Digital Light & Color

An interesting observation: a RAW image taken in artificial light shows quite yellow when 'opened' from a RAW file. As expected as there is no WB used.

The Color Balance does the trick removing the tint more or less automatically while more or less preserving the dynamic range of its input image (even without using its Full Range option).

I also tried Levels and Color to do the same thing (by clicking on neutral parts). A lot of blue has been added to balance the yellow tint, but now the image's dynamic range is much narrower. However, the Dynamic Range slider ticks still show the original (yellow) dynamic range as extending to (almost) full range. Inserting the second Levels and Color transformation below the first one shows the proper (i.e. reduced) dynamic range of its input and its Dynamic Range slider can be used again to stretch the image brightness to a full range.

p.s. It seems also possible to click on the Output Preview image to select the Levels and Color's Color Balance color, in which case a weird cascade of color corrections can be seen.

p.s.s. In Adjust transformation, Color tab, Remove color cast seems to preserve the dynamic range of the image (unlike Levels and Color).

Maybe Color Balance is a poor name for what Levels and Color does. The operations in Levels and Color are performed in a certain order. The Color Balance operation is performed after the brightness changes so it does not interact with the dynamic range controls. When it does is apply a color cast to the image rather than doing a white balance, so maybe it should be called Color Cast instead of Color Balance. I could potentially add an auto-white balance checkbox to Levels and Color.

If you decide to add an auto-white balance checkbox, that can be actually helpful as the other 'Swiss-army knife' application - the Adjust - requires a bit more thought to apply quickly and correctly.

Would auto-white balance work in a similar fashion as the Colour Balance? And if it's implemented, how could it work best in batch: auto-adjusting each image in the batch, or learning from the first one and applying it to the rest of them?

If implemented, it would have to auto-adjust every time. Have not had a chance to look at this yet -- possibly something in the Settings menu to let you auto white balance and/or auto range when the transformation starts up.

If you are looking for a transformation to blindly auto-correct raw images, maybe adding auto white/black balance as an option to the Autorange transformation would be a better way to go.

I can't think of a way to add white balance to Levels and Color that would not be confusing since it already has a color balance setting and the whole idea of Levels and Color is to keep it as simple as possible. If I change the was the existing color balance setting works, it will invalidate any existing scripts that use it.

It's all good. The reason I mentioned it was that I was surprised how the Levels and Color's Color balance reduced the dynamic range without slider showing it - but you've explained already. Stacking one Levels and Color after another does the trick, as so does Colour Banace and Adjust. I forgot about Autorange, which is probably the best for blind RAW adjustments. Thanks!