John Andrade created IMAGING-285:
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Summary: Decoding of Rational Numbers broken when large values
present
Key: IMAGING-285
URL: https://issues.apache.org/jira/browse/IMAGING-285
Project: Commons Imaging
Issue Type: Bug
Components: imaging.common.*
Affects Versions: 1.0-alpha2
Reporter: John Andrade
Attachments: DJI_0267 cropped.JPG
Decoding Lat/Long EXIF data from JPEGs does not work for some values. I have
attached a file where the conversion fails. I used the
getLatitudeAsDegreesNorth and getLongitudeAsDegreesEast methods from the
TiffImageMetaData.GPSInfo class. The values are close, but seemingly off by a
few miles.
I've traced the source and I believe the issue is with how the RationalNumber
class uses two 32-bit signed integers for the numerator and denominator. The
definition of a RATIONAL data type uses 32-bit unsigned numbers. It seems as
if the RationalNumber class already expects this as it has a non-public static
method called factoryMethod to create a RationalNumber from two 64-bit numbers.
This error is introduced in the ByteConversions class, specifically the
toRational method where it uses the regular RationalNumber constructor and thus
ensures any rational numbers that have numerator or denominator greater than
the max signed 32-bit value will produce invalid values.
I am attaching a JPEG that has this problem. I had to crop it to reduce the
size, but the EXIF data was preserved.
The EXIF GPS data contained in the JPEG is:
GpsLatitudeRef: "N"
GpsLatitude: 38, 1, 36, 1, 4120083230, 70000000
GpsLongitudeRef: "W"
GpsLongitude: 90, 1, 12, 1, 2379156648, 70000000
According to the properties of the image (right-clicking on Windows 10), the
L/L of the image is:
Latitude: 38: 36: 58.85833....
Longitude: 90: 12: 33.98795... (Windows doesn't show E/W)
These values convert to:
38.616349536627
-90.2094410978095
When I use the getLatitudeAsDegreesNorth and getLongitudeAsDegreesEast
methods, I get the following values:
38.59930601561111
-90.19239757679365
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