https://tinyurl.com/y6pvr5kj
Google Photos giving iPhone unlimited storage at original quality while
snubbing Pixel 4
google photo给iphone无限原版画质储存空间，但pixel 4反而没有
"With all modern iPhones shooting photos in HEIC format, which is smaller
than even Googles compressed JPG files, iPhones therefore get free unlimited
ORIGINAL quality backups simply because it would cost Google both storage
space (because if Google tried to compress iPhones HEIC photos they would
actually become larger) and computing power (because Google doesn't need to
compress and process all of the billions of photos iPhones backup.)
现代的iphone照片是用HEIC格式，其大小甚至比google 压缩的jpg档还要小。iphone
因此可以得到无限的原版画质，因为其实这样google反而可以节省储存空间（因为
压缩完档案还变大）以及计算能力（因为google不用需要去压缩上亿张照片）
So Apple is literally saving Google millions of dollars by shooting their
photos in HEIC and it benefits iPhone users as well because we get free
original quality backups."
所以苹果采用新的相片格式其实帮google省了很多钱，iphone使用者也因此得到原始
画质备份
pixel 4因为还没有办法储存成HEIC格式，所以照片还是会被压缩
但android 10会支援HEIC格式，到时候就可以享受到跟iphone一样的待遇
iphone使用者请记得不要把相片存成jpg档，以免被压缩