Please make sure to use the images of the following sizes (in px).
Halcyon Slider: 1400 X 500
Halcyon Slider Thumb: 160 X 90
Halcyon Featured Post: 360 X 290
Halcyon Recent Post: 360 X 160
Halcyon Widget Post: 320 X 320
Halcyon With Sidebar: 750 X 450
Halcyon Without Sidebar: 1170 X 450
Halcyon Schema: 600 X 60