hugin-devs team mailing list archive

[Alex Romosan <2064625@xxxxxxxxxxxxxxxxxx>]

for an iPhone 8

zoomed:

Make                            : Apple
Camera Model Name               : iPhone 8
Focal Length                    : 4.0 mm
Focal Length In 35mm Format     : 141 mm
Digital Zoom Ratio              : 5.006622517

non zoomed:

Make                            : Apple
Camera Model Name               : iPhone 8
Focal Length                    : 4.0 mm
Focal Length In 35mm Format     : 28 mm

for iPhone6

zoomed:

Make                            : Apple
Camera Model Name               : iPhone 6
Focal Length                    : 4.2 mm
Focal Length In 35mm Format     : 145 mm
Digital Zoom Ratio              : 4.995918367

non zoomed

Make                            : Apple
Camera Model Name               : iPhone 6
Focal Length                    : 4.2 mm
Focal Length In 35mm Format     : 29 mm

iphoneSE 3rd generation:

zoomed:

Make                            : Apple
Camera Model Name               : iPhone SE (3rd generation)
Focal Length                    : 4.0 mm
Focal Length In 35mm Format     : 55 mm
Digital Zoom Ratio              : 1.950967742

non zoomed:

Make                            : Apple
Camera Model Name               : iPhone SE (3rd generation)
Focal Length                    : 4.0 mm
Focal Length In 35mm Format     : 28 mm

I'm getting data for two more iPhone models tomorrow and all add to
this.

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https://bugs.launchpad.net/bugs/2064625

Title:
  35mm focal length on iPhone SE3 2nd generation over corrercted

Status in Hugin:
  Incomplete

Bug description:
  This is for an iPhone SE 3rd generation. Looking at the exif data for
  a zoomed picture I can see:

  Lens Specification  |3.990000, 3.990000, 1.8, 1.8
  Lens Make           |Apple
  Lens Model          |iPhone SE (3rd generation) back camera 3.99mm f/1.8
  Digital Zoom Ratio  |1.951
  Focal Length in 35mm|55

  For a normal picture:

  Focal Length in 35mm|28
  Scene Capture Type  |Standard
  Lens Specification  |3.990000, 3.990000, 1.8, 1.8
  Lens Make           |Apple
  Lens Model          |iPhone SE (3rd generation) back camera 3.99mm f/1.8

  Turns out the reported focal length for a zoomed picture is already
  corrected for the digital zoom factor so
  src/hugin_base/panodata/SrcPanoImage.cpp:542 over corrects by
  multiplying again with the digital zoom factor ending up with an hFOV
  too small. I just commented out line 542 and now when I add the zoomed
  picture I get an hFOV of 34.9 (which is what I would expect) instead
  of 18.3 (wrong).

  --- a/src/hugin_base/panodata/SrcPanoImage.cpp  Wed May 01 19:41:11 2024 +0200
  +++ b/src/hugin_base/panodata/SrcPanoImage.cpp  Thu May 02 15:18:02 2024 +0200
  @@ -539,7 +539,7 @@
       const float digitalZoom = Exiv2Helper::getExiv2ValueDouble(exifData, "Exif.Photo.DigitalZoomRatio");
       if (eFocalLength35 > 0 && digitalZoom > 1)
       {
  -        eFocalLength35 *= digitalZoom;
  +    //    eFocalLength35 *= digitalZoom;
       };
       float focalLength=0;
       //The various methods to detmine crop factor

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