darktable ep 137 - The Sigmoid Primaries panel

[@luisarevalo6112]

Videos 137 & 136 are great for several reason besides well done! 1st I finally update darktable to 4.6 after much hesitation. 2nd Learned how helpful these models are to what I do and 3rd I can now make better B&W conversions with deeper tonality! Thank you for these great videos!

[@audio2u]

My pleasure! Glad they've been helpful.

[@lionhawk555]

My inuition is that sliding Red attenuation to the right would increase the attenuation in the red channel. Seems straight forward to me.

[@audio2u]

Yes, I get that! 😀 But if you are turning something DOWN, my brain says you should be moving the slider to the left, not to the right. Not a huge deal, just the way my brain works, I guess.

[@simonmeeds1886]

@@audio2u Hitting the brakes harder isn't the same as taking your foot off the accelerator. I keep thinking of it like squelch on a radio transceiver - something I haven't thought of for a very long time. To be fair to everyone, it's just the way flannelhead has thought of it. There is always a risk that a developer is too close to something to think of the general user, but I'd say he has it about right here.

[@audio2u]

Fair enough!

[@g.t.m.thurlings4882]

Thanks Bruce, I am learning much from you!

[@audio2u]

Glad to hear it!

[@andymcgarty3099]

Really excellent video. I seem to be using sigmoid more and more, so this is well timed.

[@audio2u]

Glad to hear it!

[@shamanbeartwo3819]

I have the same monitor and love it. B&H Photo had an article on monitors specifically for photography (versus gaming) and this was their top choice...unless you wanted to spend $3,000. And even then they felt that unless you were a full-time professional film editor save the money and buy a new lens instead.

[@audio2u]

Nice! 4 months in (or however long it has been) and I'm loving it!

[@GaryParris]

i would say it's the correct way around because of you want the least attenuation for most images and to move it to the right is turning down and add purity back. it seems pretty correct in my understanding but hey it's probably just a preferential thing for most people as long as you know why and where to use it that's really all that matters :O)

[@audio2u]

Exactly! As long as you know what it does, anyone can learn to drive a car with the steering wheel on the wrong side!

[@Zuzzt]

Did you know that when you open a new instance of a module and right click in the field where you could give it a name, there is a list of presets for that module.

[@audio2u]

Hmmm.... not sure. I'll have to check that when I get home!

[@knownas6217]

The slider issue intrigued me. My thoughts went like this. If we consider how in western cultures we learn to scan literature, it's left to right. It then becomes instinctive for other activities were an action may be required. However there are exception the volume dial is one, to turn volume down we turn to the left and to the right to turn volume up. With repetition the becomes the accepted norm. Thus for those like yourself it feels counter intuitive to move something to the right to reduce it. A Final thought how would we set this sigmoid RGB module's sliders if they where to aline vertically?

[@audio2u]

If the sliders for attenuation were vertical, I would HOPE they would start at the top, and you would drag the slider downward to attenuate. That's the way my brain works, anyway! :)

[@knownas6217]

@@audio2u so would I

[@deansonneborn7134]

You really explained this primaries module well. Have you ever thought about doing an episode on the printing module? I keep checking on the tube for this subject but there does not seem to be anything!

[@audio2u]

I will get to that eventually!

[@matthewharrison3813]

Thanks for the video! Do you have any videos covering the basics of the sigmod module?

[@audio2u]

I THINK I covered it when it was first introduced. You might need to search, but it would be after episode 110 if it's there.

[@Eigil_Skovgaard]

Thank you, Bruce. Welcome update to my understanding. The only thing that confuses me now is - that only one Recover purity slider exists. Even though I can't find an image with two extremely saturated colors here and now - I would imagine they existed in the same image - even all tree colors together. Then the Recover purity slider - as far as I can see - would have to represent a compromise between the recovery of two or three colors? Or is the idea that only one extreme color is managed per instance of Sigmoid - and more instances take care of the next colors?

[@audio2u]

I've wondered the same thing. I think the recovery slider operates across all colour channels simultaneously, but it won't allow any channel to get pushed beyond legal limits. So if you've salvaged say the red and the blue channel, but green was ok, then the recovery slider will try and bring back the intensity of the red and blue channels, but leave the green untouched. That's my understanding of it, anyway.

[@Eigil_Skovgaard]

@@audio2u That would be an intelligent mechanism. Let's hope it is.

[@simonmeeds1886]

If you were manipulating more than one colour wouldn't you want to use masks, and if you did that you would almost certainly need more than one instance of sigmoid. In fact I'm wondering whether in practice you would want to use masks with this operation anyway or does it only operate on out of gamut areas in the specified colour and leave everything else totally unchanged? If that's the case don't you have problems with lack of feathering?

[@audio2u]

Yeah, I'm thinking masks and multiple sigmoid modules could certainly help in this scenario. And yes, my understanding is that the recovery slider will only push colour channels to the limit of gamut clipping, but no further.

[@mr.matt.eastwood]

Hey Bruce, what tool are you using to display key and mouse button presses? I've only been able to find Screenkey and it's serviceable, but this looks so much better!

[@audio2u]

It's a linux app called keymon.

[@mr.matt.eastwood]

@@audio2u Love it, thanks! Works like a charm.

[@ryanstark2350]

I have a really old Eizo monitor and a slightly newer one but both are old. They still beat most newer 4k monitors unless I spend a fortune, unfortunately.

[@audio2u]

Yep, I'd believe that. I'm very happy with my proart monitor though.

[@ryanstark2350]

@@audio2u I had a look at that monitor. Not that expensive. I'll have to move to 4k at some time. Photography is a very expensive hobby and then it gets even worse with video. The cameras are actually not that expensive. They have all been good for a while now. It's all the periphery stuff.

[@audio2u]

Totally agree!! :)

[@petevonschondorf4609]

as a 70+ year old dyslexic left hander, the left - right slider direction is generally backwards for me regardless of application or instance. So your confusion/brain warp around slider direction, although understandable, has been a problem for me, forever.

[@audio2u]

Haha. Fair enough! I guess it all comes down to how each of our brains is wired, right? 😃

[@mtlc-eu]

Hello Bruce, thanks for your good videos here. Speed, details and quality are just perfect. I fully understand the irritation about attentuation and slider direction. You could only circumvent this with a slider from left to right with 0 to 100 % and the slider text like "red amplification". In this case the initial starting point would be 100 % to the right. The issue can be really compared with the brake vs accelerator pedal in cars. BTW, with rotating knobs it is even worse. E.g. some navigation systems in cars zoom-in when rotating counterclockwise, in other cars they zoom-in when rotating clockwise. I find the clockwise more intuitive, because it is like a screw which goes nearer to the object, when you turn clockwise. But some car manufacturers do see this different.

[@audio2u]

As I mentioned in my video, my brain thinks "attenuation" as turning something down. Hence why, to my mind, the value should be zero % at the right hand end, and 100% at the left hand end, with the slider beginning at the right side. But, maybe that's just me... :)