Error display when loading a 6000 x 3000 jpg by using WWW

I load a 6000x3000 jpg texture from local file by using WWW. When running in editor, it finished the loading but display a error texture. Just some blue color ,not the real image of the file. It's just the same when loading other jpg files with the same resolution. But it's all right loading a 4000 x 2000 jpg file.

And I build a apk of the project, run it on the android system. It display the right Image of the same 6000x3000 jpg file. So, Why it dose not work in Editor?