Bringing Out a Flower with Lab Processing

[xpatUSA]

Many of us like to shoot flowers, including myself. Generally, we'll use DOF to bring out the flower against the background and, if possible, use available lighting to further emphasize the bright flower against a darker background. Such was the basis of this shot:



A pretty shot and, with it's visitor, a bit of a keeper. But that light purple is not strongly at the fore, IMHO. Our eyes are more sensitive to green and the leaves in the background to the right of the flower draw my eye, even though they are "darker" than the flower.

Of course, there are many ways to skin this particular cat - but RawTherapee has some pretty comprehensive Lab processing options - so I had a go:



Kapow!!

Please open them in the Lytebox and click back and forth to get a good idea of the change.

Why Lab? The main thing about Lab is that you can adjust the brightness without affecting the color saturation. OTOH, you can adjust the color without messing up the image tones too much. Similar adjustments in the RGB mode are far more interactive, in my experience.

Why RawTherapee? The Lab adjustments include curves in addition to simple sliders; one curve (CH) gives the ability to adjust the saturation** of individual hues without affecting other hues.

** (well, chroma actually, which is not the same as the S in HSB)

So, here's what I did, briefly:

I applied an 'S' shape curve in Lightness to darken the background and lighten up the flower a bit. In so doing, the flower mid-tones gained a bit of contrast.

I increased the overall chroma a bit by +23 to strengthen the flower color.

I used the Chroma vs. Hue balancer and drastically reduced the chroma of the greens (similar to de-saturating only the greens in an image).

In addition to the Lab adjustments above, I did de-convolution sharpen it just a teeny weeny bit . . .

Comments (except for composition) welcome, good or bad

[Shadowman]

Processing clearly visible, was the stem deliberately darkened to present a floating effect? Nicely processed.

[xpatUSA]

Processing clearly visible, was the stem deliberately darkened to present a floating effect? Nicely processed.

Thank you, John.

No, I didn't really think about the stem during processing but it was shaded from the overhead sun. Therefore, I imagine that it got darkened when I applied the 'S' curve in Lightness.

[Manfred M]

I've played around with the LAB colour space a tiny bit and found it can produce some rather funky looks.

Very few people seem to know anything about it, so I picked up Dan Margulis's Photoshop LAB Color book, second edition and am waiting for the right conditions (probably some rainy day in April) to start working my way through it. I find Margulis is a very knowledgeable author, but I can only digest the material a bit at a time.

[Cantab]

I've played around with the LAB colour space a tiny bit and found it can produce some rather funky looks.

Very few people seem to know anything about it, so I picked up Dan Margulis's Photoshop LAB Color book, second edition and am waiting for the right conditions (probably some rainy day in April) to start working my way through it. I find Margulis is a very knowledgeable author, but I can only digest the material a bit at a time.

Manfred, will you be providing us with a one paragraph summary of the book?

[Manfred M]

Manfred, will you be providing us with a one paragraph summary of the book?

Sure - right now the words long, comprehensive and a tough read come to mind, but I haven't gotten past the introduction yet.

[JBW]

possibly a gnats too much sharpening? Coming from me this will sound almost ironic but have you made the bg too dark? The reason I ask is that in shot one the background is a little strong but in shot two the four yellow areas are more bothersome to me than the bg in shot one.

On the up side you have definitely found a powerful way to work with a bothersome bg.
B.

[xpatUSA]

possibly a gnats too much sharpening? Coming from me this will sound almost ironic but have you made the bg too dark? The reason I ask is that in shot one the background is a little strong but in shot two the four yellow areas are more bothersome to me than the bg in shot one.

On the up side you have definitely found a powerful way to work with a bothersome bg.
B.

Yes, I do like sharp but not to the point of halos.

So, staying in the Lab domain, here's one with a simple approach:

In the CH curve mode, up the flower chroma and down the green chroma, both at the same time!

In the L curve reduce the shadows less than shot 2.

No sharpening applied at all



Another way to skin the cat?

