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I found in Level 2A Product Format Specifications Technical Note page29 that:

"The L2A Quantification Value is aligned with the L1C Quantification Value of the L1C product from which the L2A product is generated"

When I refer to Sentinel-2 Products Specification Document page 403 I found the following:

Sentinel-2 Products Specification Document page 403 Sentinel 2 MSI - Level 2A Product Format Specifications Technical Note page29 Why would the range of values of Level 1C images be 1 to 65535 if the images are supposed to be 12 bits. And what is the range than of Level 2A, is it 0 to 10000?

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The Sentinel 2 L1C images started out as 12-bit, but that has been changed in early 2016 when ESA changed QUANTIFICATION_VALUE from 1000 to 10000. Now L1C is encoded as an UINT16 jp2 file with (at least?) 15 significant bits. This is from gdalinfo on a recent B02.jp2 file:

Band 1 Block=1024x1024 Type=UInt16, ColorInterp=Gray
  Overviews: 5490x5490, 2745x2745, 1372x1372, 686x686
  Overviews: arbitrary
  Image Structure Metadata:
    COMPRESSION=JPEG2000
    NBITS=15

Taking this into account, the limit seems to be 32767 rather than 65535. Any JPEG2000 reader will return the sample value as two bytes, so any code that expects a 16 bit image is safe even if NBITS changes to 16 in the future.

Another note - the product metadata.xml that comes with all L1C tiles contains info about special NO_DATA and SATURATED values, which in recent products looks like this:

<Special_Values>
    <SPECIAL_VALUE_TEXT>NODATA</SPECIAL_VALUE_TEXT
    <SPECIAL_VALUE_INDEX>0</SPECIAL_VALUE_INDEX>
</Special_Values>
<Special_Values>
    <SPECIAL_VALUE_TEXT>SATURATED</SPECIAL_VALUE_TEXT
    <SPECIAL_VALUE_INDEX>65535</SPECIAL_VALUE_INDEX>
</Special_Values>

The SATURATED value of 65535 indicates that the intent was indeed to use the full range of uint16.

As for L2A, if the algorithm ideally corrected all specular reflections, DEM misregistration, emmited radiation and other causes of higher-than-100% reflectance, you should get output in the range 0..10000. Because no atmospheric correction is ideal, you can expect some values to be outside this range, most probably up to 65534, with 65535 again reserved for SATURATED pixels.

  • 3
    Excellent answer Miha. Just note that surface reflectances can be greater than 1. For instance the reflectance you will observe over a mirror in the specular direction or the reflectance of a cloud or of snow in a slope facing the sun direction. What can't be above one is the albedo, which sums the reflected light in all directions. – O. Hagolle Mar 30 '17 at 7:05
  • @O.Hagolle Thanks. Is there an accepted definition of surface reflectance, or some sort of categorization of different kinds of level-2 reflectances, that would help in understanding the possibility of atmospherically corrected data with such effects as you mention? – mkadunc Apr 2 '17 at 22:37
  • rho=Pi.L/ES.COs(Sun Zenith) – O. Hagolle Apr 6 '17 at 15:52

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