@gandalf3 Seriously waiting for you to scheme up a way to make smoke paint like ink. I know you can do it from that demo.

I've got some stuff baking right now actually

Everyone here, can we please put an end to the madness of folks not understanding alpha and the critical differences between the two formats (and how f*cked up and broken much of Blender's handling is) and go read Porter Duff? keithp.com/~keithp/porterduff/p253-porter.pdf

Seriously, there are two bits of history regarding alpha all imagers should know. First, that Alvy Ray Smith invented it (and he invented associated (premultiplied)) and that Porter Duff covered the basics of application, including discussion of luminescent pixels using associated (premultiplied) alpha.

@troy_s I am not even surprised you went on chat to mock people behind their back - shows only what type of person you are. I hope you gained a lot of street cred..

@troy_s You mock other people's solutions, when they work how they should work and they work reliably, only because you want done it your way. NEVER be blind to other solutions and never dismiss them, as they may have their place which you only don't understand. Your thinking is low.

@troy_s And regarding my problems with your answer you didn't address it to this point. Blender is broken, most of software is broken, your answer only works in a theory in a perfect world. I don't care it is by Smith or Duff or else, if the reality is different. Not even Blender handles Alpha like it should. Before calling people stupid and uneducated (you do this a lot), consider that maybe you are just ranting and causing unnecessary tension.

@Jerryno Your whole ceaseless and ever shifting vantage is painful as a cup of fsck. You clearly, from your other answer, didn't understand alpha. That is absolutely fine. But carrying on like a willfully stubborn child is, rightly so, something to be chastised.

@Jerryno This isn't a "perfect world", but rather people imaging in a specific context. Again though, it is so clear that where you should have stopped and shut up and said I didn't know that, instead you carried on endlessly shifting your bull*hit vantage.

So grow up. Way too old to listen to the archetypal idiot Libre / OSS buffoon prattling on with misinformation and delusional crap.

@Jerryno Blender certainly has broken elements

Guess why they end up that way? Same crap behaviour from developers that insist they know better. Guess who has been trying to get alpha fixed in Blender for about a decade?

Why doesn't it get fixed?

So the answer, as I said in the very first post is, as an imager, you have an obligation to learn about alpha instead of running around "I am right I know how alpha works". The more imagers that know this fundamentally rudimentary aspect of alpha, the greater chance broken crap software gets fixed.

So suck it up and grow up.

@Jerryno "You do this a lot" laughable crap. I don't call people stupid. Your current ignorant behavior is certainly uneducated, and certainly warranting a scolding for being so utterly last-word-I-am-not-listening-I-am-right-right-right. You aren't right. Your opinion isn't equal.

@troy_s I saw your answer as incomplete. Incomplete because there are many problems with alpha in the real world that you didn't mention and I pointed out (and now you finally acknowledged at last! - I don't blame you that Blender is broken btw.). So I wrote an answer that goes around alpha and is able to do emisive compositing of fire, flare, etc. XOR occlusion compositing of smoke, etc.

@troy_s i.sstatic.net/blxuv.png That answer is without a fault, it works very nicely with transparency and most importantly everywhere - it is widely used and used by much greater people than you and me. You are very closed minded to say the way is not right and I am stupid.

@troy_s You are entitled to think about a person what you want. But in no circumstance you go on chat mock someone, in no circumstance you go and rant about how an answer is not "according to Duff and Smith" and how "wrong" it is and actually failing to point out anything wrong about it. Maybe it pleases you to pick on incorrect words and maybe it pleases you to call other uneducated without knowing. I said I used incorrect messed terminology already, dont know what your point is.

@troy_s You know what this is all stupid, if you are the smartest go fix all the software and file formats, would you. Then I will delete my answer, because it will become unnecessary and cumbersome and I will use your answer everywhere. Happy?

@Jerryno Hey... Do me a favor, go read the most VES Handbook or Brinkman's compositing basics book. Guess what? You won't find any hacky node chains. You will find a discussion as to how light works and how to composite, using industry standard alpha.

Use EXR. Done.

Now enough with you. Grow the fsck up.

@Jerryno Also, words have meaning. Sorry about that.

So again, grow the fsck up.

Enough of this. Don't reply. No really. Don't.

@troy_s Ok then, I have just random friendly request as you are so educated and grown up. I want to render this i.sstatic.net/jufnI.jpg in cycles directly as additive emission. Without adding anything to the pipeline, without any file conversions or re-saves. And careful not to use my "hacky" node chain.

@troy_s I deal with people like you on daily basis. My experience is when cornered they tend to just irrationally swear and abuse.

Have a lovely day.

@Jerryno As I said. Use associated alpha and EXR, as you should be using a scene referred renderer.

It really is that simple.

In a post production pipeline, within the pipeline, OpenEXR is by far the most absolutely mandatory bare minimum requirement.

And also as I actually explained in the answer, if you analyse only the RGB components, you will see that they are emissions. That is, they range from zero emission corresponding with zero encoded value, to any arbitrary scene referred value.

So that means for a real muzzle flash, the hottest values near the core might be four to five stops or more above your middle grey. 0.18, which would be 0.36, 0.72, 0.144, 2.88 or 5.6 for an emission value.

Scaled by occlusion, with remainder as pure unoccluded emission.

Those values are how new engines work as well, including Assassin's Creed's engine, Far Cry, etc. They all render in the scene referred domain now.

@troy_s Sometimes I use EXR, sometimes I use the "hacky" trick. It depends on target application and on the task. It is good to have and know all the tricks and it is wrong to bash one of the tricks as incorrect.

@troy_s Hold on I know what HDR is, it is another topic

It isn't.

It is part of the same topic, and it isn't HDR

I bet my terminology is incorrect. So 16bit or 32bit.

Bit depth doesn't matter.

(In the discussion)

TIFFs can encode 16 bit, but they could be display referred or scene referred. As could DPX.

How are you gonna save that value that is more than 1 then?

See my point? :)

I wasn't just randomly spitting up sentences to win SE points.

There is a very good series of reasons that certain file formats are exclusively used in imaging circles. PNG for example, has no penetration beyond web largely because of the Alpha issue.

But EXR can do an imager no wrong as advice. It stores many potential planes, stores appropriate aloha, stores scene referred, display referred, and data formats normalized and other with ease, etc.

Working with float values outside of clip range makes perfect sense to use EXR or similar. And EXR is a very nice format, like it a lot. But also adding those channels my way on 32bit images will work, the emission will end up correct. The only case when my answer won't work is emission+occlusion at same time or to have dark colors with 100% occlusion - like a grey object on black. The occlusion part of my method is mostly useful just for smoke.

Anyways, I would like to have a shot at your (and cegaton's) questions on the weekend. It is a good and challenging topic.

There is no but.

Everything before the but is a lie.

If you spent the time you tried to attempt an addition node structure into proper alpha, you would ha e solved it.

And before I answer, do you really want me to answer regarding dark colours? I will give you a hint, it is wrong as well.

@Jerryno I could demonstrate in two seconds with an associated alpha image over a rainbow, but it has been demonstrated thousands of times.

Google Zap Anderssen in the infamous Adobe thread. Google Larry Fritz's explanations or Jeremy Selan's.

All of this is basic common knowledge in imaging circles, and it is not a sin to not know it or understand it or understand the principles. What is absolutely unforgivable is to perpetuate misinformation.

It cripples people.

So again, please just stop before leaping to yet another mistaken answer or trying to make your point; it simply reveals how vast the depth of your misunderstanding is.

If you would like, I can explain it, but I won't tolerate it if you keep being adversarial and implying that somehow this is just opinion and that your advice is valid.

So peace.