Semantic uses

[fredjeang]

Hi,

Apologyzer: This post, for its nature, could have been written in the "cofee corner". I thought however that it would fit better here. Aren't the correct language uses part of our technical knowledge? I do think so.

I realize that, for lack of knowledge, strictness, o simply the need to get shorter, I often use some words without being sure of their real meaning.
I also noticed that it does not happened just with the amateur, but also with very experimented professional photographers and in some photographical conversations we end using words and expression in a very vague way, sometimes even for fashionable reasons.
Digital age has introduced new techniques and languages, and I'm not sure we define precisely the concepts.

One of the best example is the technical and esthetical debate around digital/film - Noise/grain.
I find at the end everything very confusing. Hope this post could help.

-What is the real meaning of noise ? ( I understand it as polution ). To me, both digital and film have noise. But then, what's the real nature of this noise. Can we speak of "digital noise" different from "film noise"? If so, where resides the real nature of these differences. If there are two different animals, then we should use two words.

-What is exactly, the thing we call grain, film grain, paper grain. Does digital files have grain? Is grain only optical o physical?
I remember when I was working years ago with the T-Max 1600, pushed +1, it did have a lot of...what, grain? noise? both? If I ask myself the question I find that I'm not so sure what to use, neither how to describe properly the differences I can see with digital rendering.
When I do the same with my DSLR, what I see is "artifacts". There are much less plaisant to the eyes than with film, but does film have "artifacts"?

-Can pixels have different natures (geometry etc...)? Film does not have pixel, still it has "dots" no? How these "dots" are called? And they can be of a changing nature according to the emultion, developing etc...but we also develop our digital Raw files, so what?  

So, to come back in my example, in the debate between film and digital virtues, we always read the comments from the pro-film talking about the Film-grain-opposed-to-digital-noise and the film-artifact-free. But are these arguments really technicaly exact and perceptualy corrects?
We see a difference. When I look at some of my digital file 100% in C1, I'm not very happy at all about what I see. I must confess that it did not happened before with film. There was no sensation of "polution". So, the difference we see is real or simply imaginary? What are the right words to describe it?

Many questions as you see, but more an overall feeling of  


If you have more example where in photography you think we often make confusions, or not using the right semantic that would be very interesting.

Our perceptions, culture and knowledge (or lack of it) are bringing us to communicate ideas and concepts, but are we using the correct words?

It could be very useful that members bring their light to this matter.
Thank you,

Fred.

[Rob C]

Fred, don't you think that people crossing over from film already understand exactly what is being said/meant; isn't it, in fact, helpful to have a certain amount of verbal carry-over from the fim days if only to aid understanding by understood comparison if not by semantic accuracy?

Of course film grain isn't the artifact effect; neither is paper granularity the same thing as the 'look' of the ink put down by a digital printer, which isn't the same thing as the surface appearance of one kind of paper compared with another... it becomes endless. But is there really a problem?

To be honest, I think that you can destroy photography through too much picking of nits, you can reduce it to a mechanical exercise, a technical feat that ends up forgetting all about the most important factors: message and content.

Rob C

[fredjeang]

Of course Rob, the end of your post is totally true.
But that was not the sense of my questions. Yes, there is a sort of mist that is not bad at all in a way and preserving a certain kind of mystery is healphy.
But I also find that there are a lot of technical debates and expressed feeling that ended use any concept in any form, so it's more about getting a correct information. Writters do that constantly, but it does not have to kill the artistic, emotional, and content. I'm not thinking of any rule, any type of conduct,
I simply think that some aclarations would be truly interesting.

Fred.

[mike.online]

Fred,

As a Computer Scientist first, and a Photographer second, I too think that often these words are used incorrectly. In the end it doesn't matter too much, but it can often irk me, and it makes it harder to trust what the author is saying.

In this instance, we are looking at grain, noise and artifacts as characteristics of of an image, and pixels and dots as the way that light is recorded.

between pixels and dots, I find that we are looking at a digital system of discreet boundaries (where images are made of exact sizes from specific resolutions) with pixels and in the film realm we look at the way a film records light over a surface. Both systems when printed or view at the correct size and resolution should look just about right with no problems.

however, when we enlarge or 'up-res' an image different things happen between digital and film. Because digital images are made is discrete colors in discreet locations (pixels) as tiny squares, when we make an image too large we start to see jagged edges or artifacts as the software tries to make a 'best guess' for what color should go in the extra pixels caused in the "up-res" process.

when we enlarge in the film context (and this is something I know less of) we are trying to stretch the image captured in the negative larger, which causes us to loose sharpness in the image, as the projected light has larger area to show transitions of light and color.


now, speaking of noise and grain again, its a bit different. whereas the artifacts and sharpness deal with making an image larger, the noise and grain have more to do with the amount of available recorded light. To get around shooting in a low light situation we use film that has different ASA/ISO ratings, right?

what the higher rated films are doing is trying to get more from less light. This is often called the signal to noise ratio, which basically says we are trying figure out more about the scene from less information. This works, but there are consequences for it. when there is less information (signal) and we use higher ASA/ISO film be more sensitive to that light, it results in more noise / grain. an analogy is thinking about radios, when the person trying to talk to us is far away or has bad signal we turn up the gain, but that introduces more white noise, which is like the grain/ noise in a photograph.


back to noise and grain. the difference between these two (after that long-winded and ultimately not very useful explanation) is that noise is a digital problem which comes from less photons of light hitting the digital sensor in the camera that can be recorded in the analog-to-digital conversion done by the camera. In the film world there is no analog-digital conversion, so the imperfections that result are different and a bit more random, and called noise.

So really, noise is the digital term and grain is the analog one.


caveat: I'm no expert in noise and grain, so i could be far off in my explanations. This is just how I understand it. Likely, there will be someone on the forum who can clear up the errors I've made above. it is teaching me a few things about what I don't know well enough!!


Lastly, there are a lot of pretty great sites and papers that explain this far better than I do both in technical and non technical terms. Hopefully I haven't confused the issues more!

- Mike