gogopix
Graf
On the DPreviw forum there was a thread by Andrej Kolev who is trying to make a DNG raw converter.He may have broken the code on why the M8 has only 10MB files and the DMR 20MB.
He says the M8 files have only 8 bits per channel rather than 16, but that they are non linear mapping to 14 bit luminance range per color RGB. That means in fact M8 has less information than DMR - since the DMR is linear and 16 bit.
When you map 8 bits non-linear to 14-bits linear you can recover dynamic range but you do lose detail,since you dont know all the gradations in between. I wonder why Leica would do this.
It could be he is wrong, and the lossless compression just codes redundancy and thus all detail can be recovered (just mapping 8 bit to 14 bits will NOT do it.
There are a lot of situations where non linear mappings lose very little since the eye (as well as ear) are logrithmic devices, that is, it can take a factor of 10 i nsound to have a perceived 'doubling' of sound (that is why 10-20 db is about 'twice' as loud perceived, but sound energy is actually 10 times!
maybe Leica tested and found a clever mapping that preserves detail, but going from 20MB per image to 10 MB for same number of pixels is half the infrormation. Whether it makes any difference only time will tell. If the coding uses redundacy(like patches of same color) and just compresse more cleverly, well then nothing will be lost.
But since we have SO much time on our hands I thought it would be interesting to speculate on something besides lenses and Seals
Ok, Ok many will notice same topic a few fora. I want to see where the technical guys are!
So who can address this? (BTW images may not REALLY be affected)
Victor
PS Pre-order FIRMLY staying in place 🙂
He says the M8 files have only 8 bits per channel rather than 16, but that they are non linear mapping to 14 bit luminance range per color RGB. That means in fact M8 has less information than DMR - since the DMR is linear and 16 bit.
When you map 8 bits non-linear to 14-bits linear you can recover dynamic range but you do lose detail,since you dont know all the gradations in between. I wonder why Leica would do this.
It could be he is wrong, and the lossless compression just codes redundancy and thus all detail can be recovered (just mapping 8 bit to 14 bits will NOT do it.
There are a lot of situations where non linear mappings lose very little since the eye (as well as ear) are logrithmic devices, that is, it can take a factor of 10 i nsound to have a perceived 'doubling' of sound (that is why 10-20 db is about 'twice' as loud perceived, but sound energy is actually 10 times!
maybe Leica tested and found a clever mapping that preserves detail, but going from 20MB per image to 10 MB for same number of pixels is half the infrormation. Whether it makes any difference only time will tell. If the coding uses redundacy(like patches of same color) and just compresse more cleverly, well then nothing will be lost.
But since we have SO much time on our hands I thought it would be interesting to speculate on something besides lenses and Seals
Ok, Ok many will notice same topic a few fora. I want to see where the technical guys are!
So who can address this? (BTW images may not REALLY be affected)
Victor
PS Pre-order FIRMLY staying in place 🙂
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