Histogrammar V1.0

[John Sheehy]

Some people claim that they see a difference in the highlights but have produced no convincing demonstration confirming their claims.[a href=\"index.php?act=findpost&pid=127654\"][{POST_SNAPBACK}][/a]

Does the Nikon software convert uncompressed NEFs to compressed?  If so, you can take an uncompressed shot with smooth gradients in the highlights, and make a copy compressed, and zoom into them levels-wise (with blackpoint and whitepoint) to see how extreme you need to go to see a difference.

Leica M8 RAWs actually use less levels.  They use 256 levels (8 bit) with a LUT, using a curve that preserves levels from the shadows better than from the highlights.

[Guillermo Luijk]

I did a conversion with Nikon Capture NX and noted the same behavior as with ACR. I also did a conversion with RawMagick, which is a well regarded converter that uses floating point math rather than integers.

Here is the shadow portion of the histogram:
[attachment=2804:attachment]

and towards the midportion:
[attachment=2805:attachment]

The missing spaces on the left are present, but irregularly spaced. It could be that they were filled in in the linear file, but the holes appeared during the gamma correction as you predict.

With Histogrammar we see all types of things that were not apparent in low resolution histograms.

Bill
[a href=\"index.php?act=findpost&pid=127654\"][{POST_SNAPBACK}][/a]

I think I have just found the reason for the discrepancy (peaks in DCRAW, no peaks rest of RAW developers). The key is colour profile conversion: -o 0 option in DCRAW develops with no colour profile conversion (as far as I know: just black offset substracting, WB, 0..4095 range adjust, and Bayer demosaicing). But commercial developers additionally always convert to an output colour profile (sRGB, AdobeRGB...).

We previously saw the peaks in DCRAW's developing with no colour conversion.
This is what we get in DCRAW linear with sRGB colour profile conversion (-o 1):


No peaks (and Zoom=1), the colour profile conversion reallocates all levels in a very uniform way, making the original captured and interpolated values absolutely indistinguishable (this word exists?). By applying gamma over this last histogram we would get a similar result as in ACR and Capture NX: locally-equally spaced matching RGB levels of similar amplitude.

BTW I wanted to ask you something that disturbs me a bit: I almost have no idea about colour profiles, but as far as I know each colour profile (sRGB, AdobeRGB...) has its own standard gamma curve. On the other hand DCRAW allows to develop a RAW file and convert it to a given colour profile, but IN LINEAR MODE, i.e. not applying the gamma correction yet.

Is this conceptually correct? can the gamma curve be applied after a linear colour profile conversion as a separate stage of the conversion process?

David Coffin (author of DCRAW) told me he puts in the output TIFF file converted to a colour profile the needed information so that for instance PS recognizes it as a linear (still gamma=1.0) image. And it seems so: when you load this tiff files into PS (indicating it is gamma=1.0 in the Edit->Colour adjust->RGB custom menu), and then you convert to a colour profile (which can even be the same that we previously set in DCRAW), PS clearly expands the histogram by a gamma curve.
What I wonder is if all this process is correct from the perspective of getting a correctly developed image or we are just getting "numbers" that in some way look like what our photograph should have been.

Regards.

[Guillermo Luijk]

I have just uploaded Histogrammar v1.1 ready for download ("DESCARGAR HISTOGRAMMAR V1.1").
It includes several new features, the most remarkable of which is the possibility to analyse the Zone System of the scene, plotting each f-stop area in 16 greyscale tones (blown areas are plotted red, and black areas in blue).
To obtain a correct result linear RAW developing must be applied (e.g. using DCRAW).

For this escene:




This is the real f-stop distribution (every grey colour means double/half amount of light as the previous/next one):





There is also a Histogrammar tutorial (Spanish).

[EricWHiss]

Hi Guillermo,
Thanks for your efforts and for sharing this program with us.  It looks like it could be really useful.
Regards,
Eric

[Guillermo Luijk]

I have added a possibility to plot the classical Ansel Adams Zone System, consisting in only the top 9 f-stops represented in the expanded 16 f-stops Zone System I previously showed.

Both ends are pure white and black, and are supposed to contain no detail at all (this is however not true as with high dynamic range techniques as multiexposition we can achieve easily more than 9 f-stops full of information).

