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Author Topic: Gradient tool linearity in PS (is driving me slightly insane)  (Read 1305 times)

shewhorn

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Gradient tool linearity in PS (is driving me slightly insane)
« on: September 25, 2010, 04:40:58 pm »

This is driving me NUTS! I'm trying to create a black to white gradient for monitor testing purposes. I figure, great... 256 discrete values in 8 bits, if I multiply that by 3 I get 768 so there's my horizontal resolution and vertical... let's say 150. So 768x150 pixels. Good. I go to create a new document which is NOT color managed (RGB, 8 bits). I hit the 'D' key to set foreground/background to black/white. I hit G for the gradient tool. I turn off dithering, I make sure the linear gradient is selected, I zoom in to pixel level and holding the shift key to keep the line perfectly horizontal I click on the far left of the file and then drag to the far right being careful to be perfectly lined up with the right edge and release the mouse.

Now... what I expect to have is a gradient from left to right where the density changes every 3 pixels and this should result in a histogram that is a perfectly flat line. Unfortunately it bears more of a resemblance to a half pipe.. The first 3 should be 0,0,0; the next three should be 1,1,1; after that 2,2,2; and so on. That is NOT what I get. What I get is... pixels 0 through 2 are 0,0,0 (so far so good, but then it goes off), pixels 3 through 8 are 1,1,1; pixels 9 through 13 are 2,2,2 (and now it really goes HORRIBLY wrong), pixel 14 is 2,2,3.  :-[ :-[ :-[, pixels 15 through 19 are 3,3,3....

OY!!!!

I'm wondering why the gradient looks wrong and well... it is! Heck it's not even neutral. I figure this is a PEBKAC error but if it is, I can't figure out what's wrong with me. Any ideas?

Cheers, Joe
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shewhorn

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Re: Gradient tool linearity in PS (is driving me slightly insane)
« Reply #1 on: September 25, 2010, 05:22:00 pm »

Total PEBKAC error.  ;D

The smoothness needs to be dialed down to 0.

Cheers, Joe
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Jeremy Roussak

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Re: Gradient tool linearity in PS (is driving me slightly insane)
« Reply #2 on: September 26, 2010, 07:44:07 am »

Total PEBKAC error. 
Forgive my ignorance and enlighten me. PEBKAC?

Jeremy
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TimBarker

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Re: Gradient tool linearity in PS (is driving me slightly insane)
« Reply #3 on: September 26, 2010, 07:52:31 am »

do a google search - several excellent cartoons,
Problem Exists Between Keyboard And Chair.
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Tim Barker (aka MandoTiM in other forums),
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