My edit of by pjotre7 for post-processing side challenge.
-Channel Mixer > monochrome mode
-RGB Curve
-RGB Curve
-Save to grayscale
-Create graduated bilinear mask along treeline
-Curve to forest area through mask
-Curve to background through inverted mask
-Convert to Tri-Tone: Black, Cool Gray 8, Cyan
-Convert to RGB
-Resize
-Crop a little top/bottom
-USM at 66%/0.6 dia/TH = 5 (applied twice)
-SaveAs JPEG at quality 10/10 = 310KB