Images Examples


Example: How Images use Tiles from Tables

An example showing how an image is made up from data stored in a table in tiles.

Example: Create Two Images From One Table

More than one image can show data from the same table, including from the same tile field.

Example: An Image using Computed Fields in a Table

How an image can be created from tiles where the data for the tiles is taken from a field that is computed on the fly.

Example: Change the Contrast of an Image

In this example we use the Edit - Style dialog to change the contrast of an image.

Example: Use the BGR Button to Assign Channels

The BGR button in the Edit - Style dialog for images allows us to assign channels in the data to B, G and R outputs that create the displayed image, using BGR, RGB or Grayscale ordering.

Example: Assign Channels using Source

The Source control in the Style dialog for images assigns channels to display outputs such as R, G, B or A.  .  This topic shows examples of using Source and the visual results.

Example: Set Image Transparency using Alpha

The A row in the Style dialog allows us to specify what transparency we want to apply to the image, either by applying the same value for A for all pixels or by using one of the other channels to also control the A value.

Example: Autocontrast and Hill Shading Images using Style

This example shows how the Edit - Style dialog can hill shade an image using the values of pixels as heights and generating shadows as if the Sun were located at the specified azimuth and altitude.   This capability is used most frequently with raster images to give an impression of three dimensionality in cases where the values of pixels represent terrain elevations.

Example: Style Applied to an Image Server Image

Because the Edit - Style dialog simply changes the way an image is displayed and not the data, it can operate on read-only data served by various web servers such as WMS REST servers.    In this example we look at every detail of creating a data source using a WMS REST  server and then manipulating the appearance of the display with Style.  We will connect to a WMS server that provides LiDAR data in various forms, including as terrain elevation.

SQL Example: Re-tile an Image using a Different Tile Size

Starting with an image that uses a tile size of 128 x 128 pixels this SQL example creates a copy of the image using 500 x 500 pixel tiles.