my AOI requires two scene of satellite image but when I try to mosaic the images using ERDAS imagine, the color of the edge is seen forming black line after mosaic! so please how can I remove the image edge color?
Do you mean the outside edge of the combined image, or along the join?
Near Black tool in QGIS would help.
Or if the colour is not present anywhere else, you can
Reclassify that pixel type to NoData or whatever class you want.
My approach would be to draw a border shape around your AOI, save it to a shapefile and the use GDAL's crop_to_cutline command to crop the image to those borders. After performing this operation on both of your sat. images, you should be fine to mosaic them!
Hope it helped!