Dynamic Range - Colour Balance versus Levels and Colour

[Marpel]

I tried to find the answer to my question in the Help section as well as in the Colour Balance paper but could not find explicit enough language.

I was comparing the resultant Dynamic Range and Colour Balance of an image, obtained through the use of the Levels and Colour and Colour Balance transforms, to determine the most efficient and best method. I started with the same low DR 16 bit TIFF (foggy west coast beach) and applied the workflows, as noted (after the basic RAW workflow, without Colour Balance, in another program):

1 Fully expand the DR via Levels and Colour. Apply the auto Colour Balance transform, without using the full expansion DR buttons.

2 Apply the auto Colour Balance transform, while utilizing the full expansion DR buttons.

3 Out of curiosity, I then took the resultant image from #1 and applied Colour Balance again, while using full DR expansion.

I was surprised to find a noticeable difference in the resultant three images, in both colour balance as well as the darkness of the shadow areas . #1 was lighter in the shadow end and did not match the Colour Balance of #2 and #3. Funny thing, #2 and #3 were similar in DR but the Colour Balance was a bit different.

Up to this point, I have assumed the use of full expansion DR in both transforms would bring the shadow and highlight ends to the same respective points and so believed the workflows would arrive to the same result. I recall being told that the Levels and Colour DR expansion brings the respective ends to black and white, while still maintaing detail, and that is reflected in the Help description of this transform. However, the explanation for full DR in the Colour Balance paper refers to pure black and pure white, with no mention of retaining detail. So my questions:

Is the full expansion DR the same in these two transforms?

If no, what is the purpose of the two methods being different and, which is then the best method to do full DR and Colour Balance?

Regardless of any difference between the two transforms, why would #2 and #3 be different if they both, ultimately, went through full expansion DR in Colour Balance?

Thanks

Marv

[Winfried]

The difference of this tools is:
- Level and Color uses the HSV or the HSL color-model
So this tranformation alters the dynamic range for the Value/Lightness-chanel
The colors and the saturation should not alter.
- Color Balance uses the rgb color-model
So this transformation alters all three chanels, which can result in a shift of the overall colors and saturation

For this reason some photoshopers switch to the Lab-modus and use the L-chanel für adjusting lightness.

I got the best results by using first the Level and Color Transformation and second the Color Balance transformation.

Regards
Winfried

[Marpel]

Thanks Winfried for your explanation.

I too, have traditionally used Levels and Colour to manage the DR of an image and Colour Balance (although with the full DR expansion button not used) to manage the overall Colour Balance. I just figured doing both in C.B. would save a step while still arriving at a somewhat similar result.

I have also used the Lab method, however, am more and more wishing to keep an image in one program for most everything. PWP has slowly become my program of choice.

Having said that, regarding your comment about C.B. altering both colour and saturation, I would have thought saturation would be less (i.e. "not") affected, unless also using the full DR button. Unless that is what you mean....

Anyway, thanks again.

Marv