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Overpowering Redness
Lens: Pentax D FA Macro SMC 100mm F2.8 WR Camera: Pentax KP Photo Location: Friend's Garden Ipswich Queensland ISO: 1600 Shutter Speed: 1/125s Aperture: F13.5 
Posted By: K2 to K50, 11-05-2019, 06:29 PM

The bane of saturated reds rears it (??) head again, but I couldn't resist trying.


Name:  PETE2675.jpg
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Last edited by K2 to K50; 11-05-2019 at 08:05 PM.
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11-05-2019, 06:32 PM   #2
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Looks pretty good. I take it that it should be ISO 1600, not 16000, right?
11-05-2019, 08:07 PM   #3
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QuoteOriginally posted by The Squirrel Mafia Quote
Looks pretty good. I take it that it should be ISO 1600, not 16000, right?
Oh, boy - RED face, now!!! Hee hee - you got me: I have now corrected it. Thanks, Squirrel. By the way, I love your avatar!!
11-05-2019, 08:14 PM   #4
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If you use a PP program such as Photoshop you can correct this problem by increasing the contrast slightly then reducing the brightness until the red looks natural.

11-05-2019, 08:25 PM   #5
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QuoteOriginally posted by eaglem Quote
If you use a PP program such as Photoshop you can correct this problem by increasing the contrast slightly then reducing the brightness until the red looks natural.
I have currently fiddled with Irfanview 64bit, Paint.net, Pentax/Ricoh's Digital Camera Utility, and, inevitably, Microsoft's Photos app, all at a very shallow level. I have successfully (barely!!!) lightened some underexposed shots. But am very much a novice at understanding the effects of the available tools, and even more of a novice at using them. But I will see if I can do what you have suggested, here, eaglem. Thank you.
11-05-2019, 09:09 PM   #6
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QuoteOriginally posted by K2 to K50 Quote
I have currently fiddled with Irfanview 64bit, Paint.net, Pentax/Ricoh's Digital Camera Utility, and, inevitably, Microsoft's Photos app, all at a very shallow level. I have successfully (barely!!!) lightened some underexposed shots. But am very much a novice at understanding the effects of the available tools, and even more of a novice at using them. But I will see if I can do what you have suggested, here, eaglem. Thank you.
No problems, we're here to help Would you mind if I download that shot and see if something can be done?
11-06-2019, 12:02 AM   #7
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QuoteOriginally posted by eaglem Quote
No problems, we're here to help Would you mind if I download that shot and see if something can be done?
Not at all - would be very interested to see what you come up with, eaglem. I presume you mean to download the raw file on the OneDrive link? But whichever, go fo it!

11-06-2019, 01:41 AM   #8
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I just copied and saved as so not sure how good the quality of the file was but this is the best I could do with it.



---------- Post added 11-06-19 at 04:45 PM ----------

or this

11-06-2019, 02:47 AM   #9
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QuoteOriginally posted by eaglem Quote
I just copied and saved as so not sure how good the quality of the file was but this is the best I could do with it.



---------- Post added 11-06-19 at 04:45 PM ----------

or this
Well, eaglem, I think that has made the red even more saturated, even perhaps a little smudged, and lost a lot of detail, especially in the centre. If you copied and pasted from this thread, that is a relatively small jpg file. I am not sure, but if you clicked on the pic here in the thread to go to the Onedrive link, I think you may have been able to "Download" (from the menu in OneDrive) the original .DNG file, which may give you a lot more to work with. Otherwise, thanks for the effort and time: I will use your suggestion myself in either Irfanview or Paint.net to see if I can achieve anything.
11-06-2019, 02:57 AM   #10
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QuoteOriginally posted by K2 to K50 Quote
Well, eaglem, I think that has made the red even more saturated, even perhaps a little smudged, and lost a lot of detail, especially in the centre. If you copied and pasted from this thread, that is a relatively small jpg file. I am not sure, but if you clicked on the pic here in the thread to go to the Onedrive link, I think you may have been able to "Download" (from the menu in OneDrive) the original .DNG file, which may give you a lot more to work with. Otherwise, thanks for the effort and time: I will use your suggestion myself in either Irfanview or Paint.net to see if I can achieve anything.
I think the size of the image had a lot to do with it plus the fact you'd already done some PP when you uploaded the shot which wouldn't have helped.
11-06-2019, 05:09 AM   #11
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QuoteOriginally posted by K2 to K50 Quote
Not at all - would be very interested to see what you come up with, eaglem. I presume you mean to download the raw file on the OneDrive link? But whichever, go fo it!
I found that interesting too and hope that's an open invitation, even though it was directed at our resident rose expert. I downloaded the DNG and checked: It's well-exposed in the sense that no channel is clipping and noise in the darker parts still lets textures on the petals come though - just. Saturated reds are somewhat tricky to render in sRGB. The red primary color is fairly "pale", so the red channel easily clips. For an illustration: all the visible reds outside of the sRGB triangle (color not to scale) in the chromaticity diagram have to be mapped into the triangle. The situation is not much better with AdobeRGB, btw. E.g., the color spaces of newer video standards cover a much wider gamut in the reds. Of course, we can't work with more than the sensor is able to differentiate either, so it is not as severe of a limitation as it looks.


