Command line: Manipulate DNG exposure

Dear friends,
I am running Windows7, and am looking for a command line utility to
modify the DNG's exposure and save to a new DNG, with the intent of
prepping for HDR processing.

For example, to make -2 and +2 EV modifications, Id like to do something such as:

converterapp "base.dng" -modifyexposure -2 "base-2.dng"
converterapp "base.dng" -modifyexposure +2 "base+2.dng"


I am hoping that whoever is reading this understand that the above is simply for
the sake of explanation.


My google fu is weak, I have searched for 4 weeks and turned up nothing.

May you be of assistance?

I am only interested in solutions that are command line, I can easily do this
with PS but that is not part of this project.

Thanks,
Andrew

Look at the dcraw “brightness” flag. Output 16 bit tiffs

For example:

dcraw -b 0.5 -T -6 <input file name.DNG>

10-4, thanks!

It accomplishes what I want, and does it well! The previous version of DCRAW I had did not process my D5300 NEF very well, the colors were tinted. I downloaded the newest DCRAW and hacked together this script and it works great.. doing 8 bit TIFF on this one, but can add -6 to do 16 bit if I want..

Thanks for the tip on DCRAW, it doesnt output to DNG but I think 16bit TIFF should have the dynamic range I want for that frame to do good HDR.

Take care,
Andrew

I am also looking at HDRTOOLS to exposure fusion the resulting TIFFs...
http://ttic.uchicago.e​du/~cotter/projects/hd​r_tools/

It seems like you might want to use the “-4” flag to create a linear 16-bit tiff for these tools.

Kirk

kirkt wrote in post #18525127
It seems like you might want to use the “-4” flag to create a linear 16-bit tiff for these tools.

Kirk

I will look into that flag, thanks!

ShutterKlick wrote in post #18524868
Dear friends,
I am running Windows7, and am looking for a command line utility to
modify the DNG's exposure and save to a new DNG, with the intent of
prepping for HDR processing.

For example, to make -2 and +2 EV modifications, Id like to do something such as:

...............

As I understand it, this process won't make any difference to your end procuct. Tonemapping the original DNG will produce exactly the same result. Think about it, the RAW file contains a dynamio range of at least 4 EVs in the first place. An HDR app will "see" this range and make use of it. Creating +2 and -2EVs so that you can feed 3 images into your app will make no difference.

Stiga wrote in post #18525214
As I understand it, this process won't make any difference to your end procuct. Tonemapping the original DNG will produce exactly the same result. Think about it, the RAW file contains a dynamio range of at least 4 EVs in the first place. An HDR app will "see" this range and make use of it. Creating +2 and -2EVs so that you can feed 3 images into your app will make no difference.

Makes perfect sense, thanks for the follow up!!

SNS-HDR Lite will take a single RAW and do a fine job as I found, but since I started this project.. Ive discovered Nik collection for PS, and WOW.. it does a fantastic job, results do not look fake at all, VERY REAL.. the results that Nik yields are the results I have been in quest for! Now, Photomatix and Machinery do a fine job too.... its hard to describe, but the results Nik gives is to my eye more pleasing..

Thanks all!
Andrew

Oh yeah, quick follow up.. the image created by HDRTOOLS is less than stellar, abandoned.

Andrew