Some images in the open when GIMP，"The colors into Alpha (Transparent)"The option is not available，Before did not know how to solve，Finally found a solution today。In accordance with the users point of view in the official return of issue，The reason for this layer does not occur in the information transparency，If it is in GIMP 2.8 Will be automatically added to a transparent color version，2.10 Will not，Therefore solution，Only need to manually add transparent color version can be solved。
#"Layers" - "transparency"，Select "Join transparent color version."。
# Then they can choose "the color into Alpha" function。
【參考連結】
- Color to alpha now requires an alpha-channel (used to add one automatically) (#1975) · Issues · GNOME / GIMP · GitLab
