title: Values change when convert geotiff to netcdf
body: <p>I have a geotiff which has values from 0 to 200, and a nodata value of 255.
  I converted it to a netcdf with gdal in python:</p>
  <pre><code>ds = gdal.Translate(outputfile, inputfile, format='NetCDF')
  </code></pre>
  <p>[As suggested by Val I tried adding <code>outputType=gdal.gdalconst.GDT_Byte, noData=255</code> but it did not solve either]</p>
  <p>Now all the 0s and nodata values in the netcdf are 0. But the main problem is the other values now range from 127 to -128. The highest values from the tif are now the lowest (i.e. negative) and the lowest values are now the most positive.</p>
  <p>Here is info from the netcdf on the data layer</p>
  <pre><code>&lt;class 'netCDF4._netCDF4.Variable'&gt;
  int8 Band1(y, x)
      long_name: GDAL Band Number 1
      _Unsigned: true
      valid_range: [  0 255]
      _FillValue: 0
      grid_mapping: polar_stereographic
  unlimited dimensions: 
  current shape = (752, 752)
  filling on
  </code></pre>
  <p>Here is the gdal.Info for the netcdf:</p>
  <pre><code>Driver: netCDF/Network Common Data Format
  Files: /Users/clip_asi-AMSR2-s3125-20200305-v5.4.nc
  Size is 117, 163
  Coordinate System is:
  PROJCRS[&quot;IDL GeoTIFF Suport
  Projection = Polar Stereographic
  True scale:      -70.0000deg
  Gunnar Spreen, Apr 2004&quot;,
      BASEGEOGCRS[&quot;WGS 84&quot;,
          DATUM[&quot;World Geodetic System 1984&quot;,
              ELLIPSOID[&quot;WGS 84&quot;,6378137,298.257223563,
                  LENGTHUNIT[&quot;metre&quot;,1]]],
          PRIMEM[&quot;Greenwich&quot;,0,
              ANGLEUNIT[&quot;degree&quot;,0.0174532925199433]],
          ID[&quot;EPSG&quot;,4326]],
      CONVERSION[&quot;unnamed&quot;,
          METHOD[&quot;Polar Stereographic (variant B)&quot;,
              ID[&quot;EPSG&quot;,9829]],
          PARAMETER[&quot;Latitude of standard parallel&quot;,-70,
              ANGLEUNIT[&quot;degree&quot;,0.0174532925199433],
              ID[&quot;EPSG&quot;,8832]],
          PARAMETER[&quot;Longitude of origin&quot;,0,
              ANGLEUNIT[&quot;degree&quot;,0.0174532925199433],
              ID[&quot;EPSG&quot;,8833]],
          PARAMETER[&quot;False easting&quot;,0,
              LENGTHUNIT[&quot;metre&quot;,1],
              ID[&quot;EPSG&quot;,8806]],
          PARAMETER[&quot;False northing&quot;,0,
              LENGTHUNIT[&quot;metre&quot;,1],
              ID[&quot;EPSG&quot;,8807]]],
      CS[Cartesian,2],
          AXIS[&quot;easting&quot;,north,
              ORDER[1],
              LENGTHUNIT[&quot;metre&quot;,1]],
          AXIS[&quot;northing&quot;,north,
              ORDER[2],
              LENGTHUNIT[&quot;metre&quot;,1]]]
  Data axis to CRS axis mapping: 1,2
  Origin = (-1810937.500000000000000,-554687.500000000000000)
  Pixel Size = (3125.000000000000000,-3125.000000000000000)
  Metadata:
    Band1#grid_mapping=polar_stereographic
    Band1#long_name=GDAL Band Number 1
    Band1#valid_range={0,255}
    Band1#_FillValue=-1
