Interestingly, some major photo competitions require 'original' RAW files to be submitted along with processed jpegs. The idea is that they can check that the image hasn't been modified in a way that breaks the rules.
Of course, software people know that it would be tedious but technically straightforward to concoct a fake RAW file from another 'raw' format such as a PPM image. The stakes in these competitions can be quite high so it's a bit disconcerting that they rely on a presumption that converting RAW files to editable images is a one-way process.
No - it's not straightforward. How the light strikes, sensor imperfections, patterns unique to each camera body even, thermal noise. It's very very hard actually. It's one thing to doctor a finished image - it's another, in a forensic level really, to doctor a RAW file. You can make one which on its own is syntactically correct but which does not show all the telltale signs of being shot in actual hardware, no patterns or imperfections etc. This is trivial.
Next level is to make it look plausible on its own, with plausible imperfections. This is a bit more involved and tedious.
The really hard part is to make it look like it came from the exact same individual purported camera body the photographer allegedly used. This is really hard.
An analogy would perhaps be taking a picture of a room:
Now, build another room that would make the same picture. Make sure everything in the room is plausible yet renders exactly the same picture as the first room. (The room is the RAW file.)
Edit:
(I'm not saying all the competitions have the time and know how to verify a RAW file.)
Couldn't you just take whatever image you want to convert to a RAW file, make a really large high quality print out of it, and then take a picture of that? I would imagine that with the right lighting setup (and a really high quality printout) it would be pretty hard to tell that it is a picture of a picture.
Nope. Light is a 5D wavefront. Each x,y,z of origin in the real world is actually a sum of photons from many directions, scattering to many other directions. So you have two angular components. At times, phase matters too, and frequency, so each photon needs perhaps 7 parameters to capture its state, (x,y,z,θ,φ,ψ,λ).
On top of that, you have diffraction effects in the optics, chromtic aberration, and even some birefringence effects.
Algorithms exist which can detect if an image has been cropped, and what region of the original it came from. I'll leave as an exercise to the reader how that works :) hint: keyword is "media forensics"
The scenario I'm talking about is not synthesising a RAW file from scratch, but being able to freely edit it and save the result back into a RAW file that looks "original". I don't think you've made any statements that indicate that doing that would be complex.
Again, this is not about faking a RAW file from scratch, just being able to edit it in place.
One potential complication just occurred to me. If, (IFF!) each sensor site has a somewhat unique non-linearity in any way, you can't just go around in the image and change "pixels". You have to adjust them in a way that would not change the patterns normal to that camera for that sensor site and for neighboring sensor sites which could have been affected by the same light.
Competitions, when an image is contested, sometimes ask for images made before and after the winning image. If it isn't a studio image, the time-series is hard to fake.
Just the other day someone posted something here about defunctionalizing continuations. That's the way to go: whatever amount of state the server has to hold, you have to hold anyway, and clever defunctionalization will let you just hold that amount even with a continuation-based approach.
The concept of continuations is well-established and they have their uses. They have been part of the landscape for years. They can be confusing, and that's impossible to separate from their power.
The inversion of control that this paper is talking about is the way an application running on a webserver typically gets called by the browser rather than the other way around. Continuation-based webservers reverse this inversion and create an illusion of continuity of control flow on the server side. The application is suspended when a page is sent to the browser and resumed (via a continuation) when the response arrives. So this is about permitting server-side applications to be written in a nicer style as far as control flow is concerned.
I think you are getting downvoted because your comment more or less says that you don't know much about the background, and haven't read and understood the paper, but are inclined to dismiss it anyway.
This comment is like a red rag to a bull for me, because why wouldn't some artists want a basic grasp of calculus?
Bear in mind that a secondary education, for most people, involves learning the basics of calculus. You might be thinking that all artists are bad at math or too stupid to grasp calculus. You might be thinking that there are no applications of calculus in art. I don't know. But given the role artists are supposed to play in society, it seems pretty reasonable to expect that some of them will have an interest in learning calculus to a high school level like a significant fraction of the non-specialist public.
A concrete example of this might be an artist who is interested in systems theory from an ecological perspective. Once you start talking about stocks and flows (of fish or minerals or greenhouse gases) then calculus and differential equations are really the next thing to tackle.
I interpreted the vague "Artists?" very differently from you. I thought it was saying "What about this makes it appropriate for artists? It is not showing off the beauty and simplicity of Calculus."
> You might be thinking that all artists are bad at math or too stupid to grasp calculus
I think labeling it as "for Beginners and Artists" is actually doing some of that. I certainly would not make a book labeled for artists unless I thought it would be particularly good for artists and from what I have seen this book does not touch on creativity or beauty. Therefore it must be labeled as for Artists because they can't learn calculus from existing books which might imply
"all artists are bad at math or too stupid to grasp calculus".
I don't know the Observable folks personally, but I've been watching what they post on Twitter. It's not snobbery to say that the level of polish and sophistication present in what they put out (in terms of the reactive architecture and the graphic side of it) is second to none. Their product has got so much class that the idea that they would spend time on SEO is kind of incongruous, right?
I know more about how this works in the arts, where the relevant term is "residency". Access to exclusive residencies is usually allocated on the basis of previous career success, and they are usually funded by endowments of some kind. It's an example of institutional support for artists, and the top residencies are extremely elitist. There are lots of humble ones too, though.
Of course, software people know that it would be tedious but technically straightforward to concoct a fake RAW file from another 'raw' format such as a PPM image. The stakes in these competitions can be quite high so it's a bit disconcerting that they rely on a presumption that converting RAW files to editable images is a one-way process.