Back to the RAW data. I tired a somewhat natural rendition to demonstrate what a largely non-clipping version would/could look like. Starting from a 'neutral' (fairly flat) rendition, I tamed down the highlights by flattening the tone curve in the higher values (Highlight compression = 67 in Rawtherapee). The camera's color balance measurement was off due to the amount of red. Being mostly backlit by sunlight, I manually set it to 'shade' (=6200K). I adjusted contrast to +10 (default in RT is very flat) and first lowered exposure, until only a tiny fraction of the petal highlights remained clipped. That turned out very dark, so I added a virtual graduated density filter of 1EV strength, gradient going from bright in the lower left to dark in the top right, dimming the highlights but still looking natural, which allowed to pull exposure back up to +/-0. A -0.6EV vignette helps to make the subject stand out a little more (dampen the right-top highlight more without affecting the center). Finally, I used RT's Tone Mapping (tamed down to 0.25 from way too big default of 0.5), resulting in increased local contrast and thus accentuated texture and stamens and lifting (too) deep shadows. The result looks OK to me for rendering on a monitor, preferably with a dark background (try the style selector at the bottom of the forum page). It would not print well at all though.

For a brighter background, like the default here in the forum, or for a print, which provides much lower contrast (~1:100) than the backlit screen (~1:1000), one has to trade off color fidelity for brightness. In order to partially compensate visually, as eaglem suggested, contrast can be increased. In the brighter example, I tweaked the tone curve for higher brightness and stronger contrast on the petal mid-tones, used RT's 'Local Contrast' settings (focusing on brighter parts) for even more accents and 'Dynamic Range Compression' (a global tone mapping operation) to fit everything into a smaller tone range. Even though saturation is clearly lacking in places now and colors are slightly off (easy to totally screw up if any of the above is pushed too far), this highly processed version still looks like a convincing rendition of a backlit red rose in bright daylight to me.

A white or silver reflector to brighten up the flower using natural light would likely have made the post-processing much easier.
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Last edited by JensE; 11-06-2019 at 05:17 AM.
11-06-2019, 05:47 AM   #12
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Well done Jense, I didn't use the RAW Data but just downloaded the Jpeg which is why not much could be done.
11-06-2019, 08:18 AM   #13
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QuoteOriginally posted by K2 to K50 Quote
Oh, boy - RED face, now!!! Hee hee - you got me: I have now corrected it. Thanks, Squirrel. By the way, I love your avatar!!
It's a little Japanese "kao" (face) gif. I love that it's queuing a record & listening to the beat as it's about to tear down the dance floor at the club. Hahaha! I found it many years ago & use it in a lot of other forums & stuff.
11-06-2019, 05:36 PM   #14
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QuoteOriginally posted by JensE Quote
I found that interesting too and hope that's an open invitation, even though it was directed at our resident rose expert. I downloaded the DNG and checked: ............

A white or silver reflector to brighten up the flower using natural light would likely have made the post-processing much easier.
JensE, I like both of the renditions you have done here. The first does a nice job of emphasising the backlit effect of the sun being behind the flower, and increases definition to the edges of the petals. The whole is darker, but the detail of the centres has not been lost.
The second does not emphasise the back-lit effect (in fact almost loses it) but adds (cf my original) definition to the edges of the petals, and again, retains the definition of the flower centres.


Either one is an improvement on my original. I would love to have sat beside you and watched you perform this software magic - the amount of text I have left out of my quote of your post (for the sake of brevity) is probably a good indication of how much I was able to follow your technical explanation of what you did. Brings to mind a song from a 1960's group who called themselves "The Incredible String Band" in which some of the lyrics went a bit like this:

":You know all the words
,,,,,,,,,,,,,,,,,,
But you never understood the song, she said"

Obviously you had a lot more to work with than eaglem, by downloading the DNG file.

I thank both of you for putting in the effort and time - it has been a real education of what CAN be done, even if the HOW of it, at this stage, went over my head. And you have me wondering about carrying along some kind of roll-up reflector material in my camera backpack in future photographic field trips.

---------- Post added 11-06-19 at 05:42 PM ----------

QuoteOriginally posted by The Squirrel Mafia Quote
It's a little Japanese "kao" (face) gif. I love that it's queuing a record & listening to the beat as it's about to tear down the dance floor at the club. Hahaha! I found it many years ago & use it in a lot of other forums & stuff.
Well, the little guy is certainly "groovin and bouncing". Love it. Combined with that absurd pseudonym of yours (which I also love!) it makes for an not easily forgotten impression!

Last edited by K2 to K50; 11-06-2019 at 05:44 PM.
11-06-2019, 05:59 PM   #15
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Collapsible ones in 12" are easy enough to pack and most times sufficient for details: Collapsible Reflectors | B&H Photo Video
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