    Band1#_Unsigned=true
    NC_GLOBAL#Conventions=CF-1.5
    NC_GLOBAL#GDAL=GDAL 3.0.2, released 2019/10/28
    NC_GLOBAL#GDAL_AREA_OR_POINT=Area
    NC_GLOBAL#GDAL_TIFFTAG_DATETIME=2020:03:06 05:10:59
    NC_GLOBAL#GDAL_TIFFTAG_DOCUMENTNAME=/ssmi/www/htdocs/data/amsr2/asi_daygrid_swath/s3125/2020/mar/Amundsen/asi-AMSR2-s3125-20200305-v5.4.tif
    NC_GLOBAL#GDAL_TIFFTAG_IMAGEDESCRIPTION=IDL TIFF file
    NC_GLOBAL#GDAL_TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
    NC_GLOBAL#GDAL_TIFFTAG_SOFTWARE=IDL 8.1, ITT Visual Information Solutions
    NC_GLOBAL#GDAL_TIFFTAG_XRESOLUTION=100
    NC_GLOBAL#GDAL_TIFFTAG_YRESOLUTION=100
    NC_GLOBAL#history=Wed Mar 31 18:36:11 2021: GDAL CreateCopy( /Users/gjmacdonald/Downloads/clip_asi-AMSR2-s3125-20200305-v5.4.nc, ... )
    polar_stereographic#false_easting=0
    polar_stereographic#false_northing=0
    polar_stereographic#GeoTransform=-1810937.5 3125 0 -554687.5 0 -3125 
    polar_stereographic#grid_mapping_name=polar_stereographic
    polar_stereographic#inverse_flattening=298.257223563
    polar_stereographic#latitude_of_projection_origin=-90
    polar_stereographic#longitude_of_prime_meridian=0
    polar_stereographic#long_name=CRS definition
    polar_stereographic#semi_major_axis=6378137
    polar_stereographic#spatial_ref=PROJCS[&quot;IDL GeoTIFF Suport
  Projection = Polar Stereographic
  True scale:      -70.0000deg
  Gunnar Spreen, Apr 2004&quot;,GEOGCS[&quot;WGS 84&quot;,DATUM[&quot;WGS_1984&quot;,SPHEROID[&quot;WGS 84&quot;,6378137,298.257223563,AUTHORITY[&quot;EPSG&quot;,&quot;7030&quot;]],AUTHORITY[&quot;EPSG&quot;,&quot;6326&quot;]],PRIMEM[&quot;Greenwich&quot;,0],UNIT[&quot;degree&quot;,0.0174532925199433,AUTHORITY[&quot;EPSG&quot;,&quot;9122&quot;]],AUTHORITY[&quot;EPSG&quot;,&quot;4326&quot;]],PROJECTION[&quot;Polar_Stereographic&quot;],PARAMETER[&quot;latitude_of_origin&quot;,-70],PARAMETER[&quot;central_meridian&quot;,0],PARAMETER[&quot;false_easting&quot;,0],PARAMETER[&quot;false_northing&quot;,0],UNIT[&quot;metre&quot;,1],AXIS[&quot;Easting&quot;,NORTH],AXIS[&quot;Northing&quot;,NORTH]]
    polar_stereographic#standard_parallel=-70
    polar_stereographic#straight_vertical_longitude_from_pole=0
    x#long_name=x coordinate of projection
    x#standard_name=projection_x_coordinate
    x#units=m
    y#long_name=y coordinate of projection
    y#standard_name=projection_y_coordinate
    y#units=m
  Corner Coordinates:
  Upper Left  (-1810937.500, -554687.500) (107d 1'47.10&quot;W, 72d38'40.82&quot;S)
  Lower Left  (-1810937.500,-1064062.500) (120d26'14.82&quot;W, 70d47' 7.34&quot;S)
  Upper Right (-1445312.500, -554687.500) (110d59'45.57&quot;W, 75d46'46.47&quot;S)
  Lower Right (-1445312.500,-1064062.500) (126d21'39.97&quot;W, 73d32'29.83&quot;S)
  Center      (-1628125.000, -809375.000) (116d25'58.56&quot;W, 73d19'46.09&quot;S)
  Band 1 Block=117x1 Type=Byte, ColorInterp=Undefined
    NoData Value=255
    Metadata:
      grid_mapping=polar_stereographic
      long_name=GDAL Band Number 1
      NETCDF_VARNAME=Band1
