is it better to start retouch with a flat image?

[Renato Gonçalve]

Hello everyone. I've been watching the forums for a while and never really had anything to say. Up until now.

I've been wondering if it is better to start of with a flat image or with a fairly close luminosity and contrast desired for the final image. See, as i understand, uncontrasting the image beyond the point of necessity would make it harder to bring back all the details compressed in the image, having to put way more work on luminosity and color correction that it would if you just started of with something close the final image.

Am i missing something about it? Like something about how photoshop works when extracting the data from the uncontrasted raw conversion?

[skoobey]

Re: is it better to start retouch with a flat imag

You start with an image that resembles the final results, going "flatter" means not introducing additional unnecessary contrast in the RAW converter. But, you want to make sure there is detail in some blacks, so you lift those a bit (not to make it flat, but to make sure there are no "empty" spots), you may or may not clip them later on in the retouching.

Obviously, sometimes you need separate conversions for blown out and clipped things, like the sky, black clothes etc. You don't do those to make an image "flat", but to bring detail where it's lacking in a single conversion.

Hope I helped.

[Renato Gonçalve]

Re: is it better to start retouch with a flat imag

Surely you did.
I'm asking that though because i have seen photographers starting to work, and i have been asked to start, on a fairly uncontrasted conversiona and tought that imay have missed something.

[skoobey]

Re: is it better to start retouch with a flat imag

Well, removing contrast by pulling the contrast slider is something I never do, but sure, adding some detail in the shadows or highlights using those adjustments is fine(blacks, darks, lights and whites for ACR/LR users).

More detail=less contrast in the image.

Just like more dynamic range=flat, but that is because all those finer transitions are present, rather than being clipped.

[AKMac]

Re: is it better to start retouch with a flat imag

It depends on the sort of image and the look you're aiming for. The default for ACR/LR is more or less flat, and it can look a bit washed out to start with. You have to work harder, but you've got more control. On the other hand, the default for Capture One tends to be more saturated and contrasty, and looks more seductive. Some people prefer a starting point that looks good and helps them to visualise the final look earlier on. Other people are more cautious and like to work the image up gradually.

[andrewrodney]

Re: is it better to start retouch with a flat imag

I've been wondering if it is better to start of with a flat image or with a fairly close luminosity and contrast desired for the final image. See, as i understand, uncontrasting the image beyond the point of necessity would make it harder to bring back all the details compressed in the image, having to put way more work on luminosity and color correction that it would if you just started of with something close the final image.

Depends on the data; raw or rendered (baked). If the former, there's zero reason as all you are doing is creating instructions to render the image and unless the raw converter you use is rather poor, or you're rather poor using it, all you're doing is defining instructions to produce an image you'll take into (probably) Photoshop and 'retouch'. It's pointless to feed PS poor data and then attempt to 'fix' it.

[klev]

Re: is it better to start retouch with a flat imag

Luminosity is a loaded term. It just tells me that too many people don't understand the way RGB works. You want something that allows you to make sufficient changes as necessary. Sub-strategies exist to further that goal.

[andrewrodney]

Re: is it better to start retouch with a flat imag

Luminosity is a loaded term.

In fact, it's the wrong term as applied in Photoshop!
Brightness is a perceptual phenomena. Luminance (Luminosity) is a measure of the total radiant energy from a body. It has nothing to do with what a human perceives but rather describes the total radiant energy, such as watts/second of a source (the surface of a radiating object like a display). In Photoshop, the layer mode called luminosity is not what's occurring (I was told its something like the "Luma" which is an old TV RGB transform). If the luminance of a viewed light source is increased 10 times, viewers do not judge that the brightness has increased 10 times.

Lightness is a perceptually scaled component of color, the axis seen in Lab (Lstar) from light to dark. It IS the L in HSL.

[Renato Gonçalve]

Re: is it better to start retouch with a flat imag

Luminosity is a loaded term. It just tells me that too many people don't understand the way RGB works. You want something that allows you to make sufficient changes as necessary. Sub-strategies exist to further that goal.

Since you understood my doubt i will say that this is more about semantics than technical hehe. And altough that's a far to broad answer to what i'm asking it is clear enough to answer it.

thank you.
And also thank you Andrew.

[klev]

Re: is it better to start retouch with a flat imag

In fact, it's the wrong term as applied in Photoshop!
Brightness is a perceptual phenomena. Luminance (Luminosity) is a measure of the total radiant energy from a body. It has nothing to do with what a human perceives but rather describes the total radiant energy, such as watts/second of a source (the surface of a radiating object like a display). In Photoshop, the layer mode called luminosity is not what's occurring (I was told its something like the "Luma" which is an old TV RGB transform). If the luminance of a viewed light source is increased 10 times, viewers do not judge that the brightness has increased 10 times.

Lightness is a perceptually scaled component of color, the axis seen in Lab (Lstar) from light to dark. It IS the L in HSL.

