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07-04-2009, 08:54 AM   #1
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Super Saturation

I have found my red rose pictures taken under a light cloud cover are over saturated in red. Other colours seem OK.
I view them with CS3. Reducing saturation and vividness seem to help but the results leave something to be desired.
Could I have set something incorrectly?

07-04-2009, 09:21 AM   #2
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Browse around this fourm (or maybe its the DSLR forum) for another current thread on this same topic. It's a common issue, and not easy to solve, but underexposing a little and fiddling with the images in RAW processing can help.

EDIT - Here's that thread:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/65068-red-saturation-issues.html

Last edited by Marc Sabatella; 07-04-2009 at 09:35 AM.
07-04-2009, 11:47 AM   #3
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1) Shoot RAW if you can. You'll be able to control the saturation better.

2) When shooting, view the RGB histrogram to see if you notice any clipping in the red channel.

You might also consider (for RAW/ACR processing only) rendering the image into a wide-gamut color space such as ProPhotoRGB so as to better "contain" the saturated reds....although that could also introduce the issue of your display profile clipping the saturated reds anyway. In this scenario, the saturated reds may not be clipping (they have detail) in ProPhoto but the display itself isn't able to display the reds in ProPhoto w/o clipping them but they may print just fine. Unless you have a rather high-end display like an EIZO CG series or similar, chances are that your printer (Epson with either Claria or Ultrachrome inks for example) has a wider gamut than your display. Colors that may clip to the display may print with nice detail to a good printer using a good media such as Ilford Gold Fiber Silk or similar. These better printer/media combinations can actually exceed AdobeRGB in certain color areas.

These days, with RAW rendering to wide-gamut spaces and with current printer/ink/media capabilities, the display is quickly becoming the limiting factor ("smallest" color container in the imaging pipeline) unless you go for the latest high-end wider gamut displays.

Regards,
Terry
07-09-2009, 01:51 AM   #4
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"I have found my red rose pictures taken under a light cloud cover are over saturated in red. Other colours seem OK."
You don't identify the camera but I had the same problem with the K10 until I used the highest colour space abailable in Bridge then down sampled the image to sRGB or Adobe RGB 1998 as needed. The latger colour space will pritect your reds and so on and Adobe Bridge can save in a lower colour space without losing the saturation in the reds.
Ron McDermott

07-09-2009, 02:07 AM   #5
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This is something that applies to all Pentax DSLRs (not sure about film), something we live with/work around or take advantage of.
07-10-2009, 06:33 AM   #6
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Converting from wide gamut to smaller gamut profile will STILL clip

QuoteOriginally posted by photog Quote
"I have found my red rose pictures taken under a light cloud cover are over saturated in red. Other colours seem OK."
You don't identify the camera but I had the same problem with the K10 until I used the highest colour space abailable in Bridge then down sampled the image to sRGB or Adobe RGB 1998 as needed. The latger colour space will pritect your reds and so on and Adobe Bridge can save in a lower colour space without losing the saturation in the reds.
Ron McDermott
I assume you mean *converted* to either sRGB or AdobeRGB. *Down-sampling* is what you do to change the resolution.

The fact is, all things being equal, if you first render the raw file into a wide gamut space such as ProPhotoRGB to prevent clipping and then convert to one of the smaller standard working spaces, clipping will still occur. The reason is that all of the standard Adobe-supplied RGB working space profiles, and a few of their CMYK ones as well, will only perform a *relative colorimetric* conversion EVEN IF YOU CHOSE PERCEPTUAL RENDERING in the conversion dialogue. Bottom line, rendering into ProPhoto and then converting to sRGB is really no different than rendering into sRGB in the first place...the amount of color clipping will be the same.

There's really only a couple of options for preventing clipping:

1) Once you've rendered into a wide gamut space such as ProPhotoRGB, you use Photoshop to then reduce saturation to bring the saturated colors within the gamut of the smaller gamut space that you intend to convert to to. You can use the gamut warning and soft-proofing in Photoshop as a guide to tell you when you have the colors sufficiently corrected so they do not clip when converting to the smaller gamut destination profile.

2) Once rendered into ProPhotoRGB, you convert to a destination profile that is a *LUT-based* profile, not a matrix-based profile (all of the standard RGB "working space" profiles supplied by Adobe are matrix-based profiles and do not have a perceptual rendering table). A LUT-based profile will generally have both colorimetric and perceptual rendering tables so that when you choose the perceptual intent, you'll get a true perceptual rendering that will normally prevent clipping (but not always). GENERALLY SPEAKING most printer/output profiles, both RGB and CMYK, are LUT-based profiles.

The only way to know POSITIVELY whether a particular profile is a matrix or LUT-based profile is to use a utility such as ColorThink by Chromix or perhaps the ColorSync utility.

Regards,
Terry Wyse
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