I am researching how to correct any facial distortions seen on an iPhone's front camera. Here is my current understanding of the issue:
- close-up photos will enlarge nearer facial features such as nose and forehead, as a short camera distance will magnify the discrepancy in camera distance between different features (as opposed to far-away images in which the distance variation between features is 'diluted' due to the long camera distance)
- even though close-up photos will distort images of 3D objects, there does not appear to be any distortion when photographing a 2D image such as a ruler
- wide-angle lenses (as used in iPhones) can cause a barrel distortion effect on images taken at a close distance. I have tested this out but have not found any noticeable barrel distortion
- what is the root cause for image distortion on an iPhone? Is it solely due to perspective distortion, or does the wide-angle lens also play a role?
- is my reasoning correct as to why there is no noticeable distortion for 2D images, regardless of camera distance?
- what is the minimal camera distance at which point there will no longer be a distortion of facial features on an iPhone's front camera?
- is the focal length different between the front and back cameras of an iPhone?