I didn't intend to spawn a technical discussion on it, especially as these things are defined in weird manners that are often split between derivation as a matter of watts per steradian and average cone response depending on color space. When people refer to luminosity in the context of photoshop, they imagine some some hue invariant mapping. In my experience it never works well.

Since you understood my doubt i will say that this is more about semantics than technical hehe. And altough that's a far to broad answer to what i'm asking it is clear enough to answer it.

thank you.
And also thank you Andrew.

Well it's difficult to come up with a perfect strategy. There are some things that are easier to do during raw processing, because you're working with a larger set of data. Upon processing the data, you typically export to a different color space. Anything that falls out of range is basically clipped/clamped. Perceptual conversions claim not to do that, but they are a lie (not sure why they were never removed).

[insmac]

Re: is it better to start retouch with a flat imag

From my point of view, it depends whether you feel certain regarding your corrections in raw processor.

I see nothing wrong in a shaping an initial contrast curve and any other adjustments taking the image further than a neutral, true-to-life output. It's just it will be harder to get back to a clean state afterwards, but other than that, don't worry about every pixel and push the sliders the way you want. There is no single way to deal with it and being afraid of loosing a fraction of control because you don't apply a certain effect on an adjustment layer will drive you nuts. Don't worry about it.

Also, from my experience with Lightroom from day one (from the first beta) it's not that it's output is flat - its colour rendering and local contrast are inferior to the ones coming from Capture One.

[AKMac]

Re: is it better to start retouch with a flat imag

From my point of view, it depends whether you feel certain regarding your corrections in raw processor.

Yes, it's all about vision, confidence and judgement. If you're producing your own work you may make quite radical moves at the raw processing stage, working fast and decisively to keep your vision fresh, and bringing the image into PS with virtually no detail in the shadows and the colour pushed to clipping. After all, it's not the end of the world if you mess up and have to start again. And you may know from experience that if you take a timid, risk averse approach, you're going to end up with timid, risk averse results. There's no point in being precious about something that's of little value.
HOWEVER, you also discover that what seems like a good idea on Tuesday may often appear like piece of shit on Wednesday morning, so you learn from that (hopefully), and get better at making judgements.

So you may decide to adopt a different strategy, But ultimately it's still true that vision comes first and you'll get nowhere worthwhile if your first priority is safety.

BUT - If you're working for a client, or worse still, a client who is working for ANOTHER client, then you may need to adopt a different approach for obvious reasons, and adopting an organised fully non-destructive workflow may be wise.
It's very important to try to establish as early as possible what the final result is to be. And if the client is vague about that, then send him/her some quick initial ideas from understated to extreme. You may find that what you thought was too much is still not enough. It's better to take this approach right at the start rather than pussyfooting around, moving an inch at a time when you're a mile out!

[captain_j_hook]

Re: is it better to start retouch with a flat imag

Since raw converters such as CR and LR don't separate color from lightness I think making a decent curve functioning as a starting point is never a good idea. There is no color consistency 100%! There will always be something going beyond your control and I find it's not acceptable. You can make a curve in CR and LR or start from a jpg made on the fly by the photographer or the client but just as a general referring idea... then you should export a flattened version and work on that one. it's you knowing where and when to clip and separating color from contrast and doing things properly, still achieving the same result obtained "randomly" eith a curve in CR or LR.

[andrewrodney]

Re: is it better to start retouch with a flat imag

Since raw converters such as CR and LR don't separate color from lightness I think making a decent curve functioning as a starting point is never a good idea.

So HSL corrections in LR/ACR are doing what specifically?

According to Thomas Knoll:

While developing Camera Raw, I experimented with a pure luminance curve (as Simon suggests). However, based on my testing results, I rejected this algoirthm since it produced results that were most often visually worse looking that the tone curve algorithm actually used by Camera Raw (which is a special hue-preserving curve, NOT three indepent curves as Simon incorrectly assumed). The saturation effects that Simon considers a defect is actually something that most users actually want.

Curves in LR/ACR are hue protected, meaning it only impacts luminance and saturation (2/3 of the HSL potential). A normal tone curve in Photoshop does twist the hue, saturation and luminance. That's the differences. And again, Thomas did this on purpose.

Lab assumes that hue and chroma can be treated separately, but numerous experimental results indicate that our perception of hue varies with the purity of color which is exactly what Thomas is reporting. Mixing white light with a monochromatic light does not produce a constant hue, but Lab assumes it does! This is seen in Lab modelling of blues. It's the cause of the dreaded blue-magenta color issues or shifts.

[captain_j_hook]

Re: is it better to start retouch with a flat imag

Yes, exactly. LR and ACR curves and moves impact luminance and saturation and I think this is a bad idea. I always treat light and hue separately. And I don't get what do you mean with white and monochromatic light. Treating light separately in LAB doesn't produce ANY hue, so there is no constant hue at all. Hue is something you'll think about once you go to color a-b curve.
And what's the dreaded blue magenta color issues you experienced in LAB?