- Flatten your layout page
- Resize it to 600px x 600px (most online galleries go with this size) at 300dpi
- Control-J to copy the image on a new layer
- Activate the new layer, then go to topline menu bar. Select Fliter>High Pass>Radius o.3px (or somewhere there, play with it for each image)
- Image will turn almost solid grey - don't panic!
- Change the blending mode of the layer to "Linear Light"
- Save for web > jpeg, under a different name.
Don't do this to your full-size pages that you wish to print out though. It only works well for web-viewing.
Hope this helps you a bit :)