White speckles in image

For discussion of LizardTech's geospatial encoding and manipulation software and general discussion of MrSID and JPEG 2000.

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White speckles in image

Postby rayjoslyn » Tue Jan 26, 2010 11:59 am

When setting my background color to white, I am getting some speckling of white in areas that are nearly all black when compressing to SID at 20:1, why is this? I have tried despeckling, but this doesn't help since these areas are well within my image and not on an edge.

Ray
rayjoslyn
 
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Postby rparker » Thu Feb 04, 2010 10:42 am

Hello,

When you set your background color to white (255), are you leaving the transparency color as black (0)?

The idea is to set both transparency and background to the same value. Otherwise, you will be changing black pixels to white ones.

The mosaicker looks at the value you set for transparency and replaces it with one of two options:

1. Another image in the same area, or if none is there...
2. Replace the pixel with the background color.
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