Knock out logo background
A quick tip if you need to knock out an even colored background of logo's or images found on the net with nice clean edges.
Open your image in Photoshop.
First make sure the image is in RGB mode.
Go to: Image > Mode > RGB color
Then make the layer independent by double-clicking it in the layers window.
With one of the selection tools, select a portion of the background color.
Go to: Select > Similar
And all of the background pixels are selected.
Hit delete on the keyboard and you have a nice clean logo with perfect edges.
If the text in the logo is the same color as the background, go in quickmask-mode and paint in the text.