affinity photo LAB color space for subtle colors and greys without colorcast

[unni]

During processing, I wanted to bring out the range of tones in the clouds along with its subtle orange color patches. In RGB color space, the results were not so good.
So the complete processing was done in LAB. In the develop persona, tone curve and noise correction was disabled.
In shadows and Highilights, Highlights slider was brought to -100%.Then brightness, blackpoint and exposure was slightly changed.
Clicked "Develop" and image was brought to Photo persona. Document color space was changed from RGB to LAB.
First applied Filters>noise>Dust&Scratches to the A&B channels for removing the color noise.Then denoise applied in L Channel.
Now From Adjustment tab, Curves was selected. In panel, LAB was selected. Then Lightness. Adjusted the curve to increase
the contrast and bring out the desired effect on the clouds.This made the foreground and buildings very dark but it was
ignored(mask will be used later).Then adjust the A channel to bring out the orange and golden shades in the clouds.
B channel was not adjusted.Now make a mask which has white color for the clouds and black for the remaining foreground.
Initially itself, after denoise, the layer was duplicated. Now the second layer was selected and curves was adjusted in the L channel
and A channel giving importance only to the building, road, trees,grass (ignore clouds). The mask selects the clouds from the first
layer and rest of image was from second layer. Merge all layers , convert back to RGB color space and export.

The file was exported to JPG full size. I used RIOT standalone free software for downsizing to 1800 pixels because AP downsized JPG
file looked little blurred. AP shows no quality problem when exported to JPG in full size.

Picture shot in Nikon D3100 at 400ISO, 18mm kit lens, 1/80sec and f4.5. Due to the low f number, the sharpness is not so good.

LAB color space was able to keep the clouds and other neutral areas grey whereas RGB makes it slightly bluish. The grass also has good green color.