Originally posted by arianna
Then you should make contact with the software people at Adobe,
I'm sure they would like to hear from you about the removal of artefacts is being delusional.
....you just don't get it.
Any software, or person(s), or company that claims it can remove compression artifacts is only talking cosmetically
. They don't actually
remove the artifacts, they only manipulate the image to hide the artifacts.
Like this guy for example:
He is not actually removing the artifacts. He is just manipulating the image to hide the artifacts.
You know what compression is, right? Compression is used to reduce the size of data.
With computer files and other sensitive data where every bit needs to be perfect, you need lossless compression algorithms that don't lose any data
during the compression. So when you DECOMPRESS the data you end up with an exact replica of the original uncompressed data.
There are many methods to losslessly compress data, but most do the following; Find parts of the data that are identical, save only one of the
identical parts as a definition, then replace all of the identical parts with a pointer to the definition. That way you save space because you don't
have duplicate data. When the file is decompressed, the pointers are replaced with their definitions, and the data is restored.
With images and videos, sounds and music, some bits can be modified and or completely removed and it wouldn't matter because most human ears and eyes
would hardly notice. So lossy compression can be used, which actually modifies and or completely removes data that is unnecessary. With lossy
compression you CAN NOT DECOMPRESS the data and end up with an exact replica of the original uncompressed data because some data was lost!
There are many lossy compression methods, but most do the following; Find parts of the data that are very similar but not identical, and near each
other. For example the color black (0,0,0) and a very dark grey (3,3,3). Then replace one or the other so they are identical. So in this case, turn
dark grey to black because you can hardly see the difference. Essentially, that grey pixel is lost forever. Then, proceed with normal lossless
compression described above. This method "reduces the amount of unique colors", which essentially reduces the amount of definitions and pointers
needed. It is what causes a lot of the blotchy areas you see in compressed images in areas where it used to be smooth. Smoothness requires more
unique colors, and when those unique colors are replaced with common colors during compression, it creates blotchy areas.
Lossy compression is able to compress more than lossless compression because lossy will create identical data where none exists.
When you or anyone claims to be able to remove compression artifacts from an image, you are claiming to be able to completely uncompress data which
was lossy compressed. That is impossible. The only thing you or they did was manipulate the data to hide the effects of lossy compression, and that
data does not represent the original uncompressed data. That manipulated data is artificial.
How about YOU contact Adobe... You will see that they will tell you exactly what I am telling you.
edit on 9-9-2012 by senselessness because:
(no reason given)