Eliminating white balancing when using DSS
Posted: Wed Aug 10, 2016 9:11 pm
Hi Ivo
In a number of conversations e.g. here here you talk about using DCRAW to preprocess the subs from Canon DSLRs and convert them to TIFFs before using DSS.
Obviously the main reason to do this being to stop DSS white balancing the image so that we get the best stacked image for StarTools.
As I understand it from here the command is:
dcraw -v -r 1 1 1 1 -4 -T -S 32767 -k 0 -o 0 -q 0 *.CR2
When I use this command the images are rotated and changed so much that I have to reduce the star detection threshold in DSS to around 2% where for the CR2 version it was at 90%. In StarTools the image is very faint.
The rotation can be removed using -t 0 (autoflip image=none)
My questions are:
-k 0 sets the darkness level to 0 - isn't that like setting the black point to 0 in DSS - which I thought was not best practice?
I'd also be interested to understand why the saturation level is set to 32767.
The Canon 1000D camera I am using is 12-bit - does the saturation level need to be set differently for this - or what is the effect if I remove the -S command completely?
Any advice you can give would be appreciated.
Guy
In a number of conversations e.g. here here you talk about using DCRAW to preprocess the subs from Canon DSLRs and convert them to TIFFs before using DSS.
Obviously the main reason to do this being to stop DSS white balancing the image so that we get the best stacked image for StarTools.
As I understand it from here the command is:
dcraw -v -r 1 1 1 1 -4 -T -S 32767 -k 0 -o 0 -q 0 *.CR2
When I use this command the images are rotated and changed so much that I have to reduce the star detection threshold in DSS to around 2% where for the CR2 version it was at 90%. In StarTools the image is very faint.
The rotation can be removed using -t 0 (autoflip image=none)
My questions are:
-k 0 sets the darkness level to 0 - isn't that like setting the black point to 0 in DSS - which I thought was not best practice?
I'd also be interested to understand why the saturation level is set to 32767.
The Canon 1000D camera I am using is 12-bit - does the saturation level need to be set differently for this - or what is the effect if I remove the -S command completely?
Any advice you can give would be appreciated.
Guy