Online Tool for curve plotting and analyzation

[reneboehmer]

Yesterday, while working on my tonal reproduction tool, I had the idea to make an online plotter for anyone who wants to plot their curves quick and easy. With this free, online tool, you can just input the 21-Step tablet Density measurements you made. The Tool will assume 0,15 log H steps. It is meant to be used with relative testing, this means you don't know the (luxs) exposure intensity that was used to expose the different densities. You can assign one curve (the one you developed for box speed) to your reference and enter the speed. Based on this, my tool will calculate the relative speed for each curve. It also shows the contrast index or gamma of the curve. (Contrast index is similar to gamma but takes another way to calculate curve form). You can also enter ISO R or LER in a field with some tolerances, and my tool will show you what curve to use for which paper. I also included a Flare slider, which will add a haze over the data that is more active in the shadows. (This is done because Camera systems and Optics don't transfer scene illuminances without distorting them.) You can export all your data in a somewhat nice PDF. I am still working actively on my tools, so take everything with a grain of salt.

https://analogworkshops.at/plotter.html

This is the website. Feel free to have fun with it and test it. I would again be very happy with some feedback!
Hope this helps someone!

All the best! René

 

[chromemax]

Bravo! A great job.

 

[ic-racer]

How are you calculating ISO, Gamma and CI?

 

[reneboehmer]

Iso

How are you calculating ISO, Gamma and CI?

ISO is relative to the reference curve you can input. Gamma is calculated with linear regression of the linear portion of the curve, you can even define end and starting point in the menu. Ci is the slope of a line connecting two points on the D-logE curve found by the intersection of the curve with two concentric arcs centered on the Dmin axis. The inner arc has a radius of 0.2 units, the outer has a radius of 2.2 units.

 

[reneboehmer]

How are you calculating ISO, Gamma and CI?

I also added a dynamic flare model which is based on the paper "What is normal" by @Stephen Benskin . It will adjust flare based on log scene luminance range. This means this flare model should be somewhat reliable and accurate. But you can also chose to turn flare off or add your own flare factor thats applied generally.

 

[reneboehmer]

This tool is only used for relative speeds. It assumes that he first curve you developed for "box speed" is accurate and hits the correct speed point for box speed ISO. Total measurements dont make sense in such a tool since almost nobody has a calibrated sensitometer at home.

 

[acrobatic_citron]

calibrated sensitometer at home.

Still waiting for someone to launch a kickstarter ha

How could I use for it say Foma which from the data sheet is never box speed

 

[reneboehmer]

Still waiting for someone to launch a kickstarter ha

How could I use for it say Foma which from the data sheet is never box speed

^^ ahha, yes, but I think it shouldn't be too complicated to make a DIY one. I've been toying with the idea for some time!

 

[reneboehmer]

This is the new interface of the tool I changed the function a little bit. It works like this, you choose the DR you want for your paper (LER), maybe 1.1. Based on this, the program will show you flare adjusted Subject luminance range values in f-stops for each curve. If you have multiple curves, this should cover almost all scenes you will face in reality.

The program will export a nice PDF that states how all the values were calculated and shows you all important values to work from directly.

 

[schyter]

great job!

 

[David R Williams]

Thank you very much for not only developing this, but also for sharing it with the community!

I'm in the process of performing a number of film/developer/speed/contrast tests and this will be invaluable.

Moderators: Can this be added to the "Resources" section so can be easily found in future?

 

[MattKing]

Moderators: Can this be added to the "Resources" section so can be easily found in future?

@reneboehmer - would you like us to move this there?

 

[reneboehmer]

@reneboehmer - would you like us to move this there?

Sure thing! I don't mind.

 

[reneboehmer]

The tool will now also plot these curves to sum up your data. The more data plots, the more precise this approximation curves become. The curves will help in working with the output data.

 

[MattKing]

Sure thing! I don't mind.

I'll see if I can move it.

 

[MattKing]

I'll see if I can move it.

And I seem to have succeeded. Please reach out if any problems arise from moving it.

 

[MattKing]

And I seem to have succeeded. Please reach out if any problems arise from moving it.

It seems there are problems trying to do this the easy way. I'll look to see if I can find another way to do it.

 

[reneboehmer]

Thank you very much for not only developing this, but also for sharing it with the community!

I'm in the process of performing a number of film/developer/speed/contrast tests and this will be invaluable.

Moderators: Can this be added to the "Resources" section so can be easily found in future?

I suggest taking the results with a grain of salt. I'm still working on it. But I would love to hear if you were successful in using it and the generated workflow.

 

[ic-racer]

I also added a dynamic flare model which is based on the paper "What is normal" by @Stephen Benskin . It will adjust flare based on log scene luminance range. This means this flare model should be somewhat reliable and accurate. But you can also chose to turn flare off or add your own flare factor thats applied generally.

So, Delta-X model?

 

[reneboehmer]

So, Delta-X model?

Yes, now it uses Delta X to determain relative speed

 

[Andrew O'Neill]

Very cool. Maybe you could incorporate Zone System into it.

 

[reneboehmer]

So, Delta-X model?

But flare is calculated at the exposure stage of the process, flare is not "chemical fog" on the curve. It is added to the LSLR and then SBR is modified based on flare intensity. Flare intensity, once again is based on the LSLR range. If a high contrast motive is photographed more flare will be simulated, if a low contrast scene is to be photographed a low flare factor is used.

Delta X model is only used to determine ISO speed, DeltaX takes the flare variable in the ISO norm into account yes, has in it self no real connection to the dynamic flare model though. Delta X is only used to get more accurate relative speed results.

 

[koraks]

Very cool. Maybe you could incorporate Zone System into it.

He has that, too. Check this out: https://analogworkshops.at/rechner.html

 

[reneboehmer]

He has that, too. Check this out: https://analogworkshops.at/rechner.html

Although, this is not an accurate tool and does not deliver accurate results. This is only for visualization and learning.

 

[Andrew O'Neill]

No, I mean instead of CI's, have a graph that shows N times.