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Photo Retouching "Improving" photos, post-production, correction, etc.

is it better to start retouch with a flat image?

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  #11  
Old 04-08-2015, 06:47 PM
insmac insmac is offline
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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.
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  #12  
Old 04-09-2015, 02:20 AM
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AKMac AKMac is offline
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Re: is it better to start retouch with a flat imag

Quote:
Originally Posted by insmac View Post
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!

Last edited by AKMac; 04-09-2015 at 02:28 AM.
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  #13  
Old 04-09-2015, 04:09 AM
captain_j_hook captain_j_hook is offline
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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.

Last edited by captain_j_hook; 04-09-2015 at 04:24 AM.
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  #14  
Old 04-09-2015, 03:31 PM
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andrewrodney andrewrodney is offline
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Re: is it better to start retouch with a flat imag

Quote:
Originally Posted by captain_j_hook View Post
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:
Quote:
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.
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  #15  
Old 04-09-2015, 05:04 PM
captain_j_hook captain_j_hook is offline
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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?
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  #16  
Old 04-09-2015, 06:23 PM
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andrewrodney andrewrodney is offline
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Re: is it better to start retouch with a flat imag

Quote:
Yes, exactly. LR and ACR curves and moves impact luminance and saturation and I think this is a bad idea.
Good thing you didn't write Photoshop, ACR and most of Lightroom ;-)
Did you see what Thomas wrote about doing it your way rather than his way?
Quote:
And I don't get what do you mean with white and monochromatic light.
Are you familiar with what Lab is and how it was created? It's based on it's father, CIE XYZ (1931). The CIE came up with the term standard observer to describe a hypothetical average human viewer and his or her response to color. This was conducted in rigid controlled conditions where volunteers were shown two projected single solid colors next to each other using white and monochromatic light. The results of these tests produced a mathematical model of a color space formulated not on any real-world device, but rather on how we humans (the standard observer) actually perceive or should perceive color. CIE XYZ uses three spectrally defined imaginary primaries: X, Y, and Z. In 1976, CIELAB and CIELUV were added to the mix of these device-independent color spaces. The CIELAB color space is a synthetic, theoretical color space derived from XYZ. Unlike the original, CIELAB has the advantage of being perceptually uniform (sort of . . .). That simply means that a move of equal value in any direction at any point within the color space produces a similar perceived change to the standard observer. As you can see, this was all done long before Photoshop or digital imaging came about. Lab colorimetry is a reliable tool for predicting whether two given solid colors will match when viewed in very precisely defined conditions. It is not, and was never intended to be, a tool for predicting how those two colors will actually appear to the observer or for image editing.
Quote:
And what's the dreaded blue magenta color issues you experienced in LAB?
Keep in mind that CIELab was just an attempt to create a perceptually uniform color space where equal steps correlated to equal color closeness based on the perception of a viewer. The CIE didn't claim it was prefect (cause its not). Most color scientists will point out that Lab exaggerates the distance in yellows and consequently underestimate the distances in blues. Lab assumes that hue and chroma can be treated separately. As for the blue shifting you ask about, there is an issue where hue lines bend with increase in saturation perceived by viewers as an increase in both saturation and a change in hue when that's really not supposed to be happening. Further, according to Karl Lang, there is a bug in the definition of the Lab color space. If you are dealing with a very saturated blue that's outside the gamut of say a printer, when one uses a perceptual rendering intent, the CMM preserves the hue angle and reduces the saturation in an attempt to make a less saturated blue within this gamut. The result is mathematically the same hue as the original, but the results end up appearing purple to the viewer. This is unfortunately accentuated with blues, causing a shift towards magenta.

But enough color history. You say the ACR engine can't separate H from L from S yet as I asked, how do you think HSL in both products operates?
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  #17  
Old 04-09-2015, 07:43 PM
rudym rudym is offline
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Re: is it better to start retouch with a flat imag

704_flat.jpg

704.jpg
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  #18  
Old 04-09-2015, 07:50 PM
rudym rudym is offline
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Re: is it better to start retouch with a flat imag

Its up to you what you want to do with your image or were you want to start and end. You are the creator.

https://www.flickr.com/photos/rudymcfarlane/
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  #19  
Old 04-10-2015, 01:05 AM
klev klev is offline
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Re: is it better to start retouch with a flat imag

Quote:
Originally Posted by andrewrodney View Post
If you are dealing with a very saturated blue that's outside the gamut of say a printer, when one uses a perceptual rendering intent, the CMM preserves the hue angle and reduces the saturation in an attempt to make a less saturated blue within this gamut. The result is mathematically the same hue as the original, but the results end up appearing purple to the viewer. This is unfortunately accentuated with blues, causing a shift towards magenta.

But enough color history. You say the ACR engine can't separate H from L from S yet as I asked, how do you think HSL in both products operates?
CMMs do a lot of weird things, but perceptual mode is still broken. I have yet to see a single decent implementation of it. LAB has other issues. What I think he doesn't understand is that you can't necessarily even separate the two in any practical manner. You can balance a color space around cone response, as was done with the LMS space. It's not usable for most things though.

Quote:
Originally Posted by captain_j_hook View Post
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?
Everything you learned is incorrect. I'm not sure where you read it, but you picked bad sources of information. For the LAB problem, you can see it by scaling the A and B channels. As for it being a bad idea, we don't have any good way to model a lighter version of the same color without variation. Part of the reason is that color models do a poor job of modeling various phenomena such as absorption, most of these models use non-linear computation, and non of them guarantee spectral alignment. They use the rule where if two colors appear the same under the same conditions by their measurement standard, they are equivalent. If you're interested in this I can suggest some reading material.
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  #20  
Old 04-10-2015, 03:29 AM
rudym rudym is offline
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Re: is it better to start retouch with a flat imag

- Start with a well expose image
- Select most important white point
- Select your black point
- Adjust your midtone
- Set your 1/4 and 3/4 tones
- Increase or reduce contrast
- Find your channel midtone
- Set your saturation level

(Video term: Color Grade if you want)
If you don't like what you see start over.

Look up Tone System on the web.
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