For this time we will employ ENVI (commercial software) using mosaicking module to fill the gap of Landsat 7 ETM+
Multiple SLC-off images with the same season and year are required to utilize this method.
Individual bands of each image need to be gap-filled before creating a RGB image. For instance, in order to gap-fill Image A with Image B, a mosaic will need to be made of Band1 from Image A and Image B together. The bands can then be stacked to create the RGB image.
The steps are:
1. Open the .tif band files to be used, after envoke ENVI
2. Select Map -> Mosaicking -> Georeferenced
3. Select Import -> Import Files and Edit Properties. Click Open to choose the files you want to gap-fill; they will populate the left-hand frame.
4. Highlight one file and click OK, setting the Background See Through-Data Value to Ignore to 0. Color balancing can be done to adjust any brightness differences between the images, if needed.
5. Repeat for all files
6. Select File -> Apply, and assign an output file name and select other applicable options. Click OK.