How to select all 100% transparent pixels in a layer in Photoshop

[colorcafe]

How to select all 100% transparent pixels in a layer in Photoshop

Could someone please list a clear numbered step by step on how to select all 100% transparent pixels in a layer in photoshop only?  I have just one layer in photshop.  It has a cleanly cropped circle on a transparent background.  The circle is not a solid color, but it is many colors of various opacities.  I don't want to select any of the colors in the circle, just the 100% transparent pixels around it. 

Trying these solutions did not work:

1.  Using the magic wand tool to click on the transparent pixels doesn't work for me.  Since the circle has some semi-opaque pixels, it messes it up.

2.  I thought I could hold ctrl and click on the thumbnail image in the layers panel to select all colored pixels and then inverse to select all transparent pixels.  However, this doesn't work either.  Ctrl clicking on the thumbnail image in the layers panel doesn't select all colored pixels since some colored pixels are only semi-opaque.

[Nancy OShea]

Show us the picture please.  And also post a screenshot of your workspace showing the magic wand Sample Size and Tolerance level.

Depending on the image, you might get more precise results with a selection mask.

[Semaphoric · Accepted solution]

Your second method will work, with a couple more steps. Once you have the inverted selection, enter Quickmask mode, and Image > Adjustments > Threshold, with a value of 255, on the Quickmask channel. Exit Quickmask, and you will have all the 100% transparent pixels selected.

[planetboris]

Thanks very much, this helped tremendously, excellent tip! Saved me hours of time. Cheers!