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NoData issues: Value of 256 MAP_DOWN for 8-bit raster

Question asked by geonetadmin on Jul 11, 2013
Original User: sarajase

Hello All,

I have number of historic 8-bit single band (panchromatic) aerial photos in mostly TIFF, JP200 or MrSid formats.

These rasters have NoData value of 256. Do not know how it happens.

I am converting them into a different projection using python. I am using the environment setting  "MAP_DOWN".

The assumption is that value 0f 256 becomes 255 and 255 would be NoData. That takes care of NoData value of 256 which was causing issues with serving the imagery.

The problem is that the resultant JP2000 (JP2) rasters are showing few holes in white areas (high values). Is this because of JPEG compression?

When I out put the rasters to TIFF images these pixels have the value of 254 (highest) and the rasters show no holes (NoData) in the middle of images.

Anymore insights? Is there a way to get the JP2s like the TIFFs?

Thanks to all ...