Photoshop: Spot channels in RGB don't match CMYK (GPU issue)

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  • Updated 6 years ago
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When creating spot channels for offset printing the channels no longer look like they are overprinting/multiplying on top of 4 color art. Instead they look like solid colors or they can be set to transparent, Any way to have the Channels view the way they did in previous versions of photoshop (Cs4 and down) ? The problem is it no longer simulates overprinting.
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Tom Collins

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Posted 6 years ago

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Chris Cox

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Photoshop hasn't changed the way it displays spot channels since around Photoshop 5.0, so I'm not sure what you're referring to.
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Tom Collins

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I'm aware that Cs5 handles them the same way as Cs6, I guess I was wondering if there was a setting to allow them to handle more like Cs4 and down? Not sure why Adobe changed the way they handle? Chris, thank you for taking the time to respond, it is appreciated.
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Chris Cox

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Again, the way spot channels are displayed and handled has not changed since Photoshop 5.0 (15 years ago).

So I'm still not sure what you are seeing.
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Tom Collins

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Okay so i looked into it some more and here is what I'm seeing. With spot channes solidity set to 0% in Cs6 and Cs4 channels are treated the same in CMYK color space, But if you look at how the channels are treated in RGB color space they are different. I have attached 4 screen shots showing the different options. As you can see the bottom two images (cs4) there is no difference. But in Cs6 there is a difference in the channels. The problem is often i need to work in RGB with spot channels before I make the Conversion to CMYK because layer effects work differently in CMYK and RGB
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Chris Cox

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Try turning off the GPU, relaunching CS6, and see if it works as expected.
Again, the actual code and logic hasn't changed - but if there's a driver/shader problem, that might explain the preview difference.
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Tom Collins

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THANKS! that solved the problem
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Chris Cox

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Well, that gives us information - it's not a long term solution.

Now we know that the problem is the GPU code, driver, shaders, etc. - but it might be specific to your configuration.

What OS are you using?
What GPU/video card?
What video driver version?
(you can get these from Photoshop Help->System Info)
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Tom Collins

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Adobe Photoshop Version: 13.0.4 (13.0.4 20130104.r.28 2013/01/04:21:00:00) x64
Operating System: Mac OS 10.7.5
System architecture: Intel CPU Family:6, Model:15, Stepping:6 with MMX, SSE Integer, SSE FP, SSE2, SSE3
Physical processor count: 4
Processor speed: 2660 MHz
Built-in memory: 32768 MB
Free memory: 21425 MB
Memory available to Photoshop: 31752 MB
Memory used by Photoshop: 71 %
Image tile size: 1024K
Image cache levels: 6
OpenGL Drawing: Disabled.
OpenGL Drawing Mode: Advanced
OpenGL Allow Normal Mode: True.
OpenGL Allow Advanced Mode: True.
OpenGL Allow Old GPUs: Not Detected.
OpenCL Version: 1.1 (Aug 10 2012 19:59:48)
OpenGL Version: 2.1
Video Rect Texture Size: 16384
OpenGL Memory: 1002 MB
Video Card Vendor: ATI Technologies Inc.
Video Card Renderer: ATI Radeon HD 5770 OpenGL Engine
Display: 2
Display Depth: 32
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Chris Cox

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Alright, from that we'll see if we can reproduce the problem and narrow down the cause.
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Tom Collins

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Hi Chris, I've actually been dealing with this problem for a while and it was only till one of my employees had the same problem that I started looking for a solution. I just checked about six of our computers all running Cs6, some are newer i macs and 3 older towers with relatively new graphic cards and all have the same problems