CompressionQuality artefacts

[arvisam 0]

Hi!I'm experimenting with some large scale photoreal water masks using BlueMarble imagery. Due to the large size of the imagery (I am working with 3 arc deg x 3 arc deg cells), I had to use CompressionQuality = 80 to keep the size of the BGL within reasonable sizes. While things are mostly working out, I have a problem with the boundary between adjacent cells, where there is a dark border which appears only when I use low CompressionQuality values (the problem does not occur when CompressionQuality = 100).I presume this is due to the compression algorithm, but I'd like to understand why the artefact only appears on the border and not inside the image. I'd also like to hear from others if they have seen something like this before and what we can do about it.

[arno 1]

Hi,I have also seen this sometimes, but mainly in parts of the imagery that use very monotonous colours (so all the same or very similar colours). I have not seen it in other parts of the imagery. Is that similar to what you see?

[arvisam 0]

Hi,I have also seen this sometimes, but mainly in parts of the imagery that use very monotonous colours (so all the same or very similar colours). I have not seen it in other parts of the imagery. Is that similar to what you see?

Yes Arno, it is at the edges of the BlueMarble tile I have extracted. And yes, it seems to occur in places of 'monotonous' color (deep ocean water). I will try to add some 'noise' using some image programs and test the results.

[arno 1]

Hi,

Yes Arno, it is at the edges of the BlueMarble tile I have extracted. And yes, it seems to occur in places of 'monotonous' color (deep ocean water). I will try to add some 'noise' using some image programs and test the results.

What we did in the end is not use the water from the photo, but add a watermask to show the default FSX water in the end. Not sure if that is an option to you as well.