gvSIG-Desktop 1.1. Manual de usuario.

This assigns transparency to a raster based on the colour of its pixels. To assign this transparency, first load the cartography, then place the mouse pointer in the ToC over the raster layer you wish to modify. Right click and the contextual menu will appear.

Select the "Raster properties" option. When the dialogue box opens, select the "Transparency" tab. Only the top part of the panel corresponds to this tool. Enable the “Activate” check box and the controls that correspond to this function will be activated.

You can write the required combination of red, green and blue values in the “R”, “G” and “B” text boxes. When you have input these values, you can add them to the list with the right-facing arrow. These values will be added with an AND (&) if the “And” check box is enabled and with an OR (|) if the “Or” check box is selected.

Adding the values with an AND means that all the pixels that have the red, green and blue values we have input will become transparent. Adding the values with an OR means that all the pixels that have the red or green or blue values we have input will become transparent. If you select an entry from the list and click on the left-facing arrow, the values will appear in the text boxes and can be modified.

You can input multiple values in the list. This means that when you accept the operation all the pixels whose colour coincides with the values input in the list will be transformed.