RGBA is a color space representing Red (Red), Green (Green), Blue (Blue) and Alpha. It adds an alpha channel to the three color channels of red (R), green (G), and blue (B). Controls the transparency of the grid.
The alpha channel is generally used as the opacity parameter. A pixel with an alpha channel value of 0% is completely transparent (i.e. invisible), while a value of 100% means a pixel that is completely opaque (traditional digital images). Values between 0% and 100% make pixels show through the background, like through glass (translucency), an effect that simple binary transparency (transparent or opaque) cannot do .
The alpha channel value can be expressed as a percentage, as an integer, or as a real number from 0 to 255 like the RGB parameter.
For example, there is such an RGBA 4-band raster whose alpha ranges from 0 to 255, where a value of 255 means that it is completely opaque, that is, the image itself; a value of 0 means that it is completely transparent, that is, the image is invisible.
So, how to convert RGBA 4 band raster to RGB 3 band?
The following two softwares, ArcGIS and Qgis, are implemented separately!
Method 1: Use ArcGIS software
1. Load the 4-band image into ArcMap;
2. Click the right mouse button on the layer, data --> export data;
3. In the interface of exporting raster data, check Use renderer to force RGB color, and then export the raster to a new file;
4. Check the exported raster data and confirm that it has been converted into a 3-band raster;
Method 2: Use Qgis software
1. Load the RGBA 4-band raster in Qgis;
2. Find GDAL-->Raster Conversion-->Rearrange Bands in the Qgis toolbox;
3. In the rearrangement band tool, select the band to be kept;
4. Here, check the 3 bands of RGB, and keep alpha unchecked;
5. View the raster data after rearranging the bands, you can see that the alpha has been cleared and converted into a 3-band raster;
Summarize:
The above is the method of converting the RGBA 4-band raster to RGB 3-band using ArcGIS and Qgis software respectively. The process is very simple.