JEITA  CP-3451  Explication - 137 - 7.3    Tag Use in Readers Readers can make use of the information recorded as tags in an Exif file to perform optimal image processing. The following tags are useful for photo retouch processing and their use is to be encouraged whenever possible.   a) ExposureMode b) WhiteBalance c) Flash d) SceneCaptureType e) ExposureTime f) CustomRendered 7.3.1    ExposureTime Tag Information Exposure time, given in seconds (sec). [Reader] �|When exposure time is unusually long, the reader can assume the possibility of noise occurring. �|Other tags (brightness, shutter speed, gain control, captured scene type, etc.) may be used as supplementary information. 7.3.2    BrightnessValue Tag Information The value of brightness. The unit is the APEX value. [Writer] �|The writer should record the brightness of the presumed main subject. When flash is used, the brightness level before firing should be recorded. [Reader] �|The reader may judge the possibility of noise occurring from very low light conditions. �|This tag may be used to determine the weather conditions, etc., in daylight shooting. 7.3.3    LightSource Tag Information Indicates the kind of light source. [Writer] �|The writer should record the light source as estimated by the writer based on white balance, etc., or as set by the user. �|This will sometimes differ from the actual light source used for shooting [Reader] �|This information may be referred to when adjusting white balance.