Simplest way to boost saturation

[M Covington]

What is the simplest way to boost color saturation all over a picture, for all hues?  I'm looking for something analogous to +20 saturation in Photoshop or +20% saturation in DeepSkyStacker.  The specific need is DeepSkyStacker autosave.tif files, which have unusually low color saturation and always require boosting.  Thanks!

[cdesselles]

Use Curves Transformation tool. Select the "S" icon for saturation.  Drag the curve up. That simple.

[georg.viehoever]

Or the ColorSaturation tool, if necessary with Range increased.
Georg

[bitli]

Somewhat contrieved, but you could also extract the L and apply the original image to the L via LRGB channel combination, strongly increasing the saturation (and possibly cleaning some color noise in the same pass).
-- bitli

[M Covington]

Thanks.  Georg: Increasing the Range to about 6 was the key to it.

[jkmorse]

Bitli,

Can you expand on your tip.  I always thought that doing the LRGB channel combination reduced saturation, at least when first combining an RGB with a Lum.  If that is correct (and it might not be), what changes with the second iteration?

Thanks,

Jim

[msmythers]

Jim,

What Bitli is doing is using the LRGBCombination tools Saturation Transfer function to increase color with the extract L image. The nice thing about this method is the tool has color noise reduction built in if you need it or want to use it.



Mike

[jkmorse]

Mike,

Thanks, that makes perfect sense.   

Jim

[cdesselles]

This LRGB Combination method intrigues me.  I've not attempted that process yet.  Could one of you please give a more complete "step by step" of what you are doing here (and why).
 

[msmythers]

All that is happening is we extract the CIE L* component image from the original RGB image. Use that L image with the LRGBCombination tool. Set the desired color saturation level. Here is the part that I think throws people off, less is more saturation. As we adjust the saturation parameter towards 0 we are increasing the saturation level. It's the math behind the tool I would guess. Then nothing more then applying the tool to our image. Your not creating a new image just acting on the original. The great thing about this method is the built in noise reduction.


Here is a posting about this aspect of the tool. The entire post is good reading.
http://pixinsight.com/forum/index.php?topic=2485.msg16706#msg16706



Mike

[Warhen]

Jim, as Mike says- adding Sat with LRGBC is convenient, and CNR is offered, but while I began this way, I'd strongly recommend avoiding it Adding Sat globally/unmasked increases chrominance noise in the BG and dim areas, which the CNR can't fully make up for. Better to add Sat independently using an L or Range mask. 

[msmythers]

Warren,

I totally agree with using a mask. You can mask your image while increasing the saturation using the LRGB Combination tool in the same way you would with the Color Saturation tool or Curves.


Mike