Monochrome March

In lieu of banging my head against the wall trying to figure out how to get highlight recovery working, I decided to try adding monochrome functionality to Filmulator.

Thing is, I don’t know anything about monochrome conversion and how to do it well; I’ve always only shot color.

What are peoples’ preferred ways to convert to B&W, how do you want to control it?

Six hue-weight sliders? However darktable’s square thing works?

Let me know.

In rawproc, I use RGB sliders, which correspond to the percent contribution of the channel to the desaturation formula:

Desat = (R*Rpct + G*Gpct + B*Bpct) / 3.0

Then, I default the percents to the BT709 RGB coefficients, 0.21, 0.72, and 0.07, respectively.

Then, with the sliders, I can change the coefficients to represent different filtrations. For instance, you can dial in a plain average by setting each to 0.33. Or, do an extreme red filter with Rpct = 1.0 and the others - 0.0.

Simple, but flexible.

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As you may be well aware, there are many ways to go about making the image monochrome. There are

  • Purely mathematical strategies such as norms, etc.
  • Colour model and industry driven ones such as brightness, lightness, luma, etc., channels of colour spaces with various illuminants, of different standards and other concepts.
  • Blend and opacity driven ones that use mixers, curves, etc.
  • Or a combination of them.

There are also

  • Those with monochrome or colour effects which can be easily generated by CLUTs and other tools: film toning, fading, split toning. B&W film emulation and sepia are common examples (can’t think of more examples ATM).

When darktables monochrome modules gives good results, I prefer that, but I seem to only get good results half the time.

Lately I’ve been going with the channel mixer module, which is a technique I learned back in the Photoshop 5 days. It generally gives pleasing results, but is more work than the monochrome module.


What do you do with the channel mixer? Just control the relative proportions of red, green, and blue with the destination being the grayscale channel?

How often do you use negative coefficients? Is that something I could leave off without you missing?

What do you prefer?

In Filmulator I want whichever is the most streamlined and intuitive option that provides good results.

Yes, that is it.

I’ve never tried, but when all three sliders are at zero, the image is black. So I don’t know what I’m missing.

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Well with negative coefficients you can, for example, put red to 2 and green to -1 to make things that are slightly green even darker than just their red component would suggest.

I employ everything at my disposal. For simplicity, I would include the ability to map CLUTs, as they are essentially a one click solution for converting to monochrome and toned images. Of course, you can add other features, depending on how much you would like to incorporate.

Negative coefficients are useful. GIMP allows it.

PS example ratios:


GIMP example:

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And here’s my first monochrome conversion!

AppImage here if you’d like to try it: (until 2019-03-17)(edited)

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Got this, on Ubuntu 18.04:

glenn@caliente:~/Downloads$ ./Filmulator-git.2482387-x86_64.AppImage 
APPDIR: /tmp/.mount_FilmulOfS1xg
dbSetup old version: 10
loading UI from copy in appdir directory
QQmlApplicationEngine failed to load component
file:///tmp/.mount_FilmulOfS1xg/usr/qml/main.qml:78 Type Edit unavailable
file:///tmp/.mount_FilmulOfS1xg/usr/qml/Edit.qml:1 module "QtQuick" version 2.11 is not installed

Error: your root item has to be a Window

Do I need some Qt stuff?

Oh. I guess I hadn’t tested it yet. Let me see why I asked it to require Qt 5.11…

This one works.

It does! Neat software, will mess with it a bit now that I have an AppImage…

Regarding monochrome, Interesting the effect of multipliers that break the proportion of 1.0.

I think the multiplier tool is what gets you a basic monochrome, followed by aggressive contrast manipulation, of which monochrome is more tolerant than RGB…

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After a few more successful conversions, I’ve decided to merge this branch into dev.

All in all, I think this was a successful conclusion to my first Monochrome March.


Build for macOS 10.11+ (runs on Qt 5.11)


If the goal is to reproduce realistic BnW-Film Look, there’s one best practice, you should have a look at. I’m working 90% BnW and this is the last piece of proprietary Software I still have to use. It’s Grubba Software’s “TrueGrain”. All you’re asking about can be found there in perfection. They split the work in three Tabs: a) Spectral Response, b) Dynamic Range, c) Film Grain. a) and b) in Filmulator 'd be my wet dream :wink: So thanks for having a look. Btw. I’m not affiliated in any way. It’s just the best piece of software I could find/try in 20 yrs. Cheers from Germany, Helge

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If you’re looking for the ability to mimic specific films, I’m not sure that Filmulator is what you are looking for.

What Filmulator implements is stand development, letting you control the dynamic range via depletion of developer, because I believe that this effect which occurs mildly even in normal development is the underlying cause for people’s fondness of film.

Spectral response is out of scope, aside from the monochrome channel mixer, mainly because I intend to keep the user interface as simplified as possible. If you can still get the response you want, then that’s good, but in color output, Filmulator has color shifts towards primaries that might interfere with spectral response emulation by software downstream in your workflow.

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Well - hard to explain, as I am not so tech-savvy … It’s not important for me to mimic a specific film. One of the mainsteam BW films with their characteristics like Tri-X or HP5 would be sufficient for me. The other way round: What I tried is devloping raws in color with filmulator then do the transformation to BnW with TrueGrain. That worked great. It already spares me using Rawtherapee in combination with darktable to get the color devek right. So one software less. Would just be really nice for me to have it all in one Software and yours is very close to what I would need. Filmulator Output in BnW compared to the output I get this way nevertheless still is lightyears apart. I guess the main problem here is the contrast. The BnW Output of Filmulator looks really flat in comparison. - I know: not everyones mainstream usecase here. And again: Thanks for your great work!

If you want more of the harder shadows found in film instead of the flatter, high-dynamic-range look, the latest versions have the Shadow Rolloff Point slider. Raise that up and you’ll get a darker, high-contrast look similar to the toe in film.


(the bottom one has the slider maxxed out; if you want me to increase the upper threshold I can)