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AmazingFactory
Joined: 30 Mar 2013
Posts: 5
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 Posted: Sat Mar 30, 2013 3:07 am Post subject: Linear Gradient not Linear |
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Create an image 256 pixels wide
Using RGB Black and White
Stretch a gradient from X = 0 to X = 255
The color in each pixel should increment by 1
0, 1, 2, 3, 4, ...
Which it does in every other image manipulation program I have ...
But in Photoshop the darks are more stretched out:
0, 1, 2, 2, 3, 3, 4, 4
and the mid-range skips some colors:
128,130
The pixel with X = 128 has RGB = 128
Any ideas? |
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SCTRWD
Joined: 20 Jul 2011
Posts: 79
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| Posted: Sat Mar 30, 2013 6:48 am Post subject: |
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PS does not make mathematically precise gradients. To every gradient PS creates it applies S curve. You can see it by historgam. As a result there are missed and doubled values along the gradient. Adobe thinks this is just what you want. Looks good, but for some adjustments it's not good at all.
One way to make clean black to white gradient:
Make Index color mode document, go to Image->Mode->Color Table dialog, choose Grayscale pallete and save it as a ACT file on disc. Find this file on disc and change it's extension to RAW.
Now open this file as raw image in PS. In Open dialog set Width - 256, Height - 1, Inteleaved - checked.
Now change the size of this image to 256x256 with Image->Image Size. |
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AmazingFactory
Joined: 30 Mar 2013
Posts: 5
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| Posted: Sat Mar 30, 2013 7:49 am Post subject: |
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Thanks so much
I couldn't think of a reason for that S curve
Illustrator is blighted in a similar way |
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SCTRWD
Joined: 20 Jul 2011
Posts: 79
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| Posted: Sat Mar 30, 2013 9:22 am Post subject: |
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Me neither!
That's one of the terrible things Adobe does behind our backs!
After all, if I ever wanted an S-curved gradient, I would do it myself!
But, please, don't do it if I'd never asked for it!
I know much better what is right for me, and what I REALLY want!
If I make a gradient, I want it to be just what I want it to be: no more, no less!
But it looks like guys in Adobe have something else in mind...  |
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AmazingFactory
Joined: 30 Mar 2013
Posts: 5
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| Posted: Mon Apr 01, 2013 3:27 am Post subject: |
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In the Gradient Editor you can set Smoothness to 0%
Then you will get Linear Gradient |
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SCTRWD
Joined: 20 Jul 2011
Posts: 79
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| Posted: Mon Apr 01, 2013 5:17 am Post subject: |
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Hey, that's great!!!
AmazingFactory, your really "Amazing"! |
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