I know that there have been many discussions and I have been over Sean's tutorial on the subject in fine detail, but ....!! And, because I use the GIMP, I've got the Sinc/Lanczos alogorithms available that Sean suggests produces best results.
This,below, is a pale imitation of the full size image. As you can see in the bottom half, there are lots of leaves on trees. For me, the full size (thanks, I'm sure, to the 70-200f4L IS rather than me) just flys. Every leaf pops and I'm terribly pleased with it.
Taking it down loses so much of the detail and the leaves become just a 'blob' of colour. And, because of that, I think, it loses the contrast that was there and, indeed, seems to alter the colour. I've been blurring and sharpening .. and sharpening and blurring .... and saying naughty words! The full size is 3906 x2602.
How would you re-size to keep as much of the detail as you could? Do you know the secret? Or am I just facing one of the consequences of re-sizing an image such as this for the web?