Gradient Problems

[SignStudent]

I'm trying to print a grey to black radial gradient on a roland versacamm sp540i and it's coming out strange. There are alternating light and dark rings showing up. I've tried changing profiles (using versaworks), rendering intents, 16 bit gradients dithered to 8 bit, and I'm not sure what else to try at this point.

The first pic is what's coming out of the printer and the second is the art.

Any ideas what to do?

 

[SignStudent]

I've improved the results considerably but there's still room for improvement.

I changed from Pre-Press U.S. to Sign&Display and from my concept 201 profile to oracal 3651. Also I'm using a vector rgb gradient instead of a .tif from photoshop.

Anything else I can do to perfect it?

 

[P Wagner]

Versaworks cannot render 16-bpp RGB files to my knowledge, only 8-bpp files are supported in that RIP. I woudl expect that a raster RGB file from Photoshop (where the same RGB working space is being used throughout the workflow) would yield the most consistent result for a gradient-related output issue.

 

[JoshLoring]

Your problem is that your versaworks profiling is wrong. Sign and display? PrePress? What do these have to do with Adobe files? Nothing..

You should be setting your icc to adobe 1998 and matching your adobe suite color settings to that. Then, versaworks can understand your file..

 

[JoshLoring]

I'm not at my computer- but I screenshot via VNC and this is what you should have set it versaworks..

 

[Custom_Grafx]

This goes in depth and answers a lot of questions. It has worked for me.

http://trojankitten.posterous.com/archive/8/2011?page=4

 

[SignStudent]

Versaworks cannot render 16-bpp RGB files to my knowledge, only 8-bpp files are supported in that RIP. I woudl expect that a raster RGB file from Photoshop (where the same RGB working space is being used throughout the workflow) would yield the most consistent result for a gradient-related output issue.

Take a look at the link Custom_Grafx posted and you'll see what I meant. You start with a 16 bpp and save it down to 8 bpp with dithering to add noise and hide the banding.

I found that in a different post and tried but it didn't resolve the issue. The problem I'm having isn't the same as the banding that it solves.

 

[Custom_Grafx]

Take a look at the link Custom_Grafx posted and you'll see what I meant. You start with a 16 bpp and save it down to 8 bpp with dithering to add noise and hide the banding.

I found that in a different post and tried but it didn't resolve the issue. The problem I'm having isn't the same as the banding that it solves.

It's not simply about saving it down to 8bit with dithering.

Follow the instructions, especially the creating a white noise layer part. This is the part that hides the banding.

A quicker way is to just use the add noise filter as well, but the link's method is better IMO.

Care to upload the problem file or a sample with a similar issue?

 

[SignStudent]

Your problem is that your versaworks profiling is wrong. Sign and display? PrePress? What do these have to do with Adobe files? Nothing..

You should be setting your icc to adobe 1998 and matching your adobe suite color settings to that. Then, versaworks can understand your file..

I'm not at my computer- but I screenshot via VNC and this is what you should have set it versaworks..

You've got me confused now. I'm not sure if I understand what the box that says "use embedded ICC profile" does. Is it referring to the adobe1998, us web coated swop, sRGB, etc. settings or to media profiles? The way I thought it worked, which may certainly be wrong, is that because you're using the embedded ICC profile then the rest of the settings you have screen-shot will be ignored.

This would mean your Adobe and VersaWorks settings don't have to match because it's not using both of them. If you tell it to use the embedded profile it uses Adobe's settings; if you tell it not to it will use VersaWorks' settings.

Also, I see you're using Perceptual for both vector and raster. I've always seen it recommended to use Relative Colorimetric for vector. I'm curious why you have it set that way.

I'm not sure why you say Sign & Display and PrePress have nothing to do with Adobe files. They're just different ICC profiles which affect the color space from what I understand. Sign & Display has a larger gamut.

 

[Custom_Grafx]

Colorimetric can cause banding. When re-mapping colours, it will leave in gamut colours as is, and shift out of gamut to the nearest possible. This can cause a noticeable jump in shades.

Perceptual will maintain the relative shading and shift all colours as required to recreate the tonal gradient required of your graphic, without banding.

Depending on what your particular problem here is, changing to perceptual could solve your problem.

Can you by any chance see that banding on your screen when you turn dithering off in your colour settings in PS?

 

[Northern Design]

Bring the gradient background in to photoshop and add a gaussian blur about 2.0. Then add your art work and send to versaworks

 

[SignStudent]

It's not simply about saving it down to 8bit with dithering.

Follow the instructions, especially the creating a white noise layer part. This is the part that hides the banding.

A quicker way is to just use the add noise filter as well, but the link's method is better IMO.

Care to upload the problem file or a sample with a similar issue?

I think you may be incorrect about the dithering.

FTFA: The correct solution? Dithering. Just like converting from RGB image to Indexed image, dithering 16 bit data to 8 bit will provide a smooth 8 bit representation of the 16 bit color shades, to avoid banding.

The reason they go into creating the white noise layer is for two things: 1) it allows you to have a banding-free preview while working in 16 bit and 2) it gives you slightly more control over the amount of dithering. The small amount of extra control in this context however seems next to useless and I don't really need realtime previews on such a simple file.

 

[SignStudent]

Colorimetric can cause banding. When re-mapping colours, it will leave in gamut colours as is, and shift out of gamut to the nearest possible. This can cause a noticeable jump in shades.

Can you by any chance see that banding on your screen when you turn dithering off in your colour settings in PS?

No I don't see any strange light to dark to light bands on the screen no matter what settings I've used. That only shows up from the printer.

I definitely see the potential problem from using relative colorimetric for gradients and will change that to see if it fixes it.

 

[SignStudent]

Anyone have any thoughts on the "Preserve Primary Colors" setting? I've seen some people recommend it but I'm not really sure what it does. Is it only good in some situations but bad in others? If so, when should it be used?

Thanks for all the input thus far!

 

[Custom_Grafx]

I have successfully eliminated banding in a photograph in the past with this method, so it worked for that particular scenario, BUT, that was with an 8 bit file where I could actually see the banding on my screen, not just on the print, which is why I asked if you could see it on your screen.

If you open your graphic in PS, and you squeeze your levels together, can you see the banding exaggerated? Or is the screen version 100% fine and you only see it in your print? If only in your print, it's a profile/intent issue. If you see it on your screen as well when exaggerating your levels/contrast, you will need to address that first.

 

[Custom_Grafx]

Anyone have any thoughts on the "Preserve Primary Colors" setting? I've seen some people recommend it but I'm not really sure what it does. Is it only good in some situations but bad in others? If so, when should it be used?

Thanks for all the input thus far!

Where you use K100 for example, it will attempt to use K100 in VW. Good for using Y100 sometimes when you quickly need to avoid using "dirty" yellows...

In general I don't use it. It can also be used as a quick way to force only the K channel to be used on your printer... however trying to print greyscale photos with this will result in grainier prints (although it will only use the K ink).

 

[SignStudent]

If you open your graphic in PS, and you squeeze your levels together, can you see the banding exaggerated? Or is the screen version 100% fine and you only see it in your print? If only in your print, it's a profile/intent issue. If you see it on your screen as well when exaggerating your levels/contrast, you will need to address that first.

Nah even if I squeeze the levels I don't get the same kind of banding. I made an exaggerated pic so you can see what I'm talking about. The dithering/white noise would fix the pic on the left but not the one on the right, which is my problem. And yeah the more I mess with it I can tell it's gotta be a profile/intent issue like you say.

 

[JoshLoring]

You've got me confused now. I'm not sure if I understand what the box that says "use embedded ICC profile" does. Is it referring to the adobe1998, us web coated swop, sRGB, etc. settings or to media profiles? The way I thought it worked, which may certainly be wrong, is that because you're using the embedded ICC profile then the rest of the settings you have screen-shot will be ignored.

-Your settings will not be ignored.. Only translated correctly. If you input an adobe 1998rgb or cmyk and target sign and display- your defeating your input profile. You must input and adobe 1998rgb and output the same to keep the same profile.

Also, I see you're using Perceptual for both vector and raster. I've always seen it recommended to use Relative Colorimetric for vector. I'm curious why you have it set that way.

-Perceptual is better for both when inputting and outputting the correct profiles.

I'm not sure why you say Sign & Display and PrePress have nothing to do with Adobe files. They're just different ICC profiles which affect the color space from what I understand. Sign & Display has a larger gamut.

-You are answering your own question. They ARE different ICC profiles. Why would you design in one ICC and output in a different ICC? If you design in adobe1998 or CMYK.. Why would you output in Sign and display? You have completely changed the color gamut that you designed in.. If you want "what you see is what you get" then you need to input and output the same color profile.. PLUS the right ink media profile.

 

[SignStudent]

With some help from Custom_Grafx through email and some advice others have given in this thread I've finally got the desired result. Here's what I did for anyone who may want to know:

Versaworks settings:
Oracal 3651g Media Profile
AdobeRGB1998 ICC Profile
Perceptual Rendering Intent
Unchecked Preserve Primary Colors
Checked use Embedded ICC Profile

File setup (used photoshop):
Created gradient in RGB
Changed color mode to LAB
Added ~2% monochromatic gaussian noise
Saved as .tif

I can't say I'm positive it's necessary to use LAB; I think the main fix that smoothed out the gradient was adding the noise. You can't hardly see the noise after it's printed, but the gradient is much better.

 

[Custom_Grafx]

Great news - good to hear it worked out in the end!