4. Swap over to the blue channel, by either clicking the channel in the Channels palette or using the keyboard shortcut Cmd/Ctrl + 4. Select the blue channel within the Curves dialog box. Perform the same adjustment, starting by creating a center point on the curve, and dragging until the mid-tones in your image match those in the target.
Curves adjustments for the blue channel
5. Repeat these adjustments for the green channel. Click the green channel in the Channels palette or use the keyboard shortcut Cmd/Ctrl + 5.
Smashing eBook #8│Mastering Photoshop for Web Design, Volume 2 │ 149