[JBW]

This is all about personal preference ... for me shot 3 is looking better. Now comes the insect?

[IzzieK]

I tried lytebox -- there is not much difference between pp #2 and #3 but very evident in #1 and #2..I like #2. I had dabble in Lab colour a little bit in the past and now forgotten until you mentioned it.

[Manfred M]

I'm not sure I agree 100%. Clipping infers assigning a value of either 0 or 255 to out of gamut (OOG) values. Rendering intents on our operating systems and / or photo editing software use different techniques to prevent this through the icc profiles. With photography, the two most commonly used rendering intents are relative colourmetric or perceptual, and while they work differently, the OOG colours are not clipped per se, but are remapped to values that can be reproduced by the device.

If you have a sRGB display, then both ProPhoto and AdobeRGB images with OOG colours will both need to be reprocessed to ensure these areas are not clipped. If you have an AdobeRGB compliant computer screen, then only the ProPhoto images may need to rendered so that the display can handle all of the colours. Of course, if you post things to the web, all of this is somewhat irrelevant as you are stuck with the "lowest common denominator", i.e. sRGB and unless you are using FireFox (the only browser that is fully colour managed, so far as I know), who knows what you are getting.

Working in the LAB colour space (the widest of the colour spaces) is going to give you the highest likelihood that you have to deal with OOG colours.

[xpatUSA]

I'm not sure I agree 100%. Clipping infers assigning a value of either 0 or 255 to out of gamut (OOG) values. Rendering intents on our operating systems and / or photo editing software use different techniques to prevent this through the icc profiles. With photography, the two most commonly used rendering intents are relative colourmetric or perceptual, and while they work differently, the OOG colours are not clipped per se, but are remapped to values that can be reproduced by the device.

Sorry, poor terminology on my part.

If you have a sRGB display, then both ProPhoto and AdobeRGB images with OOG colours will both need to be reprocessed to ensure these areas are not clipped.

Clipped, or re-mapped to the sRGB gamut boundary?

If you have an AdobeRGB compliant computer screen, then only the ProPhoto images may need to rendered so that the display can handle all of the colours.

Agreed.

Of course, if you post things to the web, all of this is somewhat irrelevant as you are stuck with the "lowest common denominator", i.e. sRGB and unless you are using FireFox (the only browser that is fully colour managed, so far as I know), who knows what you are getting.

As I understand it, most browsers are color-managed these days but I don't know what is meant by "fully".

Working in the LAB colour space (the widest of the colour spaces) is going to give you the highest likelihood that you have to deal with OOG colours.

On that, let's let sleeping dogs lie . . . .

[Manfred M]

Clipped, or re-mapped to the sRGB gamut boundary?

Definitely remapped - at least in the implementations I use.

Perceptual remap all the colours and move the white point to bring the OOG into the colour space, so while everything is in gamut, you have a general colour shift.

Relative colourmetric freezes the white point and applies a non-linear remapping for the in and out of gamut colours that are close to the colour space boundaries so that there is some variability in the colours. I understand some converters do what you say and turn all OOG colours into clipped colours, but I have not worked with any that do that.

[chauncey]

Dan Margulis's Photoshop LAB Color book,

Could be wrong but, I thought that I had read that he was backing off his enthusiasm for a LAB workflow.

[Manfred M]

Could be wrong but, I thought that I had read that he was backing off his enthusiasm for a LAB workflow.

I assume that is why he just put out the 2nd edition of the LAB Color book and suggested in the forward that it can be used for all types of images, not just a special subset (like canyons)?

I suggest you might have heard wrong...

[xpatUSA]

Definitely remapped - at least in the implementations I use.

Thanks - that's what I thought.

I understand some converters do what you say and turn all OOG colours into clipped colours, but I have not worked with any that do that.

I coined the term "saturation-clipping" wrongly and I never meant simple color-clipping. Therefore, I have never worked with any that do that, either. After all, they should all do the same as the tutorial here says, so neither of us is saying anything new!