While Photoshop is absolutely packed with bells and whistles, there are a few key tools to unlocking its full potential. The Quick Mask feature in Photoshop is one of them. Quick Mask is essentially a selection tool on steroids. It allows one to select down to the pixel a given area of a photo. While there are many uses for selection to alter color, sharpness and other effects, a very common use is to knock-out a background around an object.
Step 1. Select the background
WIth the shift key click areas of the background that you want to knock-out. The more contrast between the background and the subject the better. In some cases, such as this image the contrast is low so we’ll need to use Quick Mask to do the finer selection.
Step 2. Enter Quick Mask Mode
Notice the icon second from the bottom in the toolbar. This is the Quick Mask toggle button. When in Quick Mask the icon has a darker parameter. It is clear at this point that some of the guitar was selected with the background.
Step 3. Paint the object
To get a very precise selection, zoom-in to get a close-up of the area to be selected. Choose the paint brush to color every area not selected. In this case we want to knock-out the background so the guitar will be painted.
Zoom-out and review for any rough spots. I find using a larger brush tends to create a smoother line as I drag it along the edge of the object.
Step 4. Switch Back to Regular Mode and Inverse Selection
One can either delete the background or choose to inverse selection to the object.
Step 5. Copy and Paste into New Window
I often prefer to paste the object into a new window so as to leave the original image in tact.
Step 6. Delete Background Layer and Save as .PNG
Finished Image
If you prefer resize, rotate image or apply other affects, upload and enjoy. Let me know if you have any questions and if this tutorial was helpful.