      valid_range={0,255}
      _FillValue=-1
      _Unsigned=true
  </code></pre>
  <p>And the gdal.Info for the converted Tif (after adding Val's suggestion in answers)</p>
  <pre><code>Driver: GTiff/GeoTIFF
  Files: /Users/clip_asi-AMSR2-s3125-20200305-v5.4.tif
  Size is 117, 163
  Coordinate System is:
  PROJCRS[&quot;IDL GeoTIFF Suport
  Projection = Polar Stereographic
  True scale:      -70.0000deg
  Gunnar Spreen, Apr 2004&quot;,
      BASEGEOGCRS[&quot;WGS 84&quot;,
          DATUM[&quot;World Geodetic System 1984&quot;,
              ELLIPSOID[&quot;WGS 84&quot;,6378137,298.257223563,
                  LENGTHUNIT[&quot;metre&quot;,1]]],
          PRIMEM[&quot;Greenwich&quot;,0,
              ANGLEUNIT[&quot;degree&quot;,0.0174532925199433]],
          ID[&quot;EPSG&quot;,4326]],
      CONVERSION[&quot;unnamed&quot;,
          METHOD[&quot;Polar Stereographic (variant B)&quot;,
              ID[&quot;EPSG&quot;,9829]],
          PARAMETER[&quot;Latitude of standard parallel&quot;,-70,
              ANGLEUNIT[&quot;degree&quot;,0.0174532925199433],
              ID[&quot;EPSG&quot;,8832]],
          PARAMETER[&quot;Longitude of origin&quot;,0,
              ANGLEUNIT[&quot;degree&quot;,0.0174532925199433],
              ID[&quot;EPSG&quot;,8833]],
          PARAMETER[&quot;False easting&quot;,0,
              LENGTHUNIT[&quot;metre&quot;,1],
              ID[&quot;EPSG&quot;,8806]],
          PARAMETER[&quot;False northing&quot;,0,
              LENGTHUNIT[&quot;metre&quot;,1],
              ID[&quot;EPSG&quot;,8807]]],
      CS[Cartesian,2],
          AXIS[&quot;easting&quot;,north,
              ORDER[1],
              LENGTHUNIT[&quot;metre&quot;,1]],
          AXIS[&quot;northing&quot;,north,
              ORDER[2],
              LENGTHUNIT[&quot;metre&quot;,1]]]
  Data axis to CRS axis mapping: 1,2
  Origin = (-1810937.500000000000000,-554687.500000000000000)
  Pixel Size = (3125.000000000000000,-3125.000000000000000)
  Metadata:
    AREA_OR_POINT=Area
    TIFFTAG_DATETIME=2020:03:06 05:10:59
    TIFFTAG_DOCUMENTNAME=/ssmi/www/htdocs/data/amsr2/asi_daygrid_swath/s3125/2020/mar/Amundsen/asi-AMSR2-s3125-20200305-v5.4.tif
    TIFFTAG_IMAGEDESCRIPTION=IDL TIFF file
    TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
    TIFFTAG_SOFTWARE=IDL 8.1, ITT Visual Information Solutions
    TIFFTAG_XRESOLUTION=100
    TIFFTAG_YRESOLUTION=100
  Image Structure Metadata:
    INTERLEAVE=BAND
  Corner Coordinates:
  Upper Left  (-1810937.500, -554687.500) (107d 1'47.10&quot;W, 72d38'40.82&quot;S)
  Lower Left  (-1810937.500,-1064062.500) (120d26'14.82&quot;W, 70d47' 7.34&quot;S)
  Upper Right (-1445312.500, -554687.500) (110d59'45.57&quot;W, 75d46'46.47&quot;S)
  Lower Right (-1445312.500,-1064062.500) (126d21'39.97&quot;W, 73d32'29.83&quot;S)
  Center      (-1628125.000, -809375.000) (116d25'58.56&quot;W, 73d19'46.09&quot;S)
  Band 1 Block=117x70 Type=Byte, ColorInterp=Palette
    NoData Value=255
    Color Table (RGB with 256 entries)
      0: 0,0,138,255
      1: 0,0,138,255
      2: 0,0,138,255
      3: 0,0,138,255
      4: 0,0,138,255
      5: 0,0,138,255
      6: 0,0,138,255
      7: 0,0,138,255
      8: 0,0,138,255
      9: 0,0,138,255
     10: 0,0,138,255
     11: 0,0,138,255
     12: 0,0,138,255
     13: 0,0,138,255
     14: 0,0,138,255
     15: 0,0,138,255
     16: 0,0,138,255
     17: 0,0,138,255
     18: 0,0,138,255
     19: 0,0,138,255
     20: 29,143,254,255
     21: 29,143,254,255
     22: 29,143,254,255
     23: 29,143,254,255
     24: 29,143,254,255
     25: 29,143,254,255
     26: 29,143,254,255
     27: 29,143,254,255
     28: 29,143,254,255
     29: 29,143,254,255
     30: 29,143,254,255
     31: 29,143,254,255
     32: 29,143,254,255
     33: 29,143,254,255
     34: 29,143,254,255
     35: 29,143,254,255
     36: 29,143,254,255
     37: 29,143,254,255
     38: 29,143,254,255
     39: 29,143,254,255
     40: 29,249,159,255
     41: 29,249,159,255
     42: 29,249,159,255
     43: 29,249,159,255
     44: 29,249,159,255
     45: 29,249,159,255
     46: 29,249,159,255
     47: 29,249,159,255
     48: 29,249,159,255
     49: 29,249,159,255
     50: 29,249,159,255
     51: 29,249,159,255
     52: 29,249,159,255
     53: 29,249,159,255
     54: 29,249,159,255
     55: 29,249,159,255
     56: 29,249,159,255
     57: 29,249,159,255
     58: 29,249,159,255
     59: 29,249,159,255
     60: 33,138,33,255
     61: 33,138,33,255
     62: 33,138,33,255
     63: 33,138,33,255
     64: 33,138,33,255
     65: 33,138,33,255
     66: 33,138,33,255
     67: 33,138,33,255
     68: 33,138,33,255
     69: 33,138,33,255
     70: 33,138,33,255
     71: 33,138,33,255
     72: 33,138,33,255
     73: 33,138,33,255
     74: 33,138,33,255
     75: 33,138,33,255
     76: 33,138,33,255
     77: 33,138,33,255
     78: 33,138,33,255
     79: 33,138,33,255
     80: 0,249,0,255
     81: 0,249,0,255
     82: 0,249,0,255
     83: 0,249,0,255
     84: 0,249,0,255
     85: 0,249,0,255
     86: 0,249,0,255
     87: 0,249,0,255
     88: 0,249,0,255
     89: 0,249,0,255
     90: 0,249,0,255
     91: 0,249,0,255
     92: 0,249,0,255
     93: 0,249,0,255
     94: 0,249,0,255
     95: 0,249,0,255
     96: 0,249,0,255
     97: 0,249,0,255
     98: 0,249,0,255
     99: 0,249,0,255
    100: 124,249,0,255
    101: 124,249,0,255
    102: 124,249,0,255
    103: 124,249,0,255
    104: 124,249,0,255
    105: 124,249,0,255
    106: 124,249,0,255
    107: 124,249,0,255
    108: 124,249,0,255
    109: 124,249,0,255
    110: 124,249,0,255
    111: 124,249,0,255
    112: 124,249,0,255
    113: 124,249,0,255
    114: 124,249,0,255
    115: 124,249,0,255
    116: 124,249,0,255
    117: 124,249,0,255
    118: 124,249,0,255
    119: 124,249,0,255
    120: 172,254,46,255
    121: 172,254,46,255
    122: 172,254,46,255
    123: 172,254,46,255
    124: 172,254,46,255
    125: 172,254,46,255
    126: 172,254,46,255
    127: 172,254,46,255
    128: 172,254,46,255
    129: 172,254,46,255
    130: 172,254,46,255
    131: 172,254,46,255
    132: 172,254,46,255
    133: 172,254,46,255
    134: 172,254,46,255
    135: 172,254,46,255
    136: 172,254,46,255
    137: 172,254,46,255
    138: 172,254,46,255
    139: 172,254,46,255
    140: 249,249,0,255
    141: 249,249,0,255
    142: 249,249,0,255
    143: 249,249,0,255
    144: 249,249,0,255
    145: 249,249,0,255
    146: 249,249,0,255
    147: 249,249,0,255
    148: 249,249,0,255
    149: 249,249,0,255
    150: 249,249,0,255
    151: 249,249,0,255
    152: 249,249,0,255
    153: 249,249,0,255
    154: 249,249,0,255
    155: 249,249,0,255
    156: 249,249,0,255
    157: 249,249,0,255
    158: 249,249,0,255
    159: 249,249,0,255
    160: 249,124,0,255
    161: 249,124,0,255
    162: 249,124,0,255
    163: 249,124,0,255
    164: 249,124,0,255
    165: 249,124,0,255
    166: 249,124,0,255
    167: 249,124,0,255
    168: 249,124,0,255
    169: 249,124,0,255
    170: 249,0,0,255
    171: 249,0,0,255
    172: 249,0,0,255
    173: 249,0,0,255
    174: 249,0,0,255
    175: 249,0,0,255
    176: 249,0,0,255
    177: 249,0,0,255
    178: 249,0,0,255
    179: 249,0,0,255
    180: 185,84,210,255
    181: 185,84,210,255
    182: 185,84,210,255
    183: 185,84,210,255
    184: 185,84,210,255
    185: 185,84,210,255
    186: 185,84,210,255
    187: 185,84,210,255
    188: 185,84,210,255
    189: 185,84,210,255
    190: 147,0,210,255
    191: 147,0,210,255
    192: 147,0,210,255
    193: 147,0,210,255
    194: 147,0,210,255
    195: 147,0,210,255
    196: 147,0,210,255
    197: 147,0,210,255
    198: 147,0,210,255
    199: 119,0,89,255
    200: 119,0,89,255
    201: 0,0,0,255
    202: 0,0,0,255
    203: 0,0,0,255
    204: 0,0,0,255
    205: 0,0,0,255
    206: 0,0,0,255
    207: 0,0,0,255
    208: 0,0,0,255
    209: 0,0,0,255
    210: 0,0,0,255
    211: 0,0,0,255
    212: 0,0,0,255
    213: 0,0,0,255
    214: 0,0,0,255
    215: 0,0,0,255
    216: 0,0,0,255
    217: 0,0,0,255
    218: 0,0,0,255
    219: 0,0,0,255
    220: 0,0,0,255
    221: 0,0,0,255
    222: 0,0,0,255
    223: 0,0,0,255
    224: 0,0,0,255
    225: 0,0,0,255
    226: 0,0,0,255
    227: 0,0,0,255
    228: 0,0,0,255
    229: 0,0,0,255
    230: 0,0,0,255
    231: 0,0,0,255
    232: 0,0,0,255
    233: 0,0,0,255
    234: 0,0,0,255
    235: 0,0,0,255
    236: 0,0,0,255
    237: 0,0,0,255
    238: 0,0,0,255
    239: 0,0,0,255
    240: 0,0,0,255
    241: 0,0,0,255
    242: 0,0,0,255
    243: 0,0,0,255
    244: 0,0,0,255
    245: 0,0,0,255
    246: 0,0,0,255
    247: 0,0,0,255
    248: 0,0,0,255
    249: 0,0,0,255
    250: 0,0,0,255
    251: 99,99,99,255
    252: 0,0,0,255
    253: 0,0,0,255
    254: 0,0,0,255
    255: 0,0,0,0
  </code></pre>
  <p>Tif file:
  <a href="https://drive.google.com/file/d/1y5UGAteXUOzGaqWsuFc7DXi8XTzGMVJ_/view?usp=sharing" rel="nofollow noreferrer">https://drive.google.com/file/d/1y5UGAteXUOzGaqWsuFc7DXi8XTzGMVJ_/view?usp=sharing</a>
  Converted nc file: <a href="https://drive.google.com/file/d/1CjZJ9pRcLJomHMkTjatkXHTKx4zQ6ehl/view?usp=sharing" rel="nofollow noreferrer">https://drive.google.com/file/d/1CjZJ9pRcLJomHMkTjatkXHTKx4zQ6ehl/view?usp=sharing</a></p>