Why your greens look flat

A hillside on screen has a dozen distinguishable greens in it: new growth, old leaf, shadowed leaf, grass, moss, the yellow-green of a different species. In a badly adjusted file it has one.

The mechanism

Foliage sits in a narrow band of hue. What separates one green from another in a real scene is mostly luminance and a small amount of hue variation, not saturation.

When you raise global saturation, you push every one of those greens toward the same fully saturated value. The differences that were carrying the information get compressed out, and you are left with a flat green mass that looks vivid and reads as artificial.

The image gets more colourful and less legible at the same time, which is why it looks wrong without looking obviously wrong.

What to adjust instead

Luminance separation. Lighten the yellow-greens slightly and darken the blue-greens, or the reverse. This restores the difference between species and between lit and shaded foliage without touching saturation at all.

Targeted hue. Pull the yellows a little away from the greens. In most temperate scenes this single move does more than any other, because new growth and grasses live in the yellow-green range and mature leaf does not.

Local contrast, gently. A small amount at a medium radius gives leaf clusters back their shape. Too much and every leaf edge halos.

Why print makes it worse

Most print processes compress the yellow-green range considerably more than a screen does. A hillside that shows clear separation on a monitor can flatten into one green on paper even when the file is fine.

Soft-proof with the actual paper profile and look specifically for that flattening. Where it happens, the fix is the same as above: increase luminance separation, not saturation, before conversion.

The white balance trap

Green casts are easy to introduce and hard to see, because the eye adapts. A frame shot under a leaf canopy has genuinely green light in it, and correcting it fully makes the scene look like it was photographed somewhere else.

Correct partially. Leave some of the cast; it is what makes woodland look like woodland.

Check against a neutral

The most reliable habit is to find something in the frame that should be grey - rock, a path, weathered wood, cloud - and check it is neutral. If the greens look right and the rock is green, the greens are not right; you have adapted.