image auto crop like ios question

[YIFanH]

Dear Tim Oliver:

 I am one image processer from china and doing image croping as ios, but how to detect the rotate angle for the auto crop, i do some experiments on this quesion,but can not to find a simple rule. I am Looking forward to your reply.

[TimOliver]

Hi @YIFanH!

Haha sorry, I have no idea how Apple implemented that auto-crop feature in the Photos app. I'm curious about it too, but I'm not even sure what it's doing to the photo to get that information.

Sorry! :(

[TimOliver]

Oh hang on! I spoke too soon!

It's a Core Image filter! Go to the Core Image Class Reference Page and there's a method called [CIImage autoAdjustmentFiltersWithOptions:]. One of the options you can pick is kCIImageAutoAdjustCrop.

Good luck!

[YIFanH]

@TimOliver
Thanks for your reply, I uesd the lines and vanishing point feature to find the rotate angle, but the results is is different with the ios. I guess the ios only used the lines feature,So i make the special image which only have some lines,but can not find a simple rules to find angle。