Re: Dynamic Range Measurment
Hi Divo - Welcome to CiC. I've never worked out how Photomatix comes up with its DR numbers and now tend to ignore them. However, at one time I thought that getting the greatest value in Photomatix terms was the ideal. But, that is not the case. There is software called Picturenaut (Google the name to find it) that is free and arguably as good as Photomatix. However, during its calculations it displays the dynamic range of the HDR image. These calculations, expressed in Ev, do appear to be reliable or at least consistent. One problem with estimating DR in all HDR software is that the calculations are dependent on the precise algorithms used to combine images.
Cheers
David
Re: Dynamic Range Measurment
I use two methods to measure the dynamic range of a scene:
-Using the program Histogrammar by Guillermo Luijk (photo tiff from a RAW with a neutral revealed , but has the disadvantage of having to use a PC to check, which is not very effective)
-Measure with spot metering the highest light of the scene,
then measure with spot metering to the area of the scene with less light in which we want to get detail.
The difference in EV between the two areas define the dynamic range of our scene
Re: Dynamic Range Measurment
Thank you very much for replies!
@David
Picturenaut is doing well with merged RAWs but in case of single shot it does not show DR at all :(
@alvarito
Interpreting Histogrammar numbers is little bit incomprehensible for me. I've take my +0EV RAW to DCRAW and processed like C:\dcraw>dcraw -D -d -r 1 1 1 1 -4 -T -t 0 IMG_2563.CR2 Then loaded it into Histogrammar and saw this
http://i44.tinypic.com/122evqe.jpg
How to determinate DR since it says RGB: 65535 (100% of available), range [0..65534] to almost every tiff I load into it?
Re: Dynamic Range Measurment
Gui told me to reveal a totally neutral RAW file I have to apply the following command:
dcraw-v-r 1 1 1 1-o-g 0 -4 2.2 0-T filename
Moreover, the interpretation of dynamic range in EV measure it, much more intuitive
for the photographer that a relationship of brightness as you said.
In the photo you post, the dynamic range reaches 15 EV as I can see in the screenshot that you have put.
sorry, but my English is very bad
Re: Dynamic Range Measurment
Quote:
Gui told me to reveal a totally neutral RAW
By neutral RAW you mean normally exposed (+0EV)?
Quote:
dcraw-v-r 1 1 1 1-o-g 0 -4 2.2 0-T filename
This command returned: Non-numeric argument to "-g".
Quote:
much more intuitive for the photographer that a relationship of brightness as you said
It doesn't matter for me to get data in EV or contrast ratio, because it can be easily calculated, but exact number would be preferable than interpreting histogram.
Re: Dynamic Range Measurment
Quote:
By neutral RAW you mean normally exposed (+0EV)?
histogram a picture attached to the right but not burn
Quote:
This command returned: Non-numeric argument to "-g"
-V: display info during development
-R 1 1 1 1: white balance canceled
-O : no conversion to output color profile (to open in PS must assign a profile, eg Adobe RGB, the colors really will not make much sense)
-4 -g 2.2: gamma 2.2
-T: TIFF output
Quote:
It doesn't matter for me to get data in EV or contrast ratio, because it can be easily calculated, but exact number would be preferable than interpreting histogram.
Sorry, but my knowledge of the subject do not give more, maybe if you ask the GUI directly, he'll be able to respond
regards
Re: Dynamic Range Measurment
Is there a minor typo here that means there should be a space in front of "-g"?
e.g. dcraw-v-r 1 1 1 1-o -g 0 -4 2.2 0-T filename
I'm only guessing though
Re: Dynamic Range Measurment
then I copied the text as it sent me GUI therefore should be well
Re: Dynamic Range Measurment
I'm probably very late to this thread, but anyway wanted to correct the DCRAW commands seen here, none of which seems to be correct. DCRAW is a command line program, so syntax (including spaces and upper/lower case) must be fully respected.
To obtain a EV distribution histogram to find out real scene's dynamic range (only subject to sensor's linearity errors) using Histogrammar, there are two ways:
1. NEUTRAL RAW DEVELOPMENT (this is simpler and probably as good as the other method)
dcraw -v -r 1 1 1 1 -o 0 -4 -T file.cr2
The resulting TIFF will be opened in Histogrammar setting the gamma slider to 1, and switching to Log display mode.
2. RAW EXTRACTION WITH WHITE AND BLACK POINT ADJUSTMENT (this is strictly what the sensor managed to capture)
dcraw -v -d -r 1 1 1 1 -4 -T -t 0 file.cr2
The resulting TIFF will be opened in Histogrammar setting the gamma slider to 1.0, switching to RAW mode, and switching to Log display mode.
If your sensor doesn't have and RGGB bayer pattern, some channels will appear interchanged. Check the other 3 possibilities in the coloured icons.
Regards
Re: Dynamic Range Measurment
Guillermo -- is this really you? :)
Seems like forever since we've seen you here!
How's everything going?
Re: Dynamic Range Measurment
Very busy at work, it was my hard first year in a new job, new company, new sector, new boss. Hope this year things will be easier and I'll have more energies for photographing.
BTW I have bought a M4/3 PEN and cheap vintage lenses on eBay, having a lot of fun with the new stuff (despite its crappy sensor). Some test shots I did this morning in the Reina Sofia museum:
http://backup.cambridgeincolour.com/...464/museor.jpg
http://img814.imageshack.us/img814/9712/reloj.jpg
http://backup.cambridgeincolour.com/...2/pasilloy.jpg
http://backup.cambridgeincolour.com/.../3824/obra.jpg
http://backup.cambridgeincolour.com/...658/teatro.jpg
Regards