Thresholding selection tool

JR
Posted By
John_R_Davies
Feb 6, 2007
Views
245
Replies
3
Status
Closed
Windows XP. Photoshop 6.0

Can anyone help. Is there a way of selecting from a canvas only areas below a certain greyscale threshold?

I have some medical images which are on a greycale with white being 255 and black being 0. I want to highlight only areas that are below 145.

Thanks in advance.
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CB
charles badland
Feb 6, 2007
What if you made an Threshold Adjustment layer (to preserve image) set to 145, then Cntrl+Click on the Gray Channel (or RGB Composite Channel) to select the pixels?
JR
John_R_Nielsen
Feb 6, 2007
I would load the luminance as a selection first, and then use Threshold in Quickmask Mode.
CB
charles badland
Feb 6, 2007
I would load the luminance as a selection first, and then use Threshold in Quickmask Mode.

Huh. For some reson that method does not select from 145 and under when I tried it on a White to Black Gradient.

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