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Originally posted by qmantoo
This topic is possibly getting hot and slightly controversial and being in the science forum may not attract those willing to discuss or debate that side of things.
If you zoom in to the rocks on the right, the black areas have a kind of overlay around the bottom edges and overlapping the black a fair bit. While there, you can see this 'overlay' extending to the rest of the ground. This is not a regular compression instance as it would either compress the black area or it would not compress any of the black area.
Maybe you can explain why you think it's an overlay?
Originally posted by qmantoo
If you zoom in to the rocks on the right, the black areas have a kind of overlay around the bottom edges and overlapping the black a fair bit. While there, you can see this 'overlay' extending to the rest of the ground. This is not a regular compression instance as it would either compress the black area or it would not compress any of the black area.
Apparently when a thread is not getting any replies, that means the topic is "getting hot"?
Originally posted by Mary Rose
Tell me more, please.
Originally posted by qmantoo
This topic is possibly getting hot and slightly controversial and being in the science forum may not attract those willing to discuss or debate that side of things.
I have said on page 1 why I think it is some kind of overlay - because as far as I understand it, areas of single colour do not get compressed with jpg algorithm and there is a section of what looks like compressed image ( at the bottom-right of the black area explained below). I think this is some kind of 'overlay' on the image which is separate to the compression process.
Maybe you can explain why you think it's an overlay?
I have always enjoyed editing images, especially so that the observer is unable to tell if the finished result was one single image or a result of several images stitched together. That’s where most of my image manipulation experience lies, creating believable images to the degree that the observer doesn’t even know it’s a doctored image.
Originally posted by qmantoo
as far as I understand it, areas of single colour do not get compressed with jpg algorithm
OK, well lets consider the NASA image I posted a link earlier. Considering the 3 large black 'shadow' areas of the rocks in the right of that image (going in a line towards the middle right edge). If we look at the first leftmost of these for a moment.
There is an area at the bottom right of this shadow which looks like compression artifacts. If you look closely however, you can easily see that this extends over the grey ground beneath and to the right of the black shadow. The ground around this rock is totally featureless at that zoom level.
This is not anything to do with compression as there are numerous other grey areas bordering this black shadow which are not similarly marked. Equally, there are other areas apart from this where this 'compression-like overlay' is evident.