(13-03-2016, 10:31 PM)Starry Dave Wrote: [ -> ]Hi,
I mentioned to my buddy Ken that I was testing SkippyStak but had no data due to bad weather. He kindly gave me a set of M42 raw files shot thru a Canon T2i on a 8" scope. I tried first using the DCRAW conversion in SS and then processed the stack using StarTools to get the image below. Compare this with the image in my next message using DPP>TIFF conversion instead.
This image below was made using TIFFS generated from the original CR2s using DPP's batch convert function. I then processed the result in StarTools using the same workflow as above. You can see that the result is much better than the DCRAW version. It looks like data is being lost when DCRAW does its conversion.
Hi Dave,
That's quite a significant difference! It's not surprising that DPP, as the camera maker's own dedicated software,
should do a bang up job of converting the files.
Of course this may be a case of Mr Stupid in action by choosing sub optimal DCRAW parameters!
These are the parameters that I use in the call to DCRAW : -w -j -W -6 -T
and from the DCRAW Help they relate to :-
-w : Use camera White balance
-j : Don't stretch raw pixels
-W : Do not automatically brighten
-6 : Write 16bit
-T : Write TIFF
Below is the full list of parameters to DCRAW.
If anyone can suggest a better set of parameters than what I've chosen, please speak up.
My simpleton's theory has been to try to do the least change, the least modification possible
to your CR2 files. Maybe that's not such a Good Idea?
If folks thought it useful, I could always put in a series of check boxes and let the User decide
just which DCRAW parameters should be used.
Regards,
Andrew
Raw photo decoder "dcraw" v9.22
by Dave Coffin, dcoffin a cybercom o net
Usage: dcraw [OPTION]... [FILE]...
-v Print verbose messages
-c Write image data to standard output
-e Extract embedded thumbnail image
-i Identify files without decoding them
-i -v Identify files and show metadata
-z Change file dates to camera timestamp
-w Use camera white balance, if possible
-a Average the whole image for white balance
-A <x y w h> Average a grey box for white balance
-r <r g b g> Set custom white balance
+M/-M Use/don't use an embedded color matrix
-C <r b> Correct chromatic aberration
-P <file> Fix the dead pixels listed in this file
-K <file> Subtract dark frame (16-bit raw PGM)
-k <num> Set the darkness level
-S <num> Set the saturation level
-n <num> Set threshold for wavelet denoising
-H [0-9] Highlight mode (0=clip, 1=unclip, 2=blend, 3+=rebuild)
-t [0-7] Flip image (0=none, 3=180, 5=90CCW, 6=90CW)
-o [0-5] Output colorspace (raw,sRGB,Adobe,Wide,ProPhoto,XYZ)
-o <file> Apply output ICC profile from file
-p <file> Apply camera ICC profile from file or "embed"
-d Document mode (no color, no interpolation)
-D Document mode without scaling (totally raw)
-j Don't stretch or rotate raw pixels
-W Don't automatically brighten the image
-b <num> Adjust brightness (default = 1.0)
-g <p ts> Set custom gamma curve (default = 2.222 4.5)
-q [0-3] Set the interpolation quality
-h Half-size color image (twice as fast as "-q 0")
-f Interpolate RGGB as four colors
-m <num> Apply a 3x3 median filter to R-G and B-G
-s [0..N-1] Select one raw image or "all" from each file
-6 Write 16-bit instead of 8-bit
-4 Linear 16-bit, same as "-6 -W -g 1 1"
-T Write TIFF instead of PPM