[Guillermo Luijk]

I have just uploaded Histogrammar v1.2. It has 2 new features I find interesting:

1. A gamma slider so by setting the appropiate gamma of the image under analysis, now the logarithmic histograms (i.e. histograms representing EV) are correct even with non-linear images as before. So you can develop your image neutrally (all settings to 0) in ACR/LR or any other RAW developer, and the log mode, EV division and zones will show the dynamic range of the scene in the correct f-stops.
NOTE that the user must set the appropiate gamma (2.2 in Adobe RGB, 1.8 in ProPhoto RGB), the programs doesn't do that automatically.


gamma was set at 2.2 (default) in this Adobe RGB image, so now the log histograms and EV divisions are correct.


2. It has a new 'RAW' mode which allows to plot 100% RAW histograms (useful to calculate saturation points, black points, find fake ISOs,...). To do that you just need to extract the RAW data with DCRAW:
dcraw -D -T -4 -t 0 file.cr2 provides pure RAW data, with the same values as it was codified. Useful to study unprocessed RAW values.
dcraw -d -r 1 1 1 1 -T -4 -t 0 file.cr2 provides undemosaiced data but corrected by the black and saturation points and scaled to 16-bit. Useful to look at the log histograms.




For those who have already installed Histogrammar v1.1 don't uninstall it, just download the v1.2 update (60 KB) and replace the .exe file as indicated in the .txt file
For those who don't have Histogrammar installed, download and install first Histogrammar v1.1, and the proceed to update the .exe file.

Download both files from HERE.

Any feedback is appreciated.

BR

[Hening Bettermann]

Hi Guillermo!

I am preparing for ZeroNoise, and hence for dcraw. Spoiled by the Mac user surface, I find myself struggling not only with Windows, but with Unix!

I have found invaluable help in a real basic tutorial for Unix (on the Mac) here:
http://mrox.net/blog/category/learning-the-terminal/

and equally invaluable help to install that f... DLL file here:
http://www.computing.net/answers/programmi...fmtdll/540.html

Studying your equally invaluable :-) dcraw tutorial, I understand that the first thing I need to do is determine the saturation point of the camera.

Her is the attempt on the Nikon D200, but 2 different Fujis and the 5D2 exhibited the same problem.

This is the overexposed file (if not by 4 f-stops, this was shot before I knew about ZeroNoise).The NEF opened in Rawnalyze shows this histogram:

[attachment=12163:151.NEF_in_Rawn.jpg]

The linear TIFF, resulting from dcraw -v -D -T -4 and opened in Histogrammar 1.2, where I hoped to find the saturation point specified, looks like this:

[attachment=12164:151_3.ti..._His_1.2.jpg]

The histogram shows levels only in the utmost left end and is then clipped, not fading out; and even though "Plot labels" is selected, there are labels at 0 and 65 535, but not at the clipping level. (And btw the Zones do not show up).

Something is wrong - but what??

Kind regards - Hening.

[Guillermo Luijk]

Something is wrong - but what??

Nothing is wrong, simply you didn't zoom IN the histogram.

In the status window you can see sat point for R is 4095, G is 4020 and B is 4095.
The histogram displays at opening Histogrammar the whole 0..65535 range, so values such as 4095 are obviously plotted to the left.
Just click + in ZoomX several times and you will get any degree of detail you may wish (up to zoom 100%).

BR

PS: I have just added a new feature, now when you move over the histogram the cursor changes to a cross and a label up the histogram indicates which exact level is under the cross, so you can find out accurate sat points:

[Luis Argerich]

I was using 1.1 but somehow it says it has "expired" what kind of licensing does Histogrammar really use? Why can't I just keep using what I was using without downloading anything.

Luigi

[teddillard]

so THAT's how you make those awesome histos.  SWEET!

...not for Mac, though?

[Guillermo Luijk]

I was using 1.1 but somehow it says it has "expired" what kind of licensing does Histogrammar really use? Why can't I just keep using what I was using without downloading anything.

I don't know about licenses, I guess this program should be considered freeware?.
I chose to put an expiration date just because I like to keep track of the real users of the program. However any old version works if you set any date on your PC prior to expiration.

...not for Mac, though?

With Parallels it works fine!

BR

[teddillard]

With Parallels it works fine!

BR

oh that's cold.