You may want to read PMC3998685 and see earlier posts in this fourm
  https://www.nitrc.org/forum/forum.php?th...
In brief, Phiips stores two ways of scaling raw data to intensity values: the display value and the precise floating point value. For example, if the raw data is 12-bit precision (values 0..4095) and the display range is intercept=0 and slope = 0.0625, then the pixels values will be in the range 0..255. The same image might report the precise values to have an intercept of 0 and a slope or 2, in which case the float values would be in the range 0..8190. NIfTI requires a single conversion from the raw values to the image intensities, so the user needs to choose between these. This does not matter with most MRI modalities, as the intensities are relative and so it does not matter how you scale the data: in both cases the raw data is identical. However, for some images (e.g. ADC) these units may be meaningful. 

This behavior is not defined by DICOM, and my software simply allows you to choose a preference between the two options provided by your vendor. One would think that the "precise" values would always be preferable, and the others are simply used to match the arbitrary calibration of a computer monitor, but some users seem to prefer the display values. Maybe Philips can provide you with their logic for these values.