagery will dynamically change when a stretch method is applied.
- To clear any stretch enhancements applied, click the Reset button.
Note:
The Stretch and Filter functions cannot be applied at the same time. Any Stretch enhancements applied in the Enhancements tool will be directly reflected in the Image Display Tool.
Filters
To apply filter enhancements to your imagery, complete the following steps:
- Click the Tools menu in the imagery exploitation canvas.
- In the Display Tools list, click Enhancements.
- Under Apply Functions, click the Filter tab and choose the filter you want applied to your images.
- To clear any filter enhancements, click Reset.
Note:
The Stretch and Filter functions cannot be applied at the same time.