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Archive 2013 · Threshold adjustment layer / clipping mask not working co...
  
 
jzucker
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p.1 #1 · p.1 #1 · Threshold adjustment layer / clipping mask not working correctly in CS6


This is a repeatable problem with images from my canon 5d, 8 bit adobeRGB.

What i've been doing is adding a layer of noise and then using a threshold adjustment layer and a clipping mask on the threshold layer. I then adjust the threshold until I get the level of dots/noise that I want. So far so good. However, if I then save the image and view it in lightroom or render the image, I get a different level of noise then what I'm seeing in photoshop even using "actual pixels" and rendering at full size.

Very odd.

The other thing I notice is that if instead of using a clipped adjustment layer, if I instead apply the threshold layer directly to the noise layer, the preview looks *TOTALLY* different than the result when I press OK.



Jan 19, 2013 at 04:06 PM
Eyeball
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p.1 #2 · p.1 #2 · Threshold adjustment layer / clipping mask not working correctly in CS6


I think this combination of adjustments is obscure enough that you are going to have to provide more detail if you want us to try to replicate it. For example, I just tried it in PS with the following layers in AdobeRGB, 8-bit:

L3 - Threshold layer with clipping mask (Threshold level 142)
L2 - 50% gray layer with monocramatic noise applied (70%, Gaussian, Mono) in Overlay mode
L1 - Image layer as imported from ACR

I saved this as a TIF without layers, brought it back into PS and compared to original. They looked the same to me.

I also tried the "Threshold as adjustment layer" vs. "Threshold directly on noise layer" and I obtained exactly the same results (verified with difference blend mode).

As you imply in your post, looking at the image using "actual pixels" is absolutely critical to avoid any interpolation effects from the screen display process.

If you are saving to Jpeg, that might introduce some changes.

There may be something happening with your video card and the video card acceleration features of PS but I would not expect that to impact Actual Pixels either.

I'm stumped. If you can provide more detail about your exact steps, I will try to reproduce.



Jan 19, 2013 at 05:00 PM
jzucker
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p.1 #3 · p.1 #3 · Threshold adjustment layer / clipping mask not working correctly in CS6


Thanks for the reply/help! Here are the steps. Running on CS6

1) new image 3744x5618, 8 bit, adobe RGB (same specs as canon 5d)
2) fill with black
3) Filter->Noise->Add Noise (103,Gaussian,Mono)
4) add threshold adjustment layer, level 103
5) Save as jpg, quality 10
6) Load jpg, compare to PSD image

and a similar thing happens if you apply the threshold directly to the layer except this time, the preview doesn't match the final result.

Here's a link to both files in photoshop.

http://www.jackzucker.com/images/threshold-example.jpg



Jan 19, 2013 at 05:46 PM
Eyeball
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p.1 #4 · p.1 #4 · Threshold adjustment layer / clipping mask not working correctly in CS6


OK, well regarding what you show in your second post, there can indeed be differences in what appears on your display screen when at less than Actual Pixels when using layers. Photoshop uses certain display shortcuts in this scenario for what I assume are performance reasons. When you are doing an operation at the fine pixel level like you are doing these differences can be significant.

In these situations, you really need to be viewing and comparing at Actual Pixels. It's not exactly Adobe's fault for this either. Anytime you are viewing an image at less than 100% zoom (Actual Pixels), compromises need to be made regarding how that image is shown on screen. You can say "well at least Adobe should make the flattened vs. layers view look the same" and I can understand that to a point but consider that there are performance issues that Adobe has to contend with when displaying multiple layers and neither preview is "absolutely correct" with respect to how the image will look at full resolution/Actual Pixels.

Now beyond that, I thought you were saying you were seeing differences at Actual Pixels between original and saved or between one application and another. Is that the case?

Also, at some point it might be a good idea to explain what you are trying to do and why. For example, I question whether Threshold is the best way to accomplish what you are trying to do. When you use the Threshold adjustment in this scenario, you are changing grayscale noise automatically to full-black and full-white noise. It makes a major change to the characteristic of the noise beyond what appears from a distance to be a simple noise "volume" adjustment. I suspect something like Curves may work better for you but you're the one who knows what you're trying to achieve.



Jan 19, 2013 at 06:56 PM
jzucker
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p.1 #5 · p.1 #5 · Threshold adjustment layer / clipping mask not working correctly in CS6


no, it's different at actual pixels, not just screen display as I stated before.


Jan 19, 2013 at 07:24 PM
Eyeball
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p.1 #6 · p.1 #6 · Threshold adjustment layer / clipping mask not working correctly in CS6


OK, here are my results trying to reproduce your steps as listed. All crops shown are at 100% zoom/Actual Pixels and are saved for display here in either GIF or PNG to try to avoid the introduction of additional artifacts. Simple refers to images where Threshold was applied directly to the noise layer. Layered refers to images where Threshold was applied as an adjustment layer.

Just as a reminder, Add Noise is one of Photoshop's random rendering filters and it will not produce the same exact pattern from one use to the next. Still, to my eyes, the over-all effect in these tests appears to be the same to me.

Originals, simple vs. layered, side-by-side

http://dl.dropbox.com/u/12145446/NoiseThresh1.gif

Original simple vs Jpeg simple

http://dl.dropbox.com/u/12145446/SimplePSDJpg.png

Original layered vs. Jpeg layered

http://dl.dropbox.com/u/12145446/LayeredPSDJpg.png

Jpeg simple vs. Jpeg layered

http://dl.dropbox.com/u/12145446/SimpVsLayJpegs.png



Jan 19, 2013 at 08:08 PM
jzucker
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p.1 #7 · p.1 #7 · Threshold adjustment layer / clipping mask not working correctly in CS6


not sure what's going on but my issue is 100% reproduceable.


Jan 19, 2013 at 08:19 PM
Eyeball
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p.1 #8 · p.1 #8 · Threshold adjustment layer / clipping mask not working correctly in CS6


Could you post comparisons at Actual Pixels so we could try to see what you're seeing?


Jan 19, 2013 at 08:35 PM
jzucker
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p.1 #9 · p.1 #9 · Threshold adjustment layer / clipping mask not working correctly in CS6


you can see what i'm seeing in the composite I linked to. Both images are the same size and are zoomed to the same level. Am I just missing something in the way the threshold algorithm works?


Jan 19, 2013 at 10:48 PM
 

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Eyeball
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p.1 #10 · p.1 #10 · Threshold adjustment layer / clipping mask not working correctly in CS6


All I am seeing is the screen image of the two images compared at a 16.7% zoom level. I would like to see them at 100% (Actual Pixels). I am also not sure if the PSD shown in that screen image is the one where you applied Threshold directly or by a Threshold adjustment layer.


Jan 19, 2013 at 11:52 PM
WAYCOOL
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p.1 #11 · p.1 #11 · Threshold adjustment layer / clipping mask not working correctly in CS6


Where did the psd come from are you sure it was created in the same way?


Jan 20, 2013 at 02:18 AM
jzucker
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p.1 #12 · p.1 #12 · Threshold adjustment layer / clipping mask not working correctly in CS6


yes, i created it. That's the whole point of the issue.


Jan 20, 2013 at 02:21 AM
Eyeball
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p.1 #13 · p.1 #13 · Threshold adjustment layer / clipping mask not working correctly in CS6


Just to demonstrate how PS produces different results at less than 100% zoom for flattened and unflattened adjustments:

This first screen image compares your noise process with the Threshold applied directly vs. the noise process with the Threshold applied via an adjustment layer, which is unflattened. There is a noticeable difference.

http://dl.dropbox.com/u/12145446/SimpVsUnflat.gif

This second screen image is the same thing but with the Threshold layer on the right having been flattened. There is no significant difference.

http://dl.dropbox.com/u/12145446/SimpVsFlat.gif

Changing the cache levels, cache tile size, and/or Graphics Processor Settings in Photoshop performance preferences MAY have an impact on this behavior but I have not tried and compared all the permutations to verify.



Jan 20, 2013 at 03:25 AM
Mr Mouse
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p.1 #14 · p.1 #14 · Threshold adjustment layer / clipping mask not working correctly in CS6


Did you run the action I created and compare the results at actial pixels. To me it looks like the threshold adjustment layer in your zoomed out display is not being displayed correctly; It should look like your jpeg. Please view both document at actual pixels. Save the PSD close it and reopen it. I think the view your seeing for the PSD is wrong.

http://www.mouseprints.net/old/dpr/Test.atn This action expects a c:\temp\ to save the jpeg and then be opened. The action will display the PSD and Jpeg at 100%



Jan 20, 2013 at 03:28 AM
jzucker
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p.1 #15 · p.1 #15 · Threshold adjustment layer / clipping mask not working correctly in CS6


Yes, at actual pixels they look similar but not identical. The pattern is different. I think eyeball nailed it. There seems to be a bug in the way the threshold adjustment layer preview works at zoomed out levels. The same bug seems to exist in the preview window of the image->adjustment->threshold when you are zoomed out.

One thing this brings out is that there is no way to accomplish what I want to do with an image of this size and a threshold layer. What works instead is gaussian blur, levels, gaussian blur, levels, threshold.

I'll post an example layer. Gotta get ready for a portrait session.



Jan 20, 2013 at 02:41 PM
Mr Mouse
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p.1 #16 · p.1 #16 · Threshold adjustment layer / clipping mask not working correctly in CS6


Try resetting your Photoshop preferences for they are identical on my machine.


Jan 20, 2013 at 03:15 PM
jzucker
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p.1 #17 · p.1 #17 · Threshold adjustment layer / clipping mask not working correctly in CS6


ok, i'll try that but i have the same issue running on my notebook computer so I don't think it's particular to this machine's prefs.

Anyway, a better way to accomplish what I want is this and it works at high res.

Make layer
Fill
Using: foreground color
Add Noise
Distribution: gaussian
Percent: 150%
With Monochromatic
5568165
Gaussian Blur
Radius: 5 pixels
Levels
Preset Kind: Custom
Adjustment: levels adjustment list
levels adjustment
Channel: composite channel
Input: 103, 112
Gaussian Blur
Radius: 5 pixels
Levels
Preset Kind: Custom
Adjustment: levels adjustment list
levels adjustment
Channel: composite channel
Input: 125, 158



Jan 20, 2013 at 03:31 PM
Alan321
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p.1 #18 · p.1 #18 · Threshold adjustment layer / clipping mask not working correctly in CS6


You lost me when you mentioned "layer"


Jan 21, 2013 at 06:47 AM





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