Have you tried displaying BOTH the original image and the resized images? My guess is that the original image will display with the correct orientation, but the resized image will not because the original image has the required EXIF data that the browser is applying while the resized image does not. The user manual for imagecreatefromjpeg() has the following user contributed note:
This function does not honour EXIF orientation data. Pictures that are rotated using EXIF, will show up in the original orientation after being handled by imagecreatefromjpeg(). Below is a function to create an image from JPEG while honouring EXIF orientation data
Even though an image displays correctly on the iPhone does not mean it is really saved that way. The camera has a specific orientation and I suspect all images are saved with that default orientation. All the rotation implementation is likely just software based.
For a PHP application, I would not rely upon EXIF information to determine how an image is displayed. I would instead convert the image (as the example with that note would do) so it does not depend on rotation. The reason is if you need to do any logic on the size of the image it would be more complicated. For example, if you will create the output differently based on the width of an image you would have to first check the EXIF data to determine if you should check the "width" or the "height" of the image based on what is the real width when displayed
Since you already have a process to resize the original image go ahead and rotate the new image accordingly. If you also save the original image, then you should replace it with one that is not rotated as well.Go to the full post