Scene/display-referred, rgb, Lab....help

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Scene/display-referred, rgb, Lab....help

Shaikailash

Hi all, I noticed that many tutorials assume the viewer is familiar with what scene-referred & similar terms mean, what a color space is, what sRGB means, what a tone curve is, etc...

As a complete newbie I struggle with this. Ok, I understood that people suggest to adopt a scene-referred RGB workflow, also "linear", but what does this imply in practice? Could you recommend some articles or tutorial for dummies which guide the newbies to understand what is important to understand? Thanks

P.S. I found some articles which were supposed to clarify this, yet it doesn't help to read stuff like this: "First of all, what do we mean by “linear”? If y is linear with respect to x, it means there’s a relationship between x and y in the form y= a . x + b, where a and b are real constants. Linear means proportional to something plus or minus a constant."

MrSteveVee

I am sure that someone more clever than me can answer, but from my viewpoint I find that some poeple like to go deep into the technology of how image manipulation works and others like to manipulate an image with no desire to know how it works under thehood so to speak, I am the latter unfortunaly so from my viewpoint half of this stuff is unecessary to know. This means I know enough about the basic foundations to manipulate an image witthout needing to know how it works or the technical terms used for it
So to answer you 4 questions,
Scene defered, no idea, never had any call to even look it up
Color space: This is important and until you understand it, use sRGB that will be the default for now. Why? For a human, the colour space is te range of colours we can use. AdobeRGB Color space is a sub range of this that they have develped that will show an image to its best capabilities. sRGB is the a smaller colour space than AdobeRGB that was developed as a default by MS I believe and is pretty much used by the majority of screens etc. So unless you have a monitor that can siplay AdobeRGB you will only be able to use sRGB as it will not be able to display all of the AdobeRGB colours. This of course is a simple viewpoint and not 100% correct but you see the problem so just use sRGB for nowuntil you pick up a better understanding of what you want to do.
Tone curve. Look at the tone curve in darktable. Reset it to neutral and see how it is just a linier line, and the image is flat looking, adjust the by pulling parts up or down and see what happens, this is the "curve" and a pre-determined tone curve based on camera/model is applied to each raw image automatically when developing ao that the developed image resembles the look of the camera Jpeg image as your starting point
Steve.

jaw-dt

MrSteveVee Scene-Referred workflow and filmic rgb are sometimes used interchangeably but filmic is really a tool in the Scene-Referred workflow.

jaw-dt

Color space is a group of colors that the specific color space has. Adobe RGB and sRGB are color spaces. See color space here This tutorial here shows how to edit a photo in Scene-Referred workflow here with links to additional information.

Shaikailash

I'll try that tutorial, thanks and I now understand why I was confused since filmic is (mis)used to indicate the scene-referred workflow, but it's also the name of a tool!

I'm like you MrSteve, I don't really want to learn the technicalities but really only learn to edit my pictures. It's just that since I'm starting from scratch I thought to maybe learn the "new" workflow which is recommended, which is scene-referred as far as i understand, and i was a bit lost. a bit less lost now will surely come back with more questions

kevdoneil

I find myself in the same situation as Shaikailash in that I am very new to the world of digital photography and even newer to photo-editing applications. I have been reading up on scene-referred/display-referred trying to determine which to use. Initially thought "display" was the way to go since it seems to me that that is the final product, it is what the viewer sees, but many of the contributors to the Y/T dt group, when describing their process seem to use "scene". When I use dt in the "display-referred" images are displayed initially quite dark, but when I check the options box to "scene-referred" images tend to display a little over exposed. Do the different modes of editing have to do with where the adjustments place themselves in the path to the final product (what we see)? I do not know. Still trying to understand the pros and cons of each method. If anyone has more precise info on this your input would be greatly appreciated.

jaw-dt

The usual cause for dark images in diplay-refered is the base curve not being applied. Sometimes there is no specific basecurve for your specific camera model, and a generic or a custom curve you create will need to be used.
With scene-refered the exposure is automatically bumped by .5, this may not be correct for your camera, there is also a check box whether to use the exposure compensation setting from the camera. These may account for some of the difference you see. Also you may need to reset the history stack for the image if you change between these modes to get a better idea of the differences.

My suggestion would be to just chose one, the pros and con can drive you nuts and switching back and forth when new to post processing will do the same. I use scene-refered. YMMV.

kevdoneil

First of all, YMMV? "Your Method May Vary" I guess? I shoot with A Canon 5D Mark 4. I open pre-sets under basecurve and it selects "canon eos like alternative". Not sure why "alternative". It should just be "canon eos like". Right? Oh well, minor issue. Am I right about this question I asked in my previous message? "Do the different modes of editing have to do with where the adjustments place themselves in the path to the final product (what we see)? " This is a steep learning curve.

jaw-dt

YMMV translation 'your mileage may very" or used loosely your results may not be the same. You can create a preset to auto apply the "canon eos like". Per the dt web site there is no custom profile for the mk4, though the 1,2 and 3 all have there own.
Were the different edits are place is controlled by what is referred to as the pipeline this is predetermined, this edit follows that and so forth and is different for scene and display referred. This is not the same as the history stack you see in the darktable mode which is the order which you preformed the edits.

kevdoneil

Maybe I am thick, but first you refer to "the pipeline" as being predetermined, "this edit follows that". And then you state the history stack is "the order in which you performed the edits", but these two are not the same. Are you differentiating between the edits automatically applied and the edits I make?

jaw-dt

The pipeline controls the order of the edit whether they are automatically applied or the one you make.

kevdoneil

Thank you.