You can create a pixel selection using colour, tonal or transparency (alpha/opacity) ranges from your image.
If you decide to create a selection based on any range, your image is analysed and all pixels which fall into the chosen range are included in the selection. Pixels which are not in the chosen range are excluded.
Colour, tonal and transparency range selections are available from the Select menu. These include:
From the Colour Range sub-menu:
From the Tonal Range sub-menu:
From the Alpha Range sub-menu:
Select Fully Transparent—only pixels which have an opacity of 0% are selected.
Select Partially Transparent—all pixels with a transparency higher than 0% are selected.
Select Opaque—only pixels that are 0% transparent are selected.