WOW - a completely new way of adjusting images

A

AncientSnapper

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153
Name
Chris
Edit My Images
Yes
Hi,

Jacob Rus has invented a new way of color-correcting images in Photoshop (would probably work in GIMP too), that is intuitive and easy to do.

I was so impressed I thought I'd write it up and share it with you.

Have a peek http://www.broadhurst-family.co.uk/lefteye/MainPages/jacobsladder.htm

I've included some PS actions so that you can experiment.
 
looks interesting will try it out thanks :)
 
A word of caution with this, converting to LAB mode is claimed to be distructive by some due to rounding errors in the conversion to LAB and back, I'd advise you use 16 bit if you are doing this to minimise any quality lose however small. Wayne
 
Dan Margulis, the guru of post-processing, says you should not worry about this as 16bit processing is a bit over the top.
He claims you can not tell the difference between 8 & 16bit rgb>lab>rgb. Can you give us an example Wayne?

The other point to notice about this technique is that it is now possible to set multiple neutral points in lab mode - something that everybody said was impossible!

Lastly I would advise people to try Lab processing as it is much better than rgb on a number of types of images - You will be amazed at what can be done quickly and easily in lab that is virtually impossible in rgb. Read Dan's book "Photoshop Lab Color" if you want to understand post-processing and colour.

Here is an example of colour saturation in rgb & lab - just notice the artifacts in rgb!
SunsetrgbCrop.jpg
and
SunsetlabCrop.jpg

- see http://www.broadhurst-family.co.uk/lefteye/MainPages/saturation.htm for another example and how to do it
 
AncientSnapper said:
Dan Margulis, the guru of post-processing, says you should not worry about this as 16bit processing is a bit over the top.
He claims you can not tell the difference between 8 & 16bit rgb>lab>rgb. Can you give us an example Wayne?

The other point to notice about this technique is that it is now possible to set multiple neutral points in lab mode - something that everybody said was impossible!

Lastly I would advise people to try Lab processing as it is much better than rgb on a number of types of images - You will be amazed at what can be done quickly and easily in lab that is virtually impossible in rgb. Read Dan's book "Photoshop Lab Color" if you want to understand post-processing and colour.

Here is an example of colour saturation in rgb & lab - just notice the artifacts in rgb!
SunsetrgbCrop.jpg
and
SunsetlabCrop.jpg

- see http://www.broadhurst-family.co.uk/lefteye/MainPages/saturation.htm for another example and how to do it
Click to expand...

Dan is a controversal figure, everything he says is law, right or wrong, on some serious forums just mentioning his name will start a riot, fortunatly not here (more sensible) However he's considered by many of the serious people to be wrong on his "lossles LAB" ideas, in the real world you would probably be hard put to see any difference though, but if your after top quailty I'd recomend 16 bit. Wayne
 
Hmm... interesting but there are more exotic ways to hack colours around. When I really need to get creative I normally reach for my 3D app, take everything into 64bit per channel colour (that's gazillion of colours with real HDR) and chuck a bit of shader code at the problem :geek:

It also works for other stuff too, like using UV mapping to correct perspective distortion (